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Ask GMBN Tech: Should I Get An Oval Chainring?

Ask GMBN Tech: Should I Get An Oval Chainring?


(swooshing) – Hi, and welcome back
to another Ask GMBN Tech. This is the weekly Q&A show. You send your questions in, and hopefully we get to answer them. Questions you can fire into the email address on the screen there. Use that hashtag #ASKGMBNTECH,
and also you can add them in the comments below this very video. So first up is a tire clearance-related question from Jack Bearnes. Ask GMBN Tech, what would you
say is the minimum clearance that I should allow for
on either side of the tire on the fork or the rear of the bike? I’d probably say minimum you wanna have about five millimeters all the way around. Of course, the more clearance
you can have, the better. Because of the nature of mountain biking, you could be riding in mud,
which is gonna clog up. You could get stones and trail debris stuck in your tire tread, which is gonna foul on the frame, can scratch it, all that sort of stuff. But something you also
need to factor in is how stiff your wheels are
and how stiff the frame is. Now, even though wheels do feel stiff, they can still flex quite
a lot under hard loads. So if you’re a heavy rider, or you’re heavy on the bike
in the way that you ride, maybe you like to stuff into those turns, you’re gonna be quite
surprised by the amount of flex a that rear wheel can have,
even if it feels very stiff. And under a lot of flex, it can lead your tire to
buzzing on your frame, which of course is A, gonna slow you down, B, is gonna wear out the
paint work on your frame. Now the same thing can apply to a bike that’s got more flex than one that hasn’t. So, just check those sort of things. If there’s any telltale signs
of any tire rub on your bike, and if that’s the case, then you definitely wanna go
for a slightly smaller tire. But rule of thumb, I
reckon, five mil is okay. I wouldn’t wanna have it
any closer than that myself. Okay, good old oval chainring
pros and cons one here. So, Emil Jensen wants to know, I’m riding a 36 tooth regular chainring, but I have been told that
an oval chainring is good. Can you please help me with pros and cons? Okay, so I actually haven’t ridden any of the new breed of oval chainrings, or certainly not spent enough time on them to really give you the
best bit of feedback. So, that’s something I need to change soon and I can feel a video coming on. But just for the average sort of pros and cons of what you can
expect from an oval chainring. So first up, they kinda
maximize on your power output. So you could argue that they give a better efficiency for your pedal stroke. Now, that is assuming that your pedal stroke
isn’t a perfect stroke. I mean, there’s not many people out there that will have a perfect pedal stroke. So, arguably, most people
could benefit from this. Now you could say that they
also will increase traction by sort of smoothing out
the way that you pedal. So if you’ve got an
erratic way of pedaling, you might find that you stab
at those pedals somewhat, in which case the torque of that is gonna help
the tire break loose. Now, due to the way an
oval chainring works, you can maximize on the traction on offer by smoothing out that sort of way that you apply the
power to the back wheel. Again, so if you’re very good at spinning a smooth round circle, it’s not actually round, but if you’re good at doing that, then you might not notice the benefits. But equally, it’s gonna be very beneficial if you’re not so good at that. I’ve heard that they’re very good for people with flat pedals
because it’s a lot harder to have an equal sort of pedaling
base when you’re pedaling. And some of the cons, okay, so I’ve written myself a bit of a list here to remind myself. So, the first up is probably a bit of a negligible difference. If they were that good, surely
everyone would be using them. That’s just my speculation
because I don’t use them. I’ve never felt the need to use them, but equally, I definitely
want to try them. So I think I’m on a similar. I’m kind of on the fence
with you here probably. Another con is the fact
that, with oval chainrings, you’re gonna be a bit
limited in chain guides. Now, of course, people like Absolute Black make
narrow-wide oval chainrings So, that does get around a lot of the necessity for having a chain guide. But as you might have noticed,
a lot of cross-country, a lot of EXIO, a lot of Endura riders are still running an upper chain guide just as an extra form of protection, just to stop that chain hopping off. And that does become a little bit harder with an oval chainring. Now there are a few
specific ones out there, like Absolute Black, do make one. That’s one on the screen right there. But you’re very limited
in the market for those. And now the final one, is I’ve heard from some of
you guys actually commenting that you think that oval
chainrings actually affect and can wear out the clutch
mechanism on the derailleur. Now it kind of does make sense if you think what the chainring is doing. The chain is actually sort
of stretching slightly as it is going along, so you’re actually actuating that clutch. Now I wasn’t sure about this, so I actually asked
someone at Schram just, have you had this on your radar at all? And they said, we don’t
have anything on our radar about clutches creaking or
wearing with this sort of use. In theory, the dampening mechanism will be activated slightly more cycles
when using an oval chainring, but this hasn’t affected anything to date. Next up is that good
old fork length question that always comes up. A little bit different and
bit more specific though. So, from Reynald Pader, he says, hey Doddy, is axle-to-crown more important when picking a fork than the
suspension travel itself? I ask this because when
I’m trying to pick a fork for my bike without drastically
changing the geometry, it came with an 80 millimeter Suntour XCT with a 475 fork length. I assume this is axle-to-crown. Yeah, generally the length that’s quoted when measuring forks is the
axle-to-crown measurement, so yeah, you’re right there. I found that the RockShox 30 Gold with 100 millimeters travel
has a 488 axle-to-crown length. Will that negatively impact the bike, or should I go with the 80
mill RockShox with a 468? Which of course is slightly shorter than the 475 that you’ve
actually quoted there. So yeah, I think actually
most of the time, fork travel sort of
correlates to axle-to-crown, but you do get anomalies in there. And I’d say axle-to-crown
is quite important, especially on bikes with
slightly less travel, because it’s gonna be more affected by altering that travel. Now roughly, for every
10 millimeters traveled, there’s about half a degree in a head angle difference in that, so it is affected by how long
the wheel base of the bike is and a few other features, but generally, you’re
talking about a half degree. And in your case here, talking about the 488 over the 475, that’s quite a lot. You know, you’re talking
nearly a full degree there, so you have to decide if you wanna actually have that effect on the bike. Personally, I don’t think
a degree is too much to be worried about, but if you’ve got quite a steep head angle it’s very noticeable. And as well as actually adjusting the head angle of the bike, it might be steeper or shallower, depending if it’s a
shorter or longer option, it also raises and
lowers the bottom bracket and steepens or shallows
the seat angle as well. Now, that might sound a
bit negligible to you, but a bottom bracket height
can be noticed quite a lot, even if it is a few millimeters because it really does affect
your position on the bike, how far you feel like you sit into it, and you’re above the sort
of the fulcrum of your bike. And again, with the seat angle, under climbing when you’re seated, you’ll notice it if it slackens it, because you’ll feel the need to sit further forward on the saddle. And quite often you might want to run your saddle further forward to slightly nose-down to compensate if you are slackening that head angle. I don’t think it’s that much of a problem in your particular bike. So you said 80 mil RockShox with a 468, so it’s gonna steepen it very slightly. But the 30 Gold or the 100 mil has 488. It’s not gonna be too
bad if you also factor in is the 30% sag that you
typically set a bike up with. Obviously, if it’s got more travel, it’s gonna have slightly
more sag in relation, and you’re actually gonna bring those numbers back closer
again, so it all depends. If you can put up with it in climbing where you’re naturally gonna be a slightly slacker seat angle, I think you’ll probably be
all right with a 100 mil fork. Oh, this is a good one from Dan D, a chain line friction question. Loving the tech channel, Doddy. I wanna ask a tech question
about 1x drivetrains. I’ve heard that the 1x
chainring sits so close to the frame that when you’re in your smallest sprocket out back, it throws the chain line off
and causes extra friction. In turn, causing a loss in power. What are your thoughts? Well, firstly, it doesn’t
sit that close to the frame. It’s sat basically to give it the best chain line through all the gears. So it sits about halfway
through the cassette, so it’s not too extreme on either side. Now as long as you’ve got
your chain line correct, actually I don’t think there
is that much friction in there. However, there is always
gonna be more friction on the smaller sprockets
than on the high friction, regardless of the derailleur
here for a second. If you think about the chain just wrapping around the sprocket, when it wraps around the biggest sprocket, there’s not as much wrap, so there’s less friction in the chain. When it’s wrapped around
a smaller sprocket and it’s almost all the way around it, the chain has to move a lot more. So, each chain link is doing more, so there is naturally gonna
be slightly more friction. But in honesty, I’d actually
need to put it on a machine to feel the difference,
because I don’t think a rider can feel the difference between that and running it halfway
up the transmission, regardless of the actual
gear that you’re in. I still think it’s that
possible in a mountain bike when there’s so many
other factors in there like the tire pressure you run, the suspension you’re running, how much grease you may or
may not have in your bearings, the surface you’re riding on. Like if you’re riding on grass, obviously, it’s a lot of friction, quite tiring compared to riding on Tarmac. I’d actually really like to try some sort of friction-based testing and spend a couple of days just trying a whole number of different situations I wanna try and find out for real. But I don’t think, in this case, that you can actually
know where you stand. If it was, you wouldn’t
see so many companies dedicating themselves to 1x transmission, and especially with that new
Shimano XTR transmission. We’ve got a video dropping,
a bit of a geek edition, looking at all the facts
and figures to doing that, and it’s pretty impressive stuff. And you know what Shimano are like, I really can’t believe they’d get involved with a little 10 tooth if they
didn’t think it was worth it and it had additional friction. So, shifting issues from New
Zealand, or NZ, Mountain Bike. GMBN Tech, I’ve got a Trek Roscoe 8 with a Sram NX one by 11, and in
the middle range of gears, it won’t always shift, and when it does shift, it skips gears. At the lower and upper range
of gears, it shifts fine. How can I fix it? All right, so first, you just need to identify what the problems are, and with gear shifting,
if you’ve got issues, firstly do a visual inspection. Actually check those sprockets. Check your chain. Make sure there’s no sort of stiff links or any damage with a link that’s maybe split and it could break. Then you wanna look at the
alignment of your derailleur. So, obviously, you wanna
make sure it works smoothly, the cable is working smoothly
inside the outer housing. See, if there’s any sort
of unwanted friction or any gunk inside there, it’s gonna cause the cable to stick and it’s
never gonna shift correctly. But in theory, if you have
your limit screw set correctly, either lower limit screw
for the bigger sprocket and the higher limit screw
for the smaller sprocket, and the derailleur completely
correlates to those, then, in theory, the
only thing you need to do is to let out your cable tension with a barrel adjuster to get perfect shifting. If yours is suffering, it’s
gonna be out of alignment, or it’s gonna be suffering
from stickiness somewhere. So, you just need to factor all those in. I’m just gonna throw you
quickly to some clips from a perfecting your shifting video. The link to that is gonna be in the description below this video, and that will answer all
of those individual things. So, I promise you, if you
run through all of those, you will find your
issue, even if you think that it’s working well at
either end at the moment. Good luck with that. Whistler Bike has got some
10 to seven speed problems. Got a question about setting
up a 10 speed to seven speed. I have an Atomlab DHR Rear Hub,
and it only fits seven cogs. So I took a Shimano Ultegra 6700 Road Cassette and removed three cogs. My question is shifter set up. I don’t like having three dead shifts. Within there, obviously, ’cause it’s designed for 10 speed rather than seven. Can I modify my saint shifter
to make it seven speed, or have I seen a block that fits on the cable to limit
the shift cable movement? I don’t think so. I’ve not seen it. You’re saying that it sounds like something that should exist. The only thing I’ve seen
for shifter modification is from E13 to modify your 11 speed shifter to take 12 speed shifting. That is by including a proper ratchet. You actually take apart your shift and put that inside in
place of the 11 speed one to give yourself the extra click. I’ve not heard of something
to convert a 10 speed, or any other shifter,
backwards down to a seven. The new XTR has it from 12 to 11, but it’s only compatible with 12 speed just for taking off the extra there. No, I don’t think so, but I’d love to know if there is something
out there that does exist because if it does, we’ll
look at doing a video on how to hack a drivetrain like that. In the meantime, I’ll try and find out, but I don’t think so. I think you’re gonna have to put up with those extra clicks, unfortunately. Okay, so next one is bike
fit from Andy Ginther. Doddy, I’m impressed and amazed with how thorough and articulate you are. It’s just research, mate, and in fact, I’m a bit of a bike geek. I love this stuff. Excellent work, man. I’m currently riding
an 09 Nomad size Medium and hoping to upgrade soon. I’ve struggled finding
a stable body position, especially downhill, due to small reach. Yep, it’s always a big problem, especially for taller riders. I have my eye on a new Nomad size Large. I’m five-foot 10, and I like a short stem. Any thoughts on bike size, or ways to find my triangle ratio? I love the fact that you say that ’cause I do completely believe in that basically is the argument for
getting the ultimate bike fit. I had to look online at the 09 one versus the current one,
so the one in the office we have for bike build is a size Large. So the reach on the size Large now is 460 and it’s got a 690 top due. And on your 09 one, it’s 405 and 609, so it’s absolutely tiny by comparison. So no wonder you’re struggling. So at 5’10, I mean Santa Cruz recommend a size Large
anyway for your fit, so I think that’s a no-brainer because it is a nice roomy bike. You’re about to put a
30, 40 mil stem on there. You’re gonna get that nice roomy cockpit, all the control that you
want, aggressive geometry. I mean, you know already
if you’re looking at a Nomad, know what you’re
dealing with there. I always tell people to size
up on bikes if they can, or at least try and pick the right size as opposed to picking a smaller size in the theory that you’re
gonna get to throw it around because all that’s gonna
happen is yeah, all right, if you’re really into jumping, a small bike can be very beneficial, but if you wanted to go fast off-road, a nice long bike that you
sit into the frame properly is always gonna be better
than a short wheel base bike that doesn’t fit you or
your weight is all up top, and a bit of weeble-wobble. It’s almost like a big pendulum that wants to take you off the bike, and accordingly, you’re
leaning too far back and too far forwards the entire
time to get that balance. Definitely go for the Large. I would still try and get a
demo on it if I was you though, but good luck and I hope you enjoy it. So that’s another Q&A session in the bag. Hopefully, it’s answered some questions. If you’ve got any, add
’em in the comments below, or fire ’em into the email address at the beginning of the show. For a couple more tech-related videos, click down the bottom
there for the bike fit one. So this is answering a lot
of problems a lot of you ask all the time about
having hand pain when riding, not being able to manual,
all that sort of stuff, so click down there and
hopefully it gives you a better idea of how to set your bike up and to understand the effects of what those things do to other
things on the bike. And if you wanna find out a
bit about what a chain does to actually affect suspension, click up here where Neil basically set up an idle wheel system on his bike so the chain passes over it, to see how the bike felt
with isolated suspension. Pretty tech, pretty geeky. We’ve all known that
people have been using this sort of stuff for a while, but Neil’s put it to the test. It’s quite cool. So, as always, click on the round globe to subscribe to the channel, ’cause we’ve got new content
for you every single week here. At GMBN Tech, we love having you around, and if you like asking
questions about tech, give us a thumbs up.

100 comments on “Ask GMBN Tech: Should I Get An Oval Chainring?

  1. YES Absolute Black 32 tooth on my 2018 Trance 3. I ride a lot of dusty, loose over hard and I climb a ton, with the full squish, it kicks out and spins the rear wheel a ton without an oval chainring, especially with clipless pedals. 100% worth the cost, and extremely noticeable. I've got well over 200 miles on the oval ring and wouldn't change back.

  2. Riding flats the oval is most noticeable on loose climbs … does it wear the clutch? I think so having had to replace 2 but they are £10 or so (Shimano anyway)

  3. for the fork question, go for the longest travel you can afford (i suggest dont go over 150mm) (take this with a grain of salt…)

    my old specialized pitch comp 650b size small (2015) had a 80mm suntour on it. then one day i was browsing through CRC and saw a 2016 pike with 160mm travel (rct3) for 500€ and i bought it. after installing it, i noticed how slack the bike was (70.5 deg ha to 64 deg ha) and suprisingly it made the bike feel so good….. it suited my riding well..

  4. I have a 2018 Giant Stance 2 with 120mm travel sr suntour suspension, I’m a heavier rider at 220 lbs and i feel that I don’t quite have enough travel for bigger hits what would be the pros and cons of buying forks and a shock with maybe 140mm, or even 150mm travel, and would I benefit more from maybe a set of fox or rockshox 120mm suspension? Love the show by the way … very helpful!

  5. #askgmbntech I have just bought a pair of tubeless compatible tyres (26×2.1 inches). My wheels are not tubeless compatible but if I was to go to tubeless would it work or would the tyre just deflate?

  6. Actually i think a oval chainring shouldnt affect the derailleur as the chain length doesnt grow as you might think. Matt Jones uses an oval chain ring on his dirt jump bike, ie a Hardtail, with no chain tensioner.

  7. Back in the 90’s when I was a teenager I bought a 2nd mountain bike and it had an oval chan ring I think it was even a 3x oval tech system. It was great for popping wheelies

  8. To stop a shifter shifting to the last 3 clicks cut the end off a cable crimp remove cable from last section of casing slide crimp on refit cable select the last gear you want crimp at shift side cable stop not rear else you will have achieved nothing 😉

  9. This video has spike me to go back using my ovals. I used them for about 3 months last year to test. It took me about 2weeks to completely feel normal to use them. As my fitness has been changing all the time, I couldnt tell if i had improved efficiency using it. All I know is that I could use a lower gear more comfortably when spinning at higher rate. I changed back to normal ones it took me a few days to get used to it completely.

  10. With my long legs I always tend to fall in between a size M or L. Earlier this year I demoed a rockymountain instinct in both M and L, in that case I felt much better on the size L bike. Now a few months later from that I bought a scott genius and was struck with the same thing, do I go M or L? Advised by the LBS I went with a M and the bike feels GREAT, all I had to do was get a longer dropper post (went with the 160mm highline) to get my saddle at the correct 782mm height for me. I haven't had a chance to test a size L genius tho so can't really comment on that :/
    Doing some later "research" later for fun I learned the avg Leg to Body Ratio is about 45% while apparently mine is around 49.5% based on the measurements I got at said LBS.

    TLDR: For some people finding the right bike size can be annoying and change from brand to brand it seems. Once again shows how important it is to demo before you buy, ESPECIALLY if it's for your first (few) bikes. After a while you'll start learning what kind of geometry you want so sizing should become a lot easier in time.

  11. If you run 2x or 3x, the front chainring, when in gear with the most teeth it’s a harder gear, but with the cassette at the back, the more teeth, the easier the gear. Please can you explain. This is driving me insane. Thanks

  12. #askgmbntech Hey Doddy, what do you think about bike fit for different legs length to height ratio across human population?
    I'm representing Ural low-butt human breed who've got very specific anatomy of my ancestors who have been riding horses 90% of their time.
    We have long spine and arms, but short legs.
    Im 173cm and Specialized frame charts, for example, recommend me M size. Which frame size should I use from your perspective?
    Here's short article about it http://siberiantimes.com/other/others/features/bottoms-up-not-in-the-urals-and-siberia/.

  13. #askgmbmtech

    I have a bike that is old. What part would make the most impact on how better/newer it feels?

  14. Open question to anyone who owns or has knowledge on canyon strive. What bottle cage do you use coz I can’t find one that fits on my 2017 strive al 6.0

  15. Running a 1×9 32t Snaggletooth oval by Blackspire on my 99 Giant Team DH. Noticeably better than 32t RF NW round it replaced. It smoothed my stroke out on climbs, but made it choppier at times, like resuming pedalling after coasting. Overall, my knees love it!!!

  16. I have been riding one for two months now and I can honestly say I love it. I will be adding one to my fat bike and my hard tail.

  17. How often would you say I should change out my brake pads, given I put in about two quality rides a week

  18. #ask gmbn tech i have a specialized pitch comp size small that came with a 80mm travel firk i was wondering if i can upgrade to 120mm travel or if i should only go to 100mm travel the otger sizes of my bike came with 100mm travel

  19. #askgmbntech hi doddy love your show what do you think is the best way to loose weight faster? Pedaling on low gear or high gear? Cheers from the philippines.

  20. You don't have to keep buying all the crap you see being advertised, buy a bike get out and enjoy it , don't let products cloud your vision they are just after ur cash, if you break a wheel then you need another one cos your bikes broke , and you can't ride it , seat droppers , oval chain rings , etcetc they just want you to part with the loot ,

  21. Doddy, thanks for addressing my concerns about running an oval with the clutch. I'll now upgrade my new Stumpjumper without worry. Cheers!

  22. @9:00 Friction Facts. Has done a lot of the testing you may be interested in. The site that did the work is gone, but I bought a copy. I now make my own chain lube a sa result.
    You can read upon it in this article and if interested get back to me.
    https://www.bikeradar.com/us/road/news/article/friction-facts-publishes-ultrafast-chain-lube-formula-36424/
    Here is a small sample of the data set.
    http://xcterra.ru/FriFac/10_ways_to_increase_drivetrain_efficiency_4.pdf

  23. For the 10 to 7 shift, some manufactures run seven speeds shifters on kids bikes eg 3 x 7 speed, I had just changed my sons bike from a grip shift to a ratchet shift on his bike.

  24. #AskGMBNTech Hey, Doddy, I'm a Mechanical Engineer from Bengaluru, India. I have a Marlin 6 which I bought last October. I use it for commuting and XC. I am experiencing a small problem with my front sprockets lately. I use the following gear ratios, largest 4 cassettes with the 24 teeth, 3,4,5,6 with the 34 teeth, and smallest 3(6th, 7th and 8th) cassettes with the 42 teeth. I don't know the exact terms to use to explain my problem so i will use an example. I changed from the 42 teeth chain ring to the 34 teeth, so from my knowledge, the chain should shift in about half a revolution of the crank. But, what happens(sometimes(once every 100 gear shifts or so)) is, as I'm pedaling, the upper part of the chain slowly shifts to the 34 teeth chain ring but even after half a revolution, some part of the chain is on the bottom part of the 42 teeth chain ring. As I continue pedaling, the chain is pulled back and gets stuck between the chain ring and the chain stay. Meaning, the chain, from the bottom of the chain ring is not traveling towards the rear derailleur but moving with the chain ring till 3/4 crank rotation where it gets stuck between the chain ring and the chain stay. This has resulted in one of the first scratches…… What do I do???

  25. I've used Absolute Black and OneUp oval rings with the MRP 1x guide for a couple years with no issues. A small bit of extra traction on loose punchy climbs is the only thing I notice.

  26. One thing that isn't mentioned as much when it comes to oval chainrings on full suspension bikes is that when the ring is at its narrowest, the suspension's anti-squat values are increased during that stroke phase so the bike actually becomes more efficient by preventing pedal bob

  27. Hey GMBN! Love the show, keep at it, i was wondering whats the best bike for every type of riding, DH, Enduro, the lot! doesn't matter if it's hard tail or soft tail price around 2500 pounds for a 14 yo, thanks 🙂

  28. oval is best most would think that it stretches your chain but in fact when the high point in the chain ring is in action the low points actually inversely allows slack its some serious engineering that makes it so good in fact Matt Jones runs one on his single speed slope style bike with no chain tensioner and it works flawlessly

  29. Hello, just got my new bike a week ago and down about 10 miles on it, but didn't bed my breaks in correctly, the breaking doesn't seem powerful enough, do I need to do anything?

  30. #Askgmbntech I have a press fitted BB on my bike that starts creaking yet again. Are these glue-in adaptors any good to convert to a screw-in BB and mount holowtech II bearings and crank? I'd have most of the parts around, so I'd just need to buy an adaptor.

  31. Is it only me who is a little annoyed by the piano music in the background? Why is it there all the time? Once you notice it there is no way back!

  32. #ASKGMBNTECH hi doddy I have the idea to convert to tubeless recently, but my Friend advice me not to . And I have this idea in mind that can I still use tube , but fill the tube with sealant (maybe muc-off no puncture ) and air. Making it like tubeless, but still using tube. Is this possible ? And where can I find handlebar that can be extendable ?

  33. Soz that was rapid rise for normal mechshifter set shift to 3rd set rear mech  to 1st then crimp as last stated 😃

  34. I had one after dislocating my knee cap. At first it was great, took a lot of pressure off the knee (32T version). However, this year (after my knee was good) I noticed that my stroke was not smooth and seemed like I was wasting power. I had my buddy ride behind me notice it before I even said anything about it, so I have gone back to a regular ring.

  35. this is stupid who the fuck calls it a chain ring I've always called it a sprocket and thats what every one I've bought is called. never seen a box with the word chain ring on it

  36. Doddy, there is a limiter for a 10 speed derailleur to run 7 speed. It basically clamps on the cable to limit the derailleur from moving to the lower gears. I have one that came on my new Demo 8 DH bike. I'll see if I can find the resource.

  37. Hi Doddy, I have a Orange Crush s 2016 in a size XL(140mm of travel) I was wondering if adding a angle adjust headset (-2 degrees) to change the head angle to 64 from 66 degrees would mess up the handling of the bike? Cheers.

  38. Matt Jones uses an oval chain ring on his single speed dirt jump bike, with no derailleur, so it has no reason to wear a derailleur.

  39. #askgmbntech
    I ride a 2018 Kona Fire Mountain and im looking to upgrade the front fork which is a Suntour XCR 32 LO-R coil fork with 100mm of travel, i want a fork with atleast 140mm of travel but dont want to break the bank, got any suggestions?

  40. What? 03:31…An erratic pedal stroke can make the tyre break loose from the rim…WHAT???? Go get a early 90's MB. BIOPACE.

  41. Recently switched from a normal 30T chainring to a 30T Oval – big improvement in climbing and won't be changing back 🙂

  42. HI Doddy i have a dilemma, i have a fox 34 with a 195mm steerer tube, and have bought a new set of Fox forks with more travel with a steerer tube of 170mm, my headtube is 130mm and have just ordered a dmr defy stem which has a 31mm stack! my hope one im replacing is 45mm stack, the bike has a 10mm spacer below the stem which i could remove if need be .which leaves me 1mm short, do i go this route or should i try a bbb steerer tube extender, i plan on using the bike for bike parks and enduro, thanks again .#ASKGMBN #ASKGMBNTECH

  43. #gmbntech What tools you think are ”a must have” for every mtb rider to keep your bike in shape in everyday use. I don’t have room for all the bells and whistles in my tiny flat.

  44. Is it ok if I change my fork travel from 100 to 120 on my stumpjumper hardtail? Wil this do damage or not?

  45. Doddy, I was wondering if you could explain the size triangle ratio. I am also looking into a new bike and sizes. I rented an XL which felt too big but got comfortable while I rode it. And I've also rented a L which felt comfortable immediately but still didn't feel right. I am 6'-6'1" and currently ride a M frame hardtail. (My second bike and it was a cheap used bike better than my first bike) [email protected] if you wouldn't mind emailing me. Or letting me know if you talk about it more. Thanks. -Nate

  46. #askgmbntech
    Hi Doddy,
    Love the show! Keep them coming!
    I have a set of 2004 Hope M4 Mono brakes that have been sat in the garage for a while now and I’ve just bought a new bike which has non-series Shimano brakes. So the question is, are 2018 non-series Shimano brakes better than 14 year old Hope brakes? Is it worth me swapping them out?
    Cheers!

  47. #askgmbntech hey doddy,can I fit a superstar components 2 degrees angleset headset in my Cube stereo 150 29?
    What model shoud I choose es EC44,ZS56…?
    If I can't is there another one that fits in it?
    Thanks

  48. Can i have some advice. I can't decide between the YT jeffsy al or the Canyon Strive al 5.0 I'll mainly be riding trails with various dirt jumps every now and again #askgmbn

  49. Hey Doddy ….. a few shows back, you recommended checking out Cane Creek for an angled headset.
    After going through their filters, there was no headset to fit my 2015 GIANT TRANCE …..
    Looking for a quality angled headset … what do recommend?
    Thanks for sharing you mountain biking expertise with us

  50. I was running an oval on my hardtail for about two years. I then got a new FS bike with a round 32t and couldn't take it, ordered an oval within the first week of having the new ride. I had knee pains prior to ever switching to oval, now I never have knee pain.

  51. #askgmbntech can I convert to tubeless using a tubeless ready tyre which has a small thorn hole? if so, should I do anything different?

  52. There is so much bias in biking it's astounding. If the oval chaining or lefty fork or tubeless systems were first we'd be just as sceptical of the current standards if they had come along second. BUT… Better systems are not so obvious and take time to develop. I welcome most of these new developments.

  53. #askgmbntech Hi, love your tech show… Recently, I discovered a scratch on the side of the downtube of my carbon frame. I guess it is about half a millimeter deep, about 10 cm long, and it was most probably caused by some flying rock or branch. The color of the bottom is white, unlike the black of the cover paint.
    What would you recomend I should do about it? (Bike Canyon Exceed CFSL 5.0)

  54. @askgmbn hi Doddy loving the show, I'm 5"6 and am riding a brand x ht01 hard tale with 27.5 wheels I think the top tube is 570 running a 45 nukeproof stem, 120mm rockshox reckon forks,and having issue getting the front end up, watched countless number of videos of how to bunny hop and manual, I used to be able to years ago(10-15) on a Claud Buttler Cape Wrath from I think 2000-2003, I was jumping about a foot to foot and a half, and as I said having issues, any help would be grateful

  55. I just mounted an oval chainring and climbed 3-4 times the same 20% uphill i used to climb everiday for years… I cand say that now my front wheel stay on the ground cause my pedal stroke is very round! That's great!

  56. I tried an Absolute oval in thick mud and the chain was coming off at every crank turn. Not even worthy of the recycling bin.

  57. I just wanna hear peoples opinion because i wanted some cheap dh brakes… i found 2 i liked shimano Zee and magura mt5. their abour same price wich ones better?

  58. The rear mech has to die quicker,its constantly on the move,my g2 supports only round,round wheels,round hubs,round bearings,tyres,,cassette and the pedal rotation,all round,ill go round,it seems more intough with the physics of motion,however had xt bio pace around 1990,a brilliant 3 ring crank for xc,climbs and flat miles,round feels slightly more torqey on downhill,keeps traction good

  59. I use oval rings on all my bikes and the benefits are most noticeable on a singlespeed as there are no hiding places for the effects better climbing on previously gut busting climbs higher average speed and better traction, there's no more chain growth with oval than with round rings, believe or not round rings aren't perfectly round. Clutches need periodic tightening on whatever bike you use them on and having oval rings is a red herring with regards to determining the cause, it's quite simply wear and tear on the rubber bung which happens through normal riding as the arm does still move just not as much. Reason being is that with oval rings no matter which part of the pedal stoke your In there is always the same amount of teeth engaged with the chain. I use mine with no chain tensioner and there is no more chain growth causing tight or loose parts of the revolution than a round ring.

  60. #AskGMBNTech what is the possible reason why rotors bend , im using shimano rt66 for a week when i hear noises from my rotors , it never bump on to something and my calipers are perfectly aligned, thanks

  61. I did buy an oval chainring from Absoluteblack, and I didn't feel so much difference, therefore my time are a little bit better on climbs, comparing to 2018, the same as in 2017, so I think the oval chainring is better, at least for me!!!!

  62. Thank you. You guys are the winner! I've got an old 1987 mtb with a Biopace chainring. The crank is aligned with the widest part of the gear. A series of videos I watched say that I should move the crank position. The well meaning Youtuber however holds chain rings and talks and talks and explains. He's even got some graphs. I can't follow him. There are five screw holes in my Shimano Biopace chainring, so it's obvious that if my old factory setting is not ideal, then the better option is either to rotate my rings 72 degrees clockwise or 72 degrees anti-clockwise. Finding out which has been nearly impossible. (Weird huh?) Googling this different ways I finally got a link with a thumbnail clearly showing that the wide part should be 72 degrees in front of my crank arm. That's to this video. So thanks. I'll give try that.
    Do I like my Biopace? I've been pedaling them for 32 years (but not regularly.) I'm used to them, but I don't know. I've ridden a lot of bikes without them and they're okay too.
    I think your point about they may be best for flat pedals, no clips or clipless is excellent. Makes a lot of sense. I clearly remember when I first installed clips and straps and started lifting up with my off leg. The term 'crank' lost some of its meaning as I was now more machine (spinning?) keeping my cadence going. So higher cadence and clipping in probably does eliminate most benefits from an oval chainring.
    Going up a steep climb is when I most notice them. If you re-visit this topic I think that would be a good place to start.
    Would I buy a new bike with Biopace or some other oval chainrings? Maybe, but I probably would select other aspects first, like a really low climbing gear and a good high gear ( I do a lot of my riding on the road, so a 1x chainring is an immediate no). Would I spend say $100 on non-round chain rings as an upgrade to a new bike? I'd want to see a lot more clear information first. *The big unanswered question is: Shimano clearly did some research, thinking and engineering when they invented the Biopace, So why did they get the position wrong? Or did they? *

  63. I have been on an oval ring for 2 years. There is a learning curve. I would say a good 2 weeks for regular riders. I did some back to back testing on a round and oval. Same say, Same segment. I changed the ring at the trail head. I was a touch faster with the oval with the same HR day one and close to 15 seconds after a few weeks on it. My biggest improvement is on switchbacks where elevation pitches or if there is a quick change and then return to same grade in elevation. Probably not for every one but works well for me.

  64. Used to run these back in the late 90s when Shimano was specing them on triples…. I'm building up a used 2017 Devinci Troy and with the 1x setup…I'm considering using one again after 20+yrs

  65. On oval chainrings: Been watching them since the 80s.
    1. Can someone ask a physicist about torque, power and the actual lines the forces take. I am tired of the subjective “they feel good”. I am also tired of the line that the short axis has the diameter of a 32” while the long is more like a 34”. It don’t matter! The RPM is the same, the rear cassette has no idea how it’s being driven.
    2. If they are better, everyone would have them, yes?
    3. Can someone do the simple experiment of mounting one with the oval 90 degrees from the way it should be mounted? Presumably the bike would ride very, very poorly. Same rider, same bike, velodrome conditions, oval mounted correctly and then incorrectly.
    4. If all this could be done without mentioning a manufacturer’s name, that would be great too.

  66. I got fsa 34t chainring and I want to change it to diffrent colour but I don't know what the bcd is can anyone help please the bike is a voodoo hoodoo 2018 model

  67. A long time ago I used a biopace chainring. It worked pretty well for climbing. I didn't notice anything on flat. Those were a bit different from the ones they have now

  68. I just tried an oval chainring and I love it. It feels more natural, your pedal strokes are smoother, and ironically it feels more round. I noticed it most when standing up, it's easier to apply a constant supply of power without feeling punchy and uneven. I just climbed a local hill standing up in top gear which I've never done before. I'm on flat pedals fyi

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