feel' slower perhaps, but they[ lowere pressure tyres] won't be - or at least there doesn't seem to be any evidence that they will be slower, more the opposite.

Are you trying to say that loer pressure tyres are faster than higher pressure tyres? This is counter to anything i have seen or read [ i acept you know more than me and are more current] so have you got any links as I thiought drag always increased as the pressure drops
I can accept it might be so marginal that for non racers its worth doign but

the prime function of suspension is maintaining 'grip' and comfort is largely a pleasant side effect

You sure it was not for comfort and grip was a pleasant side effect?

Other than provide a(nother) retail opportunity what does it do that a correctly sized and setup bike does not?

It gives you suspension on the bars - you may not want it [ neiother do i tbh] but its clearly over and beyond what the bike and frame alone offer

Steel CX frame and fork rider who uses the hoods *


* I have an eye disorder requiring contact lens and if i go on to the drops on this or my road bike i no longer look out my lens when i look up so i end up with a terrible neck position that no one can maintain for long.

You sure it was not for comfort and grip was a pleasant side effect?

Absolutely.



Road bikes have always relied on the performance angle as a marketing tool and peoples aspirations to be seen in that light. While I think (and you might too) that skinny steel frames, wide(ish) tyres / bars and long head-tubes look lovely, 90% of the road riding market probably think they look awful. I'm also including gravel under the broad heading of road here, based on a hunch that more gravel bikes are bought by road riders than are bought by mountainbike riders.

While many things in life that look right are right, there are those instances when they're not. Once you begin to appreciate how well something works do you begin to 'forgive' how it looks and on the back of that, maybe even start to appreciate the looks too ... see above about steel, wide bars, etc.

I'm off on one now, so I'll STFU and make a brew.

Are you trying to say that loer pressure tyres are faster than higher pressure tyres? This is counter to anything i have seen or read

Yes, they can be. Plenty of variables etc but a high pressure tyre is only fastest on a perfectly smooth velodrome. There's plenty of research, good and bad science, anecdotes and more on this topic, but the basic fact is that a lightweight or flexible-enough, usually larger, tyre at lower pressure can absorb imperfections in the road or track. A hard, high pressure tyre can't, it bounces off the bumps, it can't deform around them as easily. If a tyre bounces then it's moving the wheel axles and in turn the bike (assuming a rigid bike), and to some extent the rider, upwards. That takes energy to do so there has to be losses in forward momentum (conservation of energy, etc). That loss is generally greater than any losses in a light tyre sidewall flexing more at low pressure than at high pressure.

You can read more on this from Schwalbe's recent tests, on Jan Heine's blog, and Jeff Jones has always sold the reasons for big tyres and rims idea with his bikes as being about efficiency, not just grip and comfort. (edit to add, it was counter-intuitive to me first time I heard it too, I grew up thinking the narrow Bontrager modded MTB rims were cool and lighter was faster, then one day tried some 28mm tyres at 70psi i/o 23mm at 100 and found them to be faster than I expected)

The point to compare to the stem is that the tyre or a sus fork/frame copes with the bumps at the wheel level, the stem only very close to the rider contact point.

Fat bikes have been great for amplifying what James says above, it doesn't take to many extra psi in a fat bike tyre, before instead of the tyre deforming and going over the root or rock, you comically bounce off it and deflect.

'm off on one now, so I'll STFU and make a brew.

Carry on you are making sense

Personally I dont actually care much what my bikes look like- anyone who has seen them will agree.- i only care about how they ride. My interactions are limited to being on it and looking ahead or fixing it and how it look sis irrelevant to me. I realise aesthetics matter to most but i only care about how well it works - i think a lot of it is just marketting guff as very little of bike development is actually revolutionary - it is over a decade but not over a year ]

For example i use gravity droppers - ugly as but mine are over 10 years old and still going strong with only one servicein that ttime

Plenty of variables etc but a high pressure tyre is only fastest on a perfectly smooth velodrome

Makes sense and ta for the explanation. I should have relaised your point as my commute[ 18 miles each way] is 50/50 off road v road and my skinny tyred full road bike is no faster than my full steel mudguarded 35 mm CX bike with cross tyres on [ at least 4 kg heavier] - it murders it on the smotth road sections but anything bumpy and you have to go so slow to avoid buckles / serious discomfort/ be bounced sideways into a tree .

Cheers both

Just to add to that... The pro Peoloton (if the figures are to be believed)run at around 65 to 75psi with yhe higher pressure up the back end.

Normally the roadies (they really are an unusal bunch who think discs look wierd ) actually cant get their head round this and are just coming to thw point where they are (the non pro lot) are starting to experiment with thw wider 28c tirws and finding the benefits.

After reading the psi the pro guys use, ive gone for that setup (been using rpughly 28c for a while now)

Sorry.. (i didnt finish and just clicked submit)...

So adding to what James said and what you mentioned bout pressures... after going down to the 70s on my 28c (actually 25c but meaure up better/woder than a Conti 28c) I reckon I noticed a slight increase in speed and am constantly checking out different setups/parts to see what works best (80 miler commute means you need to try and be as efficient as poss).
Basically i just add enough pressure that i can't see the distortion of the tyre once sat on bike.

Lastly, regards wider tires being faster (which in a way translates to saying that lower pressures are faster as its only on a wider tyre you can get a lower pressure without problems... Kieth Bontrager said that many many years ago (I acrually read it in an issue of Privateer (mtb equicalent of Rouleur) which I read and at the time was slightly confused about... Smart man that lad and he's a gardener

I'll just leave this here... ;-)

https://www.ebay.co.uk/itm/Saddle-Suspe ... 0008.m2219

That saddle spring thing is scary.

That question about whether suspension is for grip (performance) or comfort is an interesting one. While performance may be the driver for development, the user need that’s being met in many cases is for comfort (hence Stu’s anecdote about people using their suspension to allow them to take it easy rather than eke more performance from their bike). Lots of people say they ride a full-sus because they’re old or have a bad back, etc.

Things get made and marketed for one reason and bought for a whole host of other (sometimes legitimate and sometimes misguided) reasons.

Flex stems may not make sense from a performance point of view but they may still meet someone’s particular needs.

redefined_cycles wrote:Sorry.. (i didnt finish and just clicked submit)...

So adding to what James said and what you mentioned bout pressures... after going down to the 70s on my 28c (actually 25c but meaure up better/woder than a Conti 28c) I reckon I noticed a slight increase in speed and am constantly checking out different setups/parts to see what works best (80 miler commute means you need to try and be as efficient as poss).
Basically i just add enough pressure that i can't see the distortion of the tyre once sat on bike.

Lastly, regards wider tires being faster (which in a way translates to saying that lower pressures are faster as its only on a wider tyre you can get a lower pressure without problems... Kieth Bontrager said that many many years ago (I acrually read it in an issue of Privateer (mtb equicalent of Rouleur) which I read and at the time was slightly confused about... Smart man that lad and he's a gardener

hi, i read this a while back and thought it might be of interest. https://janheine.wordpress.com/2019/01/ ... is-faster/

Edit: as you'll probably see there's a ton of stuff on there about tyre size, pressure etc. seems pretty impartial and pretty empirically based to me.