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Should You Ride Shorter Cranks On Your Bike? | GCN Tech Clinic

Should You Ride Shorter Cranks On Your Bike? | GCN Tech Clinic


(whooshing noise) – Welcome to this weeks’ Tech Clinic where we aim to answer your tech questions and queries about your
bikes and equipment. Now, if you’re wondering where John is, well, he’s at the world
championships in Harrogate on the hunt for hot tech, though I hear it’s currently
raining there at the moment. Now if you’d like to
submit your questions, you can do easily in the
comments section down below, just use the hashtag ASKGCNTECH. And if you haven’t already, please subscribe to the channel, and also click the bell icon, that way you’ll get a notification when we upload our next Tech Clinic, which might even have an
answer to your question. So without further ado let’s get going. The first question is from Oneris Rico, he says that he’s just got a new TT bike, and he got a great deal on it. Good, love TT bikes. But he says that it has
shorter cranks on it than his road bike, and he said that he’s
temporarily had to try some longer cranks on his TT bike, and it had a big negative
impact on his performance, and he says he knows that
there’s a difference in torque between different crank lengths, so if you use longer cranks, they generate more torque. And he’s wondering if he should switch to shorter cranks on
his road bike as well, and will that be a
benefit that he’ll notice. Well, shorter cranks
are really interesting. I’ve experimented with
it myself on TT bikes, changing my crank length. I didn’t put shorter ones on, I put longer ones on, and the idea with short cranks is that they allow you to open your hip angle more when pedaling. Now the torque you produce
from a shorter crank is less, meaning longer cranks have
kind of bigger effective gears. But this shouldn’t really matter too much, you can compensate for that
by just being in a gear lower, so don’t worry too much about that, that’s not a reason not to do it. But by using shorter cranks, you can open your hip angle more. Now, this can really help
with getting the power out in an aerodynamic,
aggressive, TT position. A closed hip angle means that your legs are brought up closer, tighter in to your chest, and this can be less efficient. It can be harder to recruit some of the most powerful
muscle groups in the body, so, like your glutes and your hamstrings, and so with shorter cranks, you’re able to recruit them
in a greater range of motion. Personally, I’d love to try
shorter cranks on a TT bike. I’ve got a TT bike challenge coming up, and I’m actually thinking about trying shorter cranks for
it, something like 165’s. In the past, I’ve used 172.5’s and gone up to 175’s, and I found that that two and
a half millimeter difference, to me, I too noticed a big drop off. I found it really difficult. On the road, if you
ride in a more upright, less aggressive position, as
people often do on road bikes, then the hip angle is likely
to be more open anyway, meaning that you might not
necessarily need shorter cranks. It might not make much of a difference. But, if you like it on your TT bike, it’s worth trying on your road bike. And if you can replicate
your TT bike position to be more like your road
bike position, or vice versa, then you’ll get a greater training effect for your TT bike when you’re
out on your road bike. Give it a go. Our next question is from Richard Clayton, he says, Hi, I’m taking a trip abroad with some decent climbing, and I’m wondering, could I use a Shimano Tiagra 4600 chainset, compact, 5034, with an
Ultegra 8050 groupset, which is 11 speed, which currently has
5236 chainset on there. So he wants an easier gear. The problem you’ve got is that the Shimano Tiagra chainset is 10 speed, Ultegra 8050 is 11 speed. So it may work to some degree, but I wouldn’t recommend it. The spacing between the chainrings is different from 11 speed to 10 speed, and the chain is a slightly different thickness, different gauge. Now, one of the great things
about the Ultegra chains that you have though, on Ultegra 8000 is the bolt
spacing for the chainrings is universal on those cranks. That means that now, you couldn’t do this with older Ultegra, but now it’s all 110 bolt spacing. What that means, is, that you can put compact
chianrings on there, mid-compact, like you have, or even you can go up to 55 chainrings if you really want to. The great thing about that means you could just buy some compact chainrings for your Ultegra chainset and put those on if you wanted, and that way that will work fine. If you want to spend a bit less money, you could get the 11 speed 105 chainrings and they’ll fit on fine. They might just have a
slight difference color, but it’ll still fit fine. And that way you can get a 34 on. Just make sure if you do that, that you lower your front
derailleur slightly, if you change compact rings. Another option if you don’t
want to change your chainrings is to get a different cassette on the back if you haven’t done already. So you could get a 30 or a 32 cassette. If your Ultegra has a long cage rear mech, then it will take up to a 34 cassette. If it’s just a normal one, then it’s officially
rated to a 32 cassette. But, it will take a 32. I know because I’ve done it. You just wind in the B-limit screw. I did that for my Everesting and it works. Have a question from the THEoldgreydude. Now, who says he loves the show, and he has a question
just out of interest. Not many things on bikes are standard, there’s so many different sizes and types of headset, and bottom brackets, and hubs, and all the rest of it, but pedals, the threads on them, seem to be all the same. Was there ever a time when there were several different sizes of pedals? Well, if you are THEoldgreydude, you can’t be that old, because, well, even in the 80’s, there were still
different pedal standards. But it’s a good question. Thankfully, we only really have one pedal standard these days, but imagine if it were like bottom brackets
(makes shivering noise). That would be horrendous, I mean, it’s a good fact actually, the first bikes, people’s left-hand pedals kept on unscrewing, so this is back in like Victorian times, 1800’s, and they had to work out that they needed to put a left-hand thread
on the left-hand pedal to stop it unwinding as
people rode it. Crazy. Anyhow, most pedals have a 9×16 inch by 20 thread per inch threads. Although, pedals for one-piece
cranks back in the day did have a half inch by
20 thread per inch thread, if we’re getting really nerdy and geeky about this. And then older french
bicycles used to have 14×1.25 millimeter threads, but these are pretty rare. Thankfully you don’t see many of those. But there you go, anyhow. You asked so I answered. Next up we have a question from Dapster, who says he loves the show. My question is from the
advent of thru axles, how come rim brake bikes
don’t come with them? Since road bikes use 100
millimeter forks with a thru axle, I’m sure they could do
the same for the rear. 135 millimeter rear thru axle would be brilliant on a rim brake bike. The answer is that they’re heavier, and they’re designed to deal
with heavier loads on the axle. Now, on a road bike with rim brakes, this isn’t required a lot of the time. It might be beneficial to some really powerful
sprinters, perhaps, but disc brakes require them because of the larger asymmetrical
torsional strain that’s developed from having the brake low down next to the axle on one side. And so under braking, it’s creating a twisting force in the bottom of the fork, so you need that greater strength and rigidity of the thru
axle holding it all together. So that’s your answer. Next up we have a question
from Solid Velocity who says, what do you do when the disc
rotor is not rolling straight? He says his road bike loses a lot of speed when the disc is rubbing
against the brake. Yeah, unfortunately this is quite common. Disc rub can be really annoying
when you’re riding along, and you got that (makes rubbing noise). You can use a tool to
bend it back into place, if the disc is warped or bent. But before you do that, check that the caliber
is aligned properly. If the caliber has been knocked, then it might be rubbing on the disc. Now, we have video where it teaches you how to recenter the caliber, so you can make sure that the
disc is right in the middle. Now, if you’ve tried that and you can see that it
is the disc that’s bent, it’s easy to check, you can look and you
can just spin the wheel and see as it moves around, if it’s, like, got a wonky disc, you’ll see it moving. If it is warped, then you can try and bend it back with a tool. But generally the best thing is to do, is, unfortunately to replace them. Because once they get hot again, then can often then bend again, and it’s very hard if a
disc is badly warped or bent to ever get it back perfect. It’s tricky to do. It’s one of the unfortunate
downsides to disc brakes. A question from Rhys Morgan here, who says he’s got a
Canyon Aeroad CF SLX Disc. Good bike, that. And he’s currently running
Shimano Ultegra 6800 Mechanical, so he’s on Canyon’s mechanical frame set. He’s going to upgrade to eTap, which means that he’s
no longer going to need all the little holes for wires and stuff there in his frame, and he’s wondering if
there’s any hacks he can use for grommets or bungs to cover the holes and protect the frame. Are there any hacks or
bodges that you can do? Well, a short-term fix is
a bit of electrical tape. That’ll, you know, worth doing, especially around the head tube, ’cause it will stop water getting in there and potentially affecting
or washing the grease out of the bearings that are in your headset. Other brands may have frame grommets. You say that Canyon doesn’t
offer the frame grommets for that particular issue. Other brands will have frame grommets that will probably fit or that you could slightly
modify to make them fit. I would investigate that. Failing that, I would love
to hear from you guys. If anyone watching has any suggestions of hacks that Rhys can do. I mean, if you really
wanted to go to town, you could go to carbon bike
repair frame specialist, which is carbon bike repair
who we visited before, and then they can completely cover it up the holes with carbon and glue color matched with
the rest of your frame. But that would probably cost more than you’re wanting to spend, I’d imagine. So let us know in the comments if anyone has any suggestions for that. A question now from mm3burnett, who says, I am upgrading my cassette and crank sprockets soon and was wondering, has anyone
ever powder coated them? I’d like my bike to stand out, but I’m unsure how it
would affect shifting. I don’t think a powder coat
would last on most components unless it was some fancy-pants
tungsten carbide coating with really high hardness on it. But, I mean, it would probably come off as the chain runs through it, and end up clogging up the chain somewhat with a bit of residue. And I would also imagine
that a powder coating adds quite a bit of thickness, enough, I would imagine, to interfere with the tolerances of the ramps that are really, actually,
quite precise on the cassette which could well affect your shifting. There are loads of other
things that you can do, though. So Wend Wax is a colored
wax that you can get in various different colors, you put that on your chain
if you really wanted to, or you could get a gold chain, I mean, we all love gold chains, and KMC, they also do different
colored chains as well, so you’d get a colored
chain, perhaps, as well. But unfortunately powder
coating your chainrings, yeah, wouldn’t suggest doing that. Lastly this week we’ve got a
question from Yeahbutnobut, who says, can we all just
agree that front derailleurs are more trouble than they’re worth, and can we move on now, please, I’m a mechanic and they’re
the bane of my life. Uh, no, no we can’t. Well, one by systems do have
some advantages, admittedly. They’re lighter, they’re more simplistic, there’s less to go wrong, and they can be more aerodynamic too, and they can look nice as well. You have fewer gears, you have bigger jumps between those gears, and, well, narrow wide front chainrings are less efficient in terms of friction and drive train efficiency
than two by setups. So, no, I quite like to
have the option of both, and I’d like front derailleurs to stay exactly where they are for the foreseeable future. Anyhow, I hope you found this video interesting and informative, and if you have, then please give it a thumbs up. Don’t forget to submit
your questions down below using the comment section and the hashtag ASKGCNTECH. And if you’d like to get your hands on one of these awesome GCN hoodies, well, you’re in luck, they’re available in the shop. This one’s actually my favorite navy and white classic combo. To watch more videos, you click down here.

100 comments on “Should You Ride Shorter Cranks On Your Bike? | GCN Tech Clinic

  1. We love to help here at GCN Tech, so if you have a question that you'd like us to answer leave it in the comments below using #AskGCNTech

  2. Fill your holes with CT 1 .. you can get it in different colours , its like silicon but not and wont damage . Completely waterproof.

  3. Chainrings on Shimano, despite being the 110 distance, are not universally interchangeable: They have grooves and ridges that won't match those on the ends. You'd need to file a bit. I for one recommend getting a Specialites TA set. As long as the minimum teeth distance of 12 is maintained, you can use any combination!

  4. I agree with Ollie, have never had any issues with a double chainring up front. Have logged 40,000 miles in the past 5 years including 10,000 on gravel, have never once adjusted or dealt with any issue with the front derailleur on any of my bikes.

  5. love my 150mm cranks on the roadbike. My utility/travel bike has 152.5mm cranks that were cut and drilled from 175mm cranks, it had long flat section to allow new hole

  6. For two years now I'm running a 52-34 instead of 52-36 with 11-32 on Ultegra Di2 without any trouble. And it's quite a cheap thing to try.

  7. In regard to the recommendations for the user looking to swap the 10 speed crank on an 11 speed system, I wanted to add additional points that were omitted in the video. 1. Don't put a 10 speed crank on an 11 speed system, since the chainrings are thicker and spaced further apart, the chain has a far higher likelihood of getting stuck between them, which is the main reason not to do it. 2. If you are up-sizing your cassette as recommended in the video, you will also likely need to install a new chain, or additional chain links, as additional links will be needed to take up the additional chain wrap required by the larger cassette. If you don't do this, it can bind the chain and prematurely wear on the rear derailleur when in less favorable big-big chainring/cassette gear combinations.

  8. A really cheap hole plug are foam ear plugs. Squish, insert, let expand, trim to length and paint to match specific frame area where they'll be installed.

  9. #AskGCNTech Hey guys and girls! Love the show, it's like FAQ for cycling tech, but I can't find a tip for a problem at hand. I run a ultegra 6600 group that has some glitches while shifting at the back. The cables are relatively new, the tension adjusted, but the movement seems restricted laterally. While looking down the sprockets in line with the chain, the chain moves up and down the cassete with slightly smaller jumps, enough that it rubs against the previous cog but only in certain gears. Is the hanger bent (had no falls), are the cables in need of lubricating? Please help, I've adjusted the derailleur too many times without success.

  10. Great video, but Oli made one mistake when talking about pedal threads. A left-hand thread on the left pedal will actually cause the pedal to loosen with the forwards pedalling motion. Pedal threads where designed like this when bearings were a little less reliable; so when your pedal seizes up, it'll simply come loose rather than snapping your ankle.

  11. I really wish Road bikes came with thru axle dropouts. These days manufacturers use full carbon dropouts and they are very easily worn out.

  12. 8 years in cycling, I've been using 170mm crank but last month i decided to try 172.5mm crank and i found that my average speed increased a lot, and its easier for me climb.. For me longer crank is better than shorter crank, because I am not a spinner, my cadence is 70-80rpm.. and my bmi is 33.4(obese)

  13. Park Tools should develop a disc rotor press. they could machine various tolerance molds to place a bent rotor in, apply just the right amount of heat, then cooling the metal rapidly to harden it again. like a George Forman grill for brake rotors.

    or am i just high?

  14. #AskGCNTech, i have a 105 5800 group set. Izzit posible to buy di2 8050 upgrade kit and upgrade my current setup, or will i need to a newer version like R7000 or a whole new di2 groupset.

  15. "I'd like front derailleur to stay exactly where they are" except when you're shifting gears in the chainrings or changing your chainrings sizes!

  16. Ollie, I feel bad that you didn't get to go to your home county to look at the World Championship bike tech, but glad that you made us a video. If this keeps up, I'm just going to assume that you're the regular Tech Clinic presenter and Jon is a temp worker.

  17. How do you fix a hydraulic caliper piston that's not retracting symmetrically (at rest one piston sticks out from the cylinder far more than the other), and though the caliper is centred, one piston still rubs.

  18. Shorter crank arms allow for more ballistic pedal movement, in turn (no pun intended) allowing the rider to turn over the pedals faster. You can improve power much more training and experimenting with gear ratios then having a longer crank.

  19. Started on my track bike with 165mm cranks , im about 167 cm so pretty small rider , i tried 170mm cranks on both my road bikes and track bikes and it just feels too long , im thinking of eventually trying a 160 or 155mm crankarm on a small build if i ever get the chance

  20. 4:25 "You couldn't do this with older Ultegra…" Incorrect. Since 6700, Shimano has used universal 110 BCD. All 11 speed cranks have used universal bolt spacing spiders and you can swap chainrings to any of the options available without needing to buy new cranks.

  21. That was a strange request on the last question. I have no problems with my front derailer, it works perfectly fine. Admittedly having di2 makes changing gears easier but even with mechanical gears I have not had any problems.

  22. For the Canyon frame: You can use Sugru. It's moldable glue that you can use to fill the hole and even paint it to match. When / if you want to remove it you can just pick it out and it will come out in one or two pieces. Dry its more like rubber than a silcone sealant making it really easy to live with.

  23. I gave up on the front derailleur. We have 9 bikes in our household. Started the year with 5 front derailleurs. We’re down to 3. Goal is to go down to 1 front derailleur and 8 1by systems. The 1 front derailleur we’re keeping is DI2, thus worth riding. Everything else will go.

  24. #askgcntech what riding surface causes more tire wear? Gravel or tarmac? Assume same tire, same rider, same power, same tire pressure…

  25. The constant zwift advancements are that annoying that I decided to never buy a abo from them. Thes cunts have clearly overdone it!

  26. #AskGCNTech I've been wondering something pretty specific for a while. Can I convert my cyclocross/gravel bike to a passenger bike if i want to? what would I need to do for this? a rear wheel which can carry more weight? a rear rack seat? Would I be better off getting a trailer for the bike instead if I wanted to carry someone. I don't know if I'll actually do it but I really just think the idea of it is super fun. I have a Felt F65x.

  27. #AskGCNTech. Hi Guys, Thank you for the show, I love it!

    I see that you like the noisy freehub, when you review a bike you let it freewheel and enjoy the "music", but for me is just noise and it's annoying. 🙂
    I have a DT Swiss pawl freehub in which I put just a little bit more grease (I know it shouldn’t be too much) but didn't notice any difference. I have some DT Swiss red special grease (I know is for ratchet system) which is thicker. Should I try it? Or please tell me if there is anything that I can do to silent the freehub.

    Thank you!

  28. 3D print some blind cable entry pieces, that would take a bit of measuring, to replicate them, and maybe 3-4 test prints…

  29. The experience of recumbent riders is very relevant here. Many ride truly short cranks 130 not being uncommon, I use 143 the odd number being due to having long hollow cranks cut down. Always the same experience is that it takes 1000km or so for your legs to get used to it, many reports of tests on crank length are based on measuring the performance difference before the legs have relearnt the muscle memory. If you want to try shorter cranks then give it plenty of time before rushing to a judgement.

  30. got short legs (typical hungarian)- too often w/stock cranks (175 & 170 ) I felt I needed to adjust my position seat felt too low/too high, fore/aft – a bit frustrating to be honest- then, I tried 165s and felt dialed right in- hilly centuries /urban commutes. everything just works feels right from start to finish. the final sprint home even after a long ride gets the hr peaking max- double plus good, you know ?
    if you got issues like I did, it is worth the investment to try – the payoff will make you wish you tried sooner

  31. Before replacing the calipers:
    Sometimes when you take your wheel out of the frame, there's always a joker that presses the brake lever, maybe that happened to you..
    Remove the wheel and brakepads and with an 8 or 6mm allen ball wrench, carefully push the pistons back inside.
    Reinstall everything, reposition your caliper as shown in the video, brake a couple of times and test it again.

  32. Should buy some shorter cranks for my girlfriend, because she has the tities :))…..
    I just find it that shorter cranks are great only if you want a bit more of clearance when going in curbs like a maniac :))……

  33. lazy bike mechanic , the world is not flat ,, if it was everybody will ride on a single speed , when some bike company will come up with a affordable , light ,with less friction internal gear system , direleur will be gone

  34. @07:36 no it's not a requirement for disc brake either – many (older) bikes (mind included) with disc brakes work just fine with QR. I suspect most rim brake bike hold-outs are after wheel changing speed and that's the reason.

  35. Using longer cranks not only closes down the hip angle, it also tightens the knee angle. It has the same effect of reducing saddle height. If you swapped from 170 to 172.5 you would have to drop saddle by 2.5mm to maintain same knee bend. Then at the top of the stroke your knee is coming up an extra 2.5mm thus giving the effect of dropping saddle by 5mm therefore increasing load on knees.

  36. The 105 chainrings are not compatible with the R8000 crankset. I tried this about two weeks ago, and one of the Ultegra arms has a little "swoosh" that makes the 105 chain rings not fit.

  37. I've recently upgraded from 175 to 200 mm cranks on my mountainbike. Should have done this years ago. The amount of torque I can put out now is enormous. I am 2 metres 6, inseam is 104 cm. crancks should be 10% of you length, or 20% of your inseam.

  38. Knee Pain FYI: Shorter cranks (150-165mm) are often used with recumbents due to the rider being very fixed in position (i.e. no shifting/standing) and the not uncommon consequent knee pain that "regular" length cranks cause. For uprights, apart from the usual seat and pedal positioning solutions, this MAY be worth a try.

  39. I seem to be going against the flow since I prefer 175mm on my road bike over 172.5mm on my CX bike. However, I'm reluctant to change because the 2.5mm difference helps on the course in terms of clearance. It's also easier to ride sand since it's easier for me to hold the cadence.

  40. #AskGCNTech The weather is getting colder, and i notice that the shifting to smaller cogs and chain-rings are getting slower. Is there anything to do about that, other than waiting for warmer weather? I am running Shimano 105.

  41. #AskGCNTech When I let go of the handlebars I have to lean towards the right side to keep going straight. What can cause this? I have not had any crashes and have not changed anything on the bike. This has progressively been getting worse over the last year.

  42. Get the cassette, if you don’t have it. I put a 32t cassette on my 52/36 chainring and what a difference. 52×25 is no longer cross chained. 😀

  43. #ASKGCNTech Thank you for such a great show. One of the highlights of my day. I have a Canyon Aeroad that came with regular bar and stem. Looking for a 1 1/2" integrated carbon bar system and striking out. I live in the USA and Canyon does not ship here currently. Need help! Any recommendations?

  44. Hi!
    I have a bike-project going on, where i mean to mix different bike-components. I understand there is different lever and travel pull-ratios across shimanos range of different groupsets. Can you make a video comparing them, and their compatability with one another?
    #AskGCNTech

  45. Hi!
    I have a bike-project going on, where i mean to mix different bike-components. I understand there is different lever and travel pull-ratios across shimanos range of different groupsets. Can you make a video comparing them, and their compatability with one another?
    #AskGCNTech

  46. remember that with shorter cranks you will need to raise your saddle. A smaller crank will describe a smaller circle (pi x d) so your cadence will rise slightly. Wiggins used 170mm on his road bikes and he is over 6'

  47. Shorter cranks don't mean less torque at all. If we rode by just hanging a weight off the pedal then that might be true. But we ride by pushing the pedal with our foot, which is attached to our lower leg, which is attached to our upper leg, which is attached to our torso. It's all a system of levers at different angles, powered by muscles that have to contract, the performance of which is related to how far and fast they have to move, and ultimately limited (in anything other than a sprint) by your aerobic capacity.
    Even if you could argue that shorter cranks might have less torque, the counter argument is that you can spin a higher cadence for the same pedal force and pedal speed, meaning power is unaffected.

  48. Interesting how short cranks are now better for hip angle when for decades short people were told they'd get used to the same length someone five foot ten would be comfortable on.

  49. #askgcntech I have a Shimano 5800 front derailleur and the chain was rubbing on it while on the big ring and smallest cog on the back. Sorted the problem after watching Si's excellent video, though now I have to double click the STI level to get the chain in the small ring. Is it a trim function and can I get around it?

  50. Longer or shorter cranks? Let's look at this like we would decide what size of chainrings to equip. After all, the pedals are going around in circles, correct?

    In terms of efficiency, it takes more effort/energy to turn a 53 tooth chainring than a 50 tooth compact chainring. It easier to turn the small ring, thus less energy.

    A smaller crank will then be easier to spin around because its radius is shorter and is able to travel faster around its circumference, so you can maintain a high cadence longer.

  51. And Mickie Freiburg used SUPER long crank arms when he became a track cycling world champ, as this suited HIM at that time. We're all a bit weird and different from each other, so if one has the possibility try something new/different – go ahead!

  52. #AskGCNTech
    Hi, love the show!
    I'm looking in getting a CX bike, but I'm on a budget. So I'm looking in making a CX bike which I can use as a road bike as well. Would I be able to fit a 2x chainring on a sram 1x setup? And what other things should I know about?
    Thanks!

  53. #AskGCNTech It seems like road group sets are systematically more expensive than MTB ones. If you look at Shimano for example, it seems like the road parts are quite a bit more expensive at the entry level, the mid range and at the high end. Is it just the weight, or are there some other reason?

  54. tiagra cranks work just fine, the spacing difference is practically nothing. The same for mixing 5800/5800/9000 and 7000/8000/9100 cranks and FD, a half millimeter difference is nothing. The real question is why bother, 34/36 is only a 5 rpm difference in gearing. The cassette is more of where you should look, 32 or 34 in the back.

  55. For the guy that wanted grommets or plugs for his carbon frame holes he's no longer going to need, try a bit of plumber's putty. You can dye it (within reason), it's waterproof and, if you get sick of it, you can scoop it out with a dental pick and wipe it right off.

  56. Ollie mentions that with different crank lengths, altered torque doesn’t matter much because you can simply change gears. But isn’t it so that with a longer (crank) arm, you generate more torque with the same pedal force? Torque = force x arm. So changing gears is another matter? Of course, this is apart from the whole biomechanical issue, but still.

  57. Super like for the response about front derailleurs.
    Really, if you can't set-up a front mech maybe bike mechanic is not the right career.

  58. I know this is not so much a tech question but I'll ask anyway, On leg warmers how do you know what size you are?? The ones I have seen go in S/M or L/XL sizes, #AskGCNTech

  59. As a technical, nerdy engineer, I really enjoyed Ollie’s well thought out, detailed explanations on this episode. Thanks Ollie 🙂

  60. Hi Jon,

    I'd like to #AskGCNTech a question. I'm sure we all love our bikes to be as silent as possible and I've spent a lot of time making sure my bikes are properly "stealth" – no creaking from the BB, no rubbing on the front or rear mechs etc. But there's two recurring noise issues I have. 1) When out of the saddle sprinting or climbing hard, there is an odd "pinging" noise which comes from the rear wheel. It's almost as if the rear mech is hitting the spokes lightly but it happens no matter where the rear mech is on the cassette. 2) With deeper rim wheels, I've found that the valve stem rattles in the hole. Is there some way of fixing this? It's especially noticeable with very deep rim wheels where the rim itself seems to amplify the sound.

    Thanks in advance!

  61. About the disc rubbing and that tchk-tchk-tchk noise- I recently learned from another youtuber (Rides of Japan, bless his soul) that this, especially on downhills when the sound appears for no particular reason and then disappears by itself can be solved by thoroughly cleaning the callipers and especially the pistons.
    When pistons have accumulated dirt, they cant go back fast enough when they are hot due to the increased diameter due to higher temperature and the dirt makes the problem worse, that is why the sound disappears when the rotors and the callipers cool down. It is worth checking that if it turns out that the discs are true.

  62. Should you ride shorter cranks? No. What you should do is test various crank lenghts. My local shop had a power meter hooked up to a fit bike. I tested 175, 177.5, and 180 length cranks. The test was holding a harder pace for 5 minutes. Then look at what the heart rate was. 177.5s lowered my hearrate (for the same output/time) by 10% over 175s. 180 was only 5% better thann 175. Unfortunately no-one makes 177.5 anymore. So all my bikes have 180 (the next best thing). Oh, my inseam is 38 inches. Get the test done, find out what works best for your leg lenght and spin style. (The best way to cofirm results would be to do the test 3-ish times over a period of several weeks. It's also best to do the test mid season when your legs are in the zone – i.e. not at the end of the season when your legs are toast, not at the beginning of the season when you're legs aren't up to speed yet).

  63. Hello Jon…what are the differences in components of Shimano tiagra and Shimano 105 that should be considered while upgrading…hope you are back…love the show…#askgcntech

  64. I would like to inquire about something؟!
    Firstly. I am a novice in riding this biking rod.
    Secondly, I want an inquiry about how to run it for a big time and for a great distance every day I go by 6 kilometers but I can not run it for a large distance because myself short if I want an answer to all this please answer me as soon.

  65. #AskGCNTech LOVE the show! I'm looking to upgrade my bike with the Shimano 105 R7020 Hydraulic Disc but my bike from has post mounts does Shimano make Hydraulic post mount brakes that I can pair up with my new levers? thanks!

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