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Bike Tyre Pressure Explained | Road Bike Maintenance

Bike Tyre Pressure Explained | Road Bike Maintenance

– How hard should your tyres really be and what is the right pressure? The first point, if we’re
starting completely from scratch is to make sure that
you pump up your tyres to within the minimum and the maximum recommended pressure
that’s normally printed on the side of the tyre there. Now this one, this Continental, has a maximum recommended pressure only, that’s 8.5 bar or 120 PSI. So if you stick close to that, then you will not go wrong from a safety perspective, at least. If you don’t have a cycling specific pump with a pressure gauge on it, my first suggestion would
be to go and buy one but in the short-term,
what 100 PSI feels like, is actually when you squeeze
the side of the tyre, so not the tread, but the side, basically you can squeeze
as hard as you can with your thumbs and it
will not move very much. Ambiguous, I know, but you
haven’t got a pressure gauge, so what can you do? Well now we’re safe, that is
a very good place to start but it’s certainly not the
only thing to think about. We also need to factor
in the width of our tyres and also our body weight as well, because narrower tyres
need higher pressures than wider ones and heavier riders need higher pressures than lighter ones and then just to
complicate things further, we also need to factor in
the following points as well. (light music) Tyres need to grip, that’s pretty obvious, if you want to accelerate
or change direction or indeed slow down, but
a tyre that’s too hard won’t deform to the road surface and so less rubber will be in contact with the road at any one time, meaning that you have much less grip. So ideally, you want to run a pressure that allows the tyre to compress
when you sit on the bike. Now, believe it or not,
loads and loads of research has been done into exactly this topic and most people, it would seem, agree with the work of
a man called Frank Berto from back in the 80s and he worked out that the ideal amount of compression was 15% of the tire’s total
height, although admittedly, that is a remarkably
difficult thing to measure. (light music) Brilliantly, comfortable tyre pressures can also be faster tyre pressures as well because for just about
all of cycling eternity, we thought that harder
tyres were faster tyres and with good reason, to be fair, because in laboratory
settings, harder tyres were measurably much, much faster so they rolled with much less
resistance than softer tyres. However, out in the real world, on normal, bumpy roads, a softer tyre absorbs vibration much better and that vibration really
slows you down, a lot in fact. So, that is why a softer,
more comfortable tyre can potentially roll faster as well. (light music) If it’s starting to
sound like softer tyres are the way to go, then hold on, because a tyre that is too
soft will start to roll slower and then they will also
squirm around corners, which makes it particularly
difficult to control and dare I say, dangerous. And then also, of course, a softer tyre will be more
susceptible to impact punctures. (light music) I’m sure you’ll have noticed that I haven’t actually recommended
any tyre pressures yet so perhaps it is time for me to put my money where my mouth is, okay. I weigh 73 kilogrammes and
when I use a 23C wide tyre, I put 95 PSI in my front
wheel and 100 PSI in the back because there’s a little
bit more weight over there. And for 25’s, I use 80 and 85 PSI and then for 28’s, I run 60 and 65 PSI. As I mentioned earlier, if
you are a little bit lighter you will want to run less,
so consider putting in about one PSI less for every
one kilogramme of body weight and if you’re heavier, you
want to do the opposite. And if you’re working in bar, then that’s probably about one bar per 25 kilogrammes of body
weight that’s different. Now there are loads of
really handy calculators that are on the internet that will attempt to do this job for you
but if there’s one thing that I think you should
take from this video, it’s that you should spend time thinking about what your
own perfect tyre pressure is because it does vary from rider to rider and indeed, from place to place. So think about the things
that we’ve just covered in this video, does the tyre
squirm when it gets too soft? Or indeed, are you really
susceptible to pinch flats? Or, are you about to go for a ride on the best, most super smooth
tarmac in the entire world? In which case, you probably
want to put a few extra PSI in. Do not be afraid to play around, stay within the limits and stay safe. Oh, and there is also one thing, it’s not just your tyre that
will have pressure limits on. If you’ve got a really
lightweight set of wheels on, then they too may have a pressure limit although, if they’re anything
like these Zipp’s here, we’ve actually seen them being inflated to over 200 PSI more than
the recommended limit. (explosion) Whoa. Well clearly, a little bit of margin for error built in there. Now, do make sure you subscribe to GCN, it’s very simple and it’s free to do it, just click on the globe
and if you’re after some more content, about tyres in fact, then why not click up there and we’ve got a video about
how to reduce the risk of punctures, or just down there, we’ve got a very topical one, the truth about wide rims and wide tyres. Check ’em out.

100 comments on “Bike Tyre Pressure Explained | Road Bike Maintenance

  1. @GCN sitting in the lunch room at work and ate some feta cheese off my shirt, turns out it it was a piece of deodorant. How's your day going ?

  2. love the show. ok so this is nothing to do with this video, but i was wondering have you done any episodes to do with putting a water bottle under the down tube? i have seen pictures of people putting them there how are they doing it?

  3. If you were riding a short race would you put more pressure in your tyres than if you were doing an all dayer? i.e. you can put up with a bit of discomfort for more speed if you're only going to be in the saddle for 40 minutes or so?

  4. About the vibrations on rough roads. One extreme is a Dutch bike path with a near perfect flat surface, which is very fast. The other extreme is a stretch of Roubaix style cobbles, which is way slower. Almost everything sits in between these two. Interested to know what the difference is in Watts to sustain the same speed on different road surfaces! Everyone knows the difference is there – any chance of quantifying this? It'd be an important input for the tire pressure setting #torqueback #gcndoesscience

  5. Very cool Si, I weigh 15kg more than you (not so cool) but I should set my 25C tires up like you set your 23C tires. That makes it easy.

  6. According to your math 63kg I should run 28c tires at 50/55 psi. That seems really low… I'll give it a try, but from experience it feels like that pressure gets you too close to pinch flats on anything but perfectly smooth roads. Is there potentially a limit to the framework you're suggesting in the table at 3:39?

  7. If I've got a Canyon Aeroad (like the one in the video), which comes with 23mm Front and 25mm Rear, what pressures would you recommend?! I'm 72kg, so roughly the same as Si…

  8. So I watched this video when it was posted last month, yesterday my new 700×25 Vittoria Rubino Pros arrived; and this gets me to ask: What about going below the min pressure when the min is listed as 100 psi (they are labeled "100-130 psi")? I'd like to run them lower and I can't image pinch-flats or squirmy tires at 90 psi. I'm mounting the new tires today, but with cold & snow in the forecast, I'll likely be riding the fatbike (at 12.5) psi for the next few days.

  9. I'm 280 lbs I am wondering about tire pressure on a gravel bike. I don't own one yet but thats the way I'm leaning. I guess I will have to run the widest tire I can fit on whatever bike I get. a few online calculators are telling me I will need 200 psi in the rear wheel, that cant be right can it?

  10. Does the inner tube size also matter when determining pressure? I run a Conti GP4000iiS 28mm with inner 700cx19-25 tube

  11. Global Cycling Network Can you please explain 1:00–1:11? ive watched that clip over 20 times now and i still dont understand.

  12. I think there's an error in his math.  1 bar = 14.5 psi, so that would be 1 bar for every 14.5 kg of "extra" body weight. 

    Using Si's 23mm tire example, at 73kg he would use 6.895 bar Rear, and 6.55 bar for Front.  If you weight 87.5 kg you would use 7.895 bar Rear, and 7.55 bar for the Front.

  13. hello sir can i ask something about road bike tires… which is the better size in roadbike…. cause i wanna buy bike..its my first time

  14. Sheez , that's low , guess I've been completely wrong with 9 bars for a 63 kg body weight . Mind boggling stuff

  15. Running higher psi can be more comfortable if your frame has flexible vibration absorption built into the frame . I have tried 85 psi on my evo with 25c tyres, then 115 psi only to find the latter more comfortable strangely enough. I can only conclude that the harder tyre forces the frame to flex or work the way it was ment to. Anyone experienced the same?

  16. Body weight of 72 kg, and was running 28c Gatorskins at between 8.5 and 9 bars (126-128 PSI) on a new Giant Contend (alloy frame) under the impression that maxing out pressure would result in fastest possible ride. Just dialed it back to 8 bars (116 PSI) yesterday, and it made a world of difference. Took the "teeth-chattering" edge off the ride, felt more sure-footed when cornering, and I actually rode a bit faster over the course of my 40k ride. Much of that speed gain took place in the 2nd half of the ride, perhaps as a result of feeling less "beaten up".

  17. Hum… So did you improve your knowledge since July/2016 that made you change your previous opinion? I ask because in this July/2016 video ( you state that for a 70kg rider with a 25C tyre you would use 95psi. On the video above you state that for 73kg rider on a 25C tyre you would use 80psi front and 85psi rear.
    Well, you did say that "no one knows what the right pressure is" however if you intend giving some sort of rule of thumb, then you should either keep some consistency or, in light of new information/knowledge, on a newer video make a claim that the information here contained supersedes the information contained in a previous video.
    One last thing, and bearing in mind that you did say say within the interval of manufacturer recommend tyre pressure, I have a 28C Mavic Yksion on my bike and that interval is 87psi (min) – 116psi (max), thus I could never use the 60/65psi you recommend on the above video, could I?

  18. I broke my derailleur on my road bike and since I didn't have any replacement so i put my saint derailleur on and it works great

  19. You are not completely right.
    The weight distribution for road bikes is about 45:55 % front:rear, so the front tyre pressure should be about 20% lower. Works not only for comfort but also for equal grip. The same principle as for the cars.
    Also the higher pressure means lower grip, thus corning becomes slower. Sometimes much slower. The same works for cars.
    With equal pressure You lose the front wheel on cornering, it's so hated understeering (remember cars!).
    For best rolling to grip ratio road bike tyre must have contact to tarmac about 2/3 tyre width.
    My bike usually inflated to 6.0 and 7.5 bar or 85 and 107 psi front and rear (tyres 25 mm, rider 90 kg). +0.5 bar means less comfort and noticeable less grip on corners, but not sensibly better rolling.

  20. I've usually gone until they are just hard, which is in the 30s LMAO. My bike tires say to have double that i think. It's been awhile

  21. Si, great video . Do you run Conti 25 mm in the front also, or do you run a 23 mm front for aerodynmics?
    I know tis would also vary with road conditions. Thanks to you and GCN !

  22. Who here runs 23mm front and 25mm rear ? Do you guys see any advantages?
    Thinking of going that route to be slightly more aero , but wondering if 25mm on both is better .

  23. In regards to high tire pressure and bouncing of rough pavement; A tire that's not in contact with the road has ZERO rolling resistance. Within the bounds of safety, higher pressures on rough pavement may not effect rolling resistance negatively as the the higher rolling resistance over rough pavement and the zero rolling resistance of reduced contact equalize data.

  24. What about if your running the new Gran Prix 4000s Attack 23 C front tyre & Force 25C rear tyres. What pressure recommended for this setup if rider is 70 Kg ?

  25. Hi , would like to know if there is any different between clincher and tubular in terms of pressure? I'm around 74kg, what is the normal pressure for my 25c tubular Tyre (Continental competition – max 165psi) ? Thanks

  26. Im usin 103 psi in the back and 98psi in the front with conti gp4000s 23mm.
    Though my roadpaths are rather nice they are far from fine smooth tarmac, that relatively high pressure is the fastest for me(i weigh 70kg and measured that with my powermeter)

  27. In the chart you show weight in Kilograms (metric) and tyre pressure in pounds per square inch (psi, Imperial). Keep it consistent and use metric for both (kg, bar) so it‘s easier to calculate how bodyweight adds to pressure.

  28. Question. Although a tire is 25 mm, it actually measures larger when mounted on a wheel. For example: Continental 25 mm 4000II measures around 28 mm on a wheel with a 19 mm inner diameter. Which number do you use to decide the correct psi in this example: the number printed on the sidewall or the actual diameter of the tire when installed on the wheel?

  29. Ive got 25c tires and Im a light rider of around 58kg, whats the best pressure for riding a smooth, closed circuit criterium race??

  30. Great video, thanks. Turns out I've been setting my tire pressure spot on to Si's recommendations. My question, why does a smaller change in tire diameter equate to a significantly lower recommended tire pressure? I roll on on 25s, live in the city, weigh 88kg with pressure at 95/100. Chicago's harsh winters equate to harsh roads, plus debris, etc. Many of the cyclists I've chatted with are recommending 28s for comfort and better puncture resistance. So…a 12% increase in diameter (25 to 28) brings my recommended PSI down 20% (100 to 80)…the question is, why? Why is there a sharp drop in air pressure for a very small increase in diameter? (PS – had two pinch flats last week, 1 spare tube, 0 patches. Immediately with the 2nd flat I heard you guys on replay in my mind from another video, "carry two tubes.") Great channel, thanks.

  31. do you need to take the weight of the bike and water bottles into consideration in addition to body weight ? that might add around 8 to 10 kg

  32. 90Psi seems to be my sweet spot feels good grips good comfortable as well. Used to be 120psi and it was just jaw shattering and numbness in my hands in 30mins. Now i can go as long as I want without much numbing at all.

  33. Interesting Simon recommends much lower tire pressure in the rear tire than all the online calculators. For him say bike + rider weight 182 lbs, front tire 60 psi, rear 74 psi for 28mm and thats for 45/55% weight distribution. 40/60% would be 52/81 psi for Simon NOT 60/65 as he recommends. Guess Simon never runs over potholes so he doesn't worry about pinch flats.

  34. For us normal people of the past (Im 68) we always used a " vintage hand pump" that clipped under the top bar. We screwed the flexing screw tube thingy on the tyre valve and pumped till the tyre got hard (ish). We then rode the bike. There were no gauges but we seemed to get on just fine. Should I change my ways or just carry on as I am? ATB. Pete

  35. The tires on my motorcycle are significantly fatter than my road bike, so this wider tire thing must be true.

  36. this channel is grievously unscientific. what if I lift weights and my grip strenght is higher than you? would I not push the tires together at higher psi? I guess stupidity is what is required to be a member of this culture. thats my conclusion anyway after spending half a day trying to research cost efficiency on a road bicycle purchase. bicycle manufacturers have no incentive to create the optimal road bicycle once and for all (and compete in manufacturing costs), so they invent niches and a continuously larger stock of options to crowd the fact that there is no real improvement. heck, the optimal way of cycling from an enginering perspective is recumbant, but cycleheads are sheep following a sport regulation structure. this creates an industry and infrastructure with millions of non-optimal commuters based on "the feeling of your bike". the math is simple guys – wattage in, distance/speed out.

  37. On British roads soft wide "tyres'', as you like to call them, do really make sense. In central Europe we have awesome roads compared to what you have, and i feel faster on 23c 120 Psi.

  38. Ha!!! Finally I have proof. My husband was always pumping my tires more than I wanted, even though I argued that it felt better at a lower psi. Your recommendations were exactly the psi I preferred. Of course it's our weight difference…duh! Feels so good to be right once in a while….

  39. Brontager hard case lite say 80-115 psi …but I weight 78kg and according to your numbers I should put 65front and 70 back ..but this is outside there recommend as on the tyre ???? 28mm tyre

  40. that terrible UK tarmac. here in switzerland and italy the tarmac is all super smooth so you don't need to worry about bouncing around with high pressures.

  41. why and how do tyres lose air pressure?

    also why do I seem to ride a LOT faster with a lot less effort at lower pressure, and Im talking about 30-40 psi which is much lower than any of these videos suggest

  42. What if the tyres have minimum tyre pressure on (110psi). It says 110-125 psi.. which is significantly higher than the recommendation at the end of the video

  43. I have a fat bike. 30 psi max is mentioned on the tyres. Should I go with 30 psi on smooth tarmac highway? I have seen in few videos that we should fill 10% less air than the max. Please suggest

  44. Yet Another awesome and very informative video Si !!!! You are the best !!!! Thank you, you are my favorite GCN presenter…. Although Ollie is getting up there fast…

  45. My Rubina Pro 25c-622 bike tires say "min 100psi, max 130psi". I see a lot of recommendations for setting 25c tires to 80-85psi. So, does this mean I still need to inflate my tires to no less than 100psi?

  46. sooooo i have a trekking bike and at the moment my tires are kenda multitrack sport 35c with max bar 5.9 and i am weight 76kg. Is it right to put them at 5 bar?

  47. what psi for wider rims? latest wheels are wider rims and wondered if low PSI necessary due to potential changes in volume of air.

  48. A simple real-world experiment to test tyre pressure energy loss etc…
    Find a “U” shaped hill (Down and back up).  Do experiment on a non-windy day.  1.    Fit first set of tyres to bike. From a specific place, freewheel down the hill and back up the other side until you stop. Record the distance travelled. Repeat three times and take average distance.
    2. Repeat the experiment with different tyres / pressures / wheels etc.

     Longer distance back up the hill = less energy loss. Simple!

    NB always start from the same point and use the same riding position, rider & clothing. (in theory the only variable will be the tyres / pressures / wheels etc).
    This method can also be used to measure just about anything where rider inputs no energy e.g. Lycra skinsuit vs woolly jumper.  It’s basically a real world combination of wind tunnel and road surface.  Why simulate when you can do the real thing??!!

  49. I'm very overweight and have been setting my tires to 570psi to compensate but they still look flat when I get on

  50. All hot air.
    I weigh 92 kilos and my bike weighs 23 kilos, so riding on both pavement and dirt at an average speed of 20 mph and the tempeture is 23 celcuius with bright sunshine and a 5 mph wind speed with a 2.5 inch tire that deflects 2.5 millimeters during a low pressure and in a bad mood , i would need approx. 42.56892 psi.

  51. I wonder if there are any wheel builders out there? Looking for some advice please. I have a tandem. When the back wheel is 7 bar the true is perfect and the rim does not touch the brake bloks. When the back wheel is pumped to 8 bar the true goes out a bit and the rim starts rubbing on the break blocks. I had to use 8 bar because together the pilot and I wheigh a bit more than 150kg. Maybe the wheel needs to be trued when invlated to 8bar? I'm suspecting that some spokes are not set tight enough. Please advise if you could. O, they are Bond Rager 24 spoke wheels.

  52. you don't ever just run a set of tyres at max, what you want is a small amount of compliance in the sidewall and it all depends on the load they have to carry.

  53. I had a blowout a week after I got the bike back from the shop truing the rear wheel. I think they nicked the tube.

  54. Well my tube exploded. I weigh 75kgs and decided to pump to 90psi because of that and it turns out tubes from big W don't hold that much pressure

  55. I have 23c tires and use 100 front and 100 rear… I weigh 58kg It feels terrible… but I like the smoothness on the tarmac

  56. Im 67 kg and running on a 20c tyres, does it mean i should pump those up to like 110-front; 105-rear?

    And yeah what about 18c and 20c tyres, or those are not even intended for a daily use?

  57. Fantastic info especially, for someone, who's decided to try biking instead of walking an, running,, love your video's,,

  58. I run 55 psi front 60 rear on my hybrid, I still average the same 17 mph. My tire are 32mm, did the same test at 85 psi. The ride was much harsher, and I almost crashed when the tire hit the edge of the road. Needless to say, I no longer run on max PSI. I'm 62 kg.

  59. I Weigh in 50Kg, and I absolutely CANNOT imagine myself riding 60-65 on my 25c hahaha i pump it up to 90-95, bike just feels solid, and i have 0 punctures.

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