Peer Pressure

What's your ride number?
What’s your ride number?

Eight point V bar. From the moment I bought my first set of high quality road clinchers, I’ve ridden at that pressure. I started with that number because that’s the pressure the sidewall told me to pump them up to; I didn’t yet understand much about balancing the benefits of high and low pressures to optimize comfort and friction; I just pumped them up as instructed and off I went merrily down the road.

I’m not as thin as I’d like to be, which is the same thing as saying I’m fatter than I should be, though I certainly hope I climb well for my weight, especially as my third (and hopefully charmed) ascent up Haleakala is looming large in Vajanuary. The point is, I’m not a whippet and even if I starved myself for the next five months and subsist exclusively on IPAs (I draw the line at cutting beer out of my theoretical diet; I might get desperate, but I’m no savage) I’d still be an Eros Poli at best. Being a big guy, the only factor that mattered to me when it came to tire pressure was avoiding the pinch flats that plagued me during my time riding cheaper tires and that meant maximum pressure, no questions asked.

We always dialed our pressure in for Mountain biking and would pull a few pounds out of our road tires when riding in the rain, but by and large, tire pressure was tire pressure, and as far as I was concerned, more was better. I even had a set of 20mm tires on a makeshift TT bike I had that I blew up to a whopping 10 bar. In the last few years, however, the Cycling world has become obsessed with doing the limbo and seeing how low they can go on tire pressure. It all began with an article in Bicycle Quarterly which conducted an extensive and flawed study on the effects of tire pressure and tire width, and concluded that lower pressure and wider tires are faster and more comfortable than high pressure, narrow tires; the idea is that lower pressure allows small bumps to be absorbed by the tire rather than bouncing the bicycle (and rider) in the air, and that wide tires flex more efficiently than narrow tires resulting in lower rolling resistance. Its important to remember that this gain in comfort and efficiency also comes with an increased risk of pinch flats.

This is all well and good, of course, though we always have to be careful to remember the basic principles of such a compromise; lower pressure and wider tires also mean an enlarged surface area which necessarily means more friction; a perfectly hard, narrow tire on a perfectly smooth surface would have almost zero friction, to the point that you’d be unable to gain enough traction to actually move the bicycle at all. What we’re after, in a practical sense, is a balance between the two extremes which optimizes comfort and tire efficiency against reduced surface area and the risk of pinch flats.

I became infected with Tire Pressure Fever myself as the Cycling world became increasingly obsessed with tire pressure. Down went the pressure in my tires and immediately I felt sluggish and lethargic on the bike. Climbing out of the saddle, I could feel the tires flex as I unleashed the Awesome Devastation of the Toothpicks of Navarone. Cornering was like steering in molasses; turn the bars, weight the pedals and then wait a few moments while the bike got round to responding.

These observations first had me reaching for the pump and then got me theorizing about what is really going on with tire pressure and what pressure is right for a given rider. I say “theorizing”, but most other people would use something closer to “guessing assertively”. But that doesn’t mean I’m wrong.

Basically, it comes down to finding the highest pressure and narrowest tire you can that gives a rider of your weight the right amount of tire flex such that your bike isn’t bouncing as it rolls over the tarmac and allows it to roll efficiently, all while minimizing surface area, risk of punctures, and sidewall deformation when accelerating (cornering and climbing are basically the same as accelerating; the acceleration vector is just in some other direction than forward.) This means that each rider at each weight with different preferences on the sliding scale between the above compromises will find a different optimal pressure. Impressed by Tom Boonen’s tire pressure at Roubaix? Tread carefully; that pressure was dialed in based on very specific criteria and unless you’re eating the same cobbles and weigh the same as he does, you’ll need a different pressure to find the same balance. Bicycle Quarterly has a chart that shows what they believe to be the ideal pressure by rider weight, though I don’t believe a word of it; I do however entertain the possibility that I could be missing something based on the fact that I didn’t actually read the article.

Me? I’m still happily riding at 8 point V. I’m comfortable, I’m not flatting, and I’ve got good control. Besides, it just has a nice ring to it.

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145 Replies to “Peer Pressure”

  1. I experimented with this extensively over the last year.  I basically pumped my tires up to 120 and then didn’t add air until I would occasionally feel the rim hit the ground on bumps.  

     

    Results:

    I did this for a year and have nothing to add to the conversation other than the fact that I did it and continue to do it mostly due to laziness now.  Only pinch flatted once when I didn’t see a large rock in the dappled sunlight.

  2. Frankly Frank as long as the rims aren’t running on the tar I’m fine! Being probably even worse than most of you in the “too fat to climb” camp (215lbs when toweled bone dry, and it’s not like I can blame freakishly overdeveloped biceps and pecs) sometimes even 10bar wouldn’t be enough to stop the black bits bulging.

  3. I’ve settled on 7 on the front and 8 on the back. They probably drop to around 6 and 7 bar before they get pumped up again.

    I’m currently riding 25mm’s on my now N2 and will do for the rest of the winter, the bigger the cushion the sweeter the pushing.

    My new N1 has got Conti Attack / Force that are 22mm on the front & 24mm on the back. The bike is fast but I’m undecided on them.

  4. I prefer something closer to 7 point oh V bar.  I don’t think it was mentioned (I didn’t read very carefully) but the front tire gets about point V less bar than the rear.

  5. Nice one, Franki Poli! And really slick lead photo. Mmm, low profile rims & plenty o’ spokes.

    I’ve actually never been that concerned with tire pressure. I inflated until they feel pretty darn hard to the squeeze, far from scientific, and then head out. I know, a potentially unacceptable method for a Follower. I do inflated my front tire less but in general I ignore the dial on the Park Tool pump since I don’t know if it’s that accurate. Then again, I ain’t so big which might make pinch flats less of a concern. I do however remember my first pinch flat on a road bike, which occurred on a sidewalk in Washington, DC. That’ll teach me to ride on darn sidewalks.

    I do now pay more attention to tire pressure on my CX bike, set up tubeless. Oh, and I think I’ll try out some 25s next time I invest in new tires. For now I have a big stock of 23 mm road tires.

    Michael, your method has me feeling a lot less bad about myself…

  6. If only all the tubes, if you will, who rode on pavements (or sidewalks if you prefer) got pinch flats then the world would be a better place.

    Ron,

    That is a perfectly acceptable way of checking tyre (note TYRE) pressure, if they were bigger as in a farm tractor size I would kick them but I don’t want to risk damaging my baby. So I use the squeeze test as well, but I’m not sure if I should recalibrate the pinch between wearing mitts and full on winter gloves.

  7. rule of thumb to start from: 1 bar for each 10kg of rider’s weight. easy!

    @motor city i’m also running the conti force / attack set. 8 bar in front, 7 point V on the back. great grip cornering!

  8. I got turned on to 25mm tires a few years ago and have never looked back. I ride both clincher and tubular 25s.  High quality 25s are nearly as light as 23s but they roll faster, corner better and last longer than thinner tires. The extra comfort doesn’t hurt either. I’ve tried 28s but got that sluggish feeling from the front end trail getting all goofed up. Next set you buy, get 25s.

  9. @Cheaves

    I got turned on to 25mm tires a few years ago and have never looked back. I ride both clincher and tubular 25s. High quality 25s are nearly as light as 23s but they roll faster, corner better and last longer than thinner tires. The extra comfort doesn’t hurt either. I’ve tried 28s but got that sluggish feeling from the front end trail getting all goofed up. Next set you buy, get 25s.

    I’m a 25mm tire man myself, but I don’t know that I believe they roll faster, corner better or last longer than thinner tires.  I ride them exclusively because the roads I ride are complete shit more often than not and with a 25 I can run slightly less pressure than I could with a 23 without pinch flatting and the comfort that comes with that is noticeable to me (for reference I’m 90 point V kg kitted up and run approximately 7 point V in the rear and 6 point V in the front).  I’ve even purchased a set of in-fashion 23mm rims that I intend to run 25s on just to drop the pressure a little bit lower.  I also bought a pair of Bonts after @frank’s Vaypor article so you could say that I’m definitely a slave to peer pressure.

  10. Have and always ran at max pressure tyre label says. Love to give the tyres a flick and hear the pinging sound!

    What’s interesting is tyre width. I’ve gone 18, 20 & 23. Found that 18 was too harsh riding on, but for racing OK. Enjoying 23’s and am in the market for some new tyres. Anyone like 25’s over 23’s? Melbourne roadssurfaces are generally good, it’s the friggin population growth of pot holes that get you!

  11. When I got back on the bike last year, after a long time in distant lands, I was amazed to hear of this business with fat tires (25mm!) and low pressures. I went from various 23mm tires at max pressures to 25mm 4000GPs’s at a semi-flaccid 6.5 (I’m 75kg) and am SO HAPPY  on the local chipseal.  And while I never felt “fast,” I don’t feel any “slower.” Nor any more panic-stricken than normal on twisty descents.

  12. 700 x 25C front and back, 7 bar each. MUST pump and check before EVERY ride, -my OCD.

    7×10=70, yes I actually weigh 70 kg, never thought about that. Hope I will not need to increase tube pressure after X-mas.

  13. @frank

    you’ll need a different pressure to find the same balance. Bicycle Quarterly has a chart that shows what they believe to be the ideal pressure by rider weight, though I don’t believe a word of it, though its possible I could be missing something based on the fact that I didn’t actually read the article.

    It’s good you didn’t read the article or look at the chart because it would lead you to believe you were over inflated. According to the chart I should be at 4.5/7.0 bar for 25mm tyres and I’m a big fella. Either way, a subject better discussed over pints. That will happen soon enough, friendo.

  14. We wrote on this in the summer when I did my back and you all (Oli) figured that it was caused by me running my Fortezzas at the full 145 rating. This extra vibration even through a Ridley carbone frame sent my sciatic nerve over the edge and me with it.

    I also had a front tyre blow out descending the Duke’s Pass caused by the heat from my rims taking the pressure way over 145psi. Obviously if I didn’t descent like a fairy boy my rims would run cooler but that’s another story for another day.

    I run things around the 90 mark now (on medical and LBS advice) and all seems well.

  15. I have been riding 25mm tires mostly for the past couple of years.  Prior to that it was 23mm tires.  To be more precise, I am riding 23/25mm tires.  I have been riding Specialized Roubaix Pro tires and I will attest that they make for a smooth ride, but they are still pretty darn fast.  Their marketing spiel states that the 25mm comes from the way that they add some additional thickness to the tread.  All I know is that they give a comfortable and fast ride, and I haven’t flatted in more than two full seasons of riding on them.  And they are inflated to about 8 point V bars…

  16. I like 6.5 bar front and back on 25mm tires. Any more than that and I feel like I’m getting bounced all over the place on crap roads, any less than 6 feels sluggish to me. sayin’ that I’m only 64 kilos

  17. my pressure depends on the bike and tires (i’m not writing tire with a ‘y’ in it. it just looks wrong to me.  sorry.  can’t put a ‘u’ in color either.).  i keep 23’s (conti 4000s) on my carbon bike; the one with all the lightest components i own on it that comes out for the summer and *definitely* comes out for fast club rides.  those 23’s are mounted to 19mm wide hoops.  i keep 25’s (conti 4seasons) on my steel bike; i.e. the winter/bad weather/long distance bike with a bit heavier components, more relaxed position, focused on durability and comfort over long, possibly rough rides.  the 25’s are mounted to 23mm wide hoops.  i weigh around 68kg.  and it sounds like i follow the “1 bar per 10kg rule” in general.  the 23’s get 7.5 bar back, 7 bar front.  the 25’s get 7 bar back, 6.5 front.  (wet weather gets about .5-1 bar lower for both bikes.)  i’ve run lower and i’ve run higher, but i don’t like to go any higher than 7.5 bar.  i definitely notice a downgrade in comfort when i go above that.  i don’t notice a large difference if i go down to 6.  but i think this might be a combination of the tires and rider weight.

    anyway, frank’s right that it’s worth investigating.  and i think it will all depend on the rider and bike combination.  but in general, i’m running at least 1 bar less than i was a couple years ago.  my last pinch flat was well over 16000km ago; and that one came on a fast, 60+kph descent when i hit a large pothole, so i doubt the pinch could’ve been avoided.

    gotta say though; wider rims with 25’s is by far my favorite way to ride.  i’ll swap my 23mm wide wheels with 25’s on them over to my carbon bike occasionally and the ride is definitely improved. not just on bad roads, but all around.  and in the wet, i really notice a difference in grip and comfort.

  18. The little unsung hero in all of this, she to gives us peace of mind and allows the  “V” to fly each day. Thanks Frank nice post and for the rest of the contributing Velominati. With the harsh chipseal roads i now ride on, the 25s are sounding pretty good. I have already dropped air in both tyres to help until i visit the LBS .

  19. I too ride on 25’s… Michelin PRO4 Service Course at 7pointV bar. I like.

  20. Great piece, man. Lowering pressure makes a lot of sense in terms of lowering rolling resistance, softening the ride, and cornering confidence especially on rough, wet, or uneven roads. I moved fully away from 8.5 bar riding this year and am now in the 7 range in rear and 6.5 in front. The only thing I’ve felt is more comfort and cornering confidence, in other words, no mushiness. If anything my speeds have increased but that’s due to much more than tyre presh. The 23 v 25 dilemma is solved with OPEN Pavé 24’s. Man those are nice and the perfect width tyre. I wish they were a bit more durable but by far my favorite tyre for everyday and a true hardman’s tire. I’m not worthy.

  21. @freddy

    I too ride on 25″²s… Michelin PRO4 Service Course at 7pointV bar. I like.

    I had been a fairly regular Michelin user but got the Pro4 SC (23mm) and had more flats than rides.

    Junked them after a week, haven’t used Michelin since. Back to Vredestein if I can get them and Conti 4000S if I can’t (because that’s what they stock out here).

    I tend to keep my tyres at least 125 psi / 8.5 bar here, which is about in line the 10 kg rule.

    The main flat danger is the little bits of metal, about the size and width of a staple, which get shredded from truck tyres. Plus the roads have many, many square cateyes which will cause a pinch flat. We don’t have (much) rain, the cornering is mostly through roundabouts.

    Horses for courses.

  22. @ChrisO

    @freddy

    I too ride on 25″²s… Michelin PRO4 Service Course at 7pointV bar. I like.

    I had been a fairly regular Michelin user but got the Pro4 SC (23mm) and had more flats than rides.

    I’ll clarify…I like the ride–not the flats. I thought it was bad luck, but your report is making me think otherwise…

  23. Now I know why I am getting lots of flats lately.  I never thought the pressure would be the solution.

    I have been running 23mm gaterskin tyres at the rim max of 110psi since I had them, but recently took a spill on a corner in the rain (A badass practicing Rule #9 but learning about the reduction of cornering confidence as described in Rule #64)  and decided that I would experiment with lower pressure at 100psi.  I really liked the lack of vibration, but have had 5 pinch flats on the back wheel in a week.  According to the chart, I should be running about 155psi on the rear (100kg with a 60% load on the rear.)

    I I think I will go back to the proven 110psi on the rear, and might leave the front at 100psi.  That should fix it!

    BTW: does anyone else have trouble getting gaterskins to run round after changing them?  Mine like to bulge and take a bit of a fiddle to seated again.  What do you do?

  24. Mmmmmm   interesting reading …….  appears to be no “Standard Operating Procedure” here …..

    Running 23mm Conti GP4000s up front @ 95 psi and 25 mm Conti GP4000s out back at 90 psi ……. why …… i dont know ……  just feels right …..

    Plus I like the sound of different tyres and pressures as it assumes I have thought about some mystical reason for doing so.

    “if you cant play the game, least look like you can”  ………

    25’s definately give a smoother ride or our crappy South Oz roads. But I like the 23 up front as it gives great response.

  25. This is something I have always struggled with. On the Carbon steed I usually go 7.4 and 7. on the steel bike I go a bit less(I really want 25mm tires on this bike as its just a get around bike)

    Today I pumped the 29er tubeless tires to 2 bars, and that felt like a bit much on the trail.

    Im thinking I need to revisit my strategy on this.

  26. @Barracuda

    There is a good thought. 23mm front and 25mm back. That makes a lot of sense. Personally I like 25s front too to avoid pinch flats but I do like your idea of mixing it up. I think someone already said it but that maybe what those Michelin Optima tyres are all about with their dedicated front and back.

  27. @RedRanger

    Nah, I’d suggest that’s about right. What width tire you running?

    FTR, I’m 70kg, run tubeless 2.25’s with 28psi.

  28. One day we will have a full Velominati conference with hundreds of svelte sub 100kg sticklings in lycra waxing lyrical about all things light, bright and fast.  I will stand there like a “man mountain”.  I am Eros Poli….but without the engine and with the corresponding girth to make me look normal.

    This discussion confuses me a little, I think the time would be better spent praying to the God of Snakebite Flats (GSF) and sarcrificing vestal virgins on altars made from worn out tyres.

    I roll on 23mm Gator Skins at 120psi (er…think that is about 8.2bar).  My fighting weight is a good chunk north of 100kgs and I flat maybe 3 times per year.  I swap out and crack on with ner a thought for it, dink a cheeky wink at GSF and say “you got me today old man….but I am looking forward to sacrificing double the amount of virgins tonight!”

    Where did science ever come in to it?  The secret is to watch where you are going surely?…

  29. The bastard chart stops at 70Kg what use is that? According to the 10Kg/1bar rule of thumb my tyres shout be at around 90bar :(  .

  30. @E Unless you’re riding a unicycle, you should be OK, it’s a 70kg wheel load not rider weight.

    If you are on a unicycle  you may be on the wrong site. Each to their own, though.

  31. @E

    The bastard chart stops at 70Kg what use is that? According to the 10Kg/1bar rule of thumb my tyres shout be at around 90bar :( .

    I feel your pain – mine would have so much pressure in them that metallic hydrogen would form and/or nuclear fusion would take place.

    And don’t let Frank catch you using emoticons or you will be in a world of shit…colon hyphen close brackets irony

  32. @Batman

    I I think I will go back to the proven 110psi on the rear, and might leave the front at 100psi. That should fix it!

    have you considered the idea that gatorskins are awful in the rain?  that would likely explain your crash; or at least part of it.  they’re very robust tires for flat resistance (when the pressure’s right!) but not treaded well for wet weather.  or at least not as good as other tires.  i’ve heard people even say they should be illegal in wet weather!

  33. @Gianni

    @Barracuda

    There is a good thought. 23mm front and 25mm back. That makes a lot of sense. Personally I like 25s front too to avoid pinch flats but I do like your idea of mixing it up. I think someone already said it but that maybe what those Michelin Optima tyres are all about with their dedicated front and back.

    On my cross bike road wheels I have this setup, 25 out back, 23 in front. I like it but the main reason for this orientation is that I happened to have these two extra tyres on hand. Wouldn’t mind trying it out with 25s on both, but maybe 23/25 is good for me, especially since I relatively light.

  34. And Peer Pressure? Hell yes. Any of us adhering to The Rules is being kept in line by some common sense, a reverence for some decency, an appreciation for tradition, and, of course, a willingness to do some stuff just ’cause it seems to work and keeps ya lookin’ cool.!

  35. I usually run around 110 psi in my Ultremo R1’s, and if its lower than that for any reason, I obsess the entire ride about how my “V” is not achieving it’s full potential due to the increase in friction; about how my tires are overheating and wearing prematurely, and if they do wear out, how I’ll never be able to afford to buy them again. I think I should switch to a less expensive pair I have sitting in my basement, but I’m too lazy for that.

  36. @chiasticon

    @Batman

    I I think I will go back to the proven 110psi on the rear, and might leave the front at 100psi. That should fix it!

    have you considered the idea that gatorskins are awful in the rain? that would likely explain your crash; or at least part of it. they’re very robust tires for flat resistance (when the pressure’s right!) but not treaded well for wet weather. or at least not as good as other tires. i’ve heard people even say they should be illegal in wet weather!

    I think you will find that what is given with one hand is always taken away with the other.  Personally I love my Gators, the rolling resistance is relatively low, the puncture resistance is good if you look where you are going and I am always very careful in the wet on corners…I would imagine human error is far more likely here that the difference between a gatorskin or any other tyre for that matter….some days you can spank that corner in the wet and get away with it….other days you can’t….there are too many variables to be that simplistic, oil or grease, leaves, gravel, angle of attack, movement of bars to name but a few…

    I would suggest stick with the gators till they are worn out, then if you like change for something else, but don’t expect that this will stop you falling off…it is by falling off we learn how to stay upright.  A bit like military air crashes…it is always pilot error!

  37. @Nate

    I prefer something closer to 7 point oh V bar. I don’t think it was mentioned (I didn’t read very carefully) but the front tire gets about point V less bar than the rear.

    I ride the same pressure front and back. In fact, I don’t know why people ride the front lower. The front tire has less weight on it and isn’t used for traction; you just need enough for steering ans some suspension. With less weight on it, it will be less susceptible to loss in rolling efficiency.

  38. @Batman i’m a firm believer in the conti gatorskins.  i’m 88kg, 193cm tall, & ALWAYS ride them at 110.  i’ve never had a pinch flat (of course, having said that, i’ll get one on my next ride) in the 4 sets i’ve had.  the trick on installing new ones is that once you get it on the rim, pump it up to a very low 20-30psi.  then hold the wheel up so you can look along the bead as it spins away from you, spin it in your hand & eyeball the bead/little groove as it spins away from you.  it should maintain the same distance on the edge of the rim as it turns.  if not, deflate & try again.  it may take a time or two, but this works for me.  when the little groove maintains the same distance from the rim on both sides, pump it to full pressure.  double-check your work, then ride.

  39. @frank

    @Nate

    I prefer something closer to 7 point oh V bar. I don’t think it was mentioned (I didn’t read very carefully) but the front tire gets about point V less bar than the rear.

    I ride the same pressure front and back. In fact, I don’t know why people ride the front lower. The front tire has less weight on it and isn’t used for traction; you just need enough for steering ans some suspension. With less weight on it, it will be less susceptible to loss in rolling efficiency.

    Because it’s what the pros do.  It’s not for us to question, but to follow, just as we wear our sunnies with the earpieces outside the straps.

    In all seriousness, it suits the roads I ride — and I will posit that the velominutus should carefully weigh several factors in reaching optimum tire pressure:  chiefly, the tires chosen; the weight of himself and machine; the terrain to be covered; the quality of the roads; and the weather. There is also the deeply subjective matter of tire pressure philosophy: is more pressure more, or is less pressure more?  Early in my travels I subscribed to the latter philosophy.  The bike felt fast on smooth pavement but I found myself avoiding rough roads and was chickenshit descending on poor surfaces.

    I have now learned that to attack the rough sectors (which are prevalent around here) and carve the descents on these same roads with the grace of a skier, partly because I have better bikes, but also because I believe in running my tires at considerably lower pressures.  Because there is less weight on the front, it can be run softer, improving ride and grip on the rough stuff.  You think front wheel traction doesn’t matter.  This is true up until the point it does and the front washes out in some gravel at the apex.  Not fun!

  40. My previous tires were Gatorskins. Very tough and durable. I can’t remember how many miles I got out of them, but it was a lot. Very few flats, and those were my fault for hitting potholes, etc. Good tires, I thought.

    But 4000s’s feel so much better to me in turns that I’ll sacrifice a bit of money and time. I did experiment with different pressures in the Gatorskins, but they were never going to feel any better than they did. Turn entrances felt really sudden, and it wasn’t all that great after I’d entered my line. On the 4000s’s, the transition is smooth and predictable, and it’s easier to relax and hold my line all the way through the turn.

    I used to, and occasionally still do, ride an older “sport bike”–i.e., motorcycle–with good rubber on it, and the 4000s’s come way closer to giving me that feeling of smoothly carving a turn on two wheels. If I were commuting, I’d stick with the Gatorskins and be happy as a clam.

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