[Closed] Optimum pressure on 35mm gravel tyre may be lower than you think...

That’s interesting! Also explains why my 40psi tubeless G-Ones don’t feel that much slower than my 100psi road bike 😄

Very interesting!

I suppose the principle applies to mtb tyres to some degree or another too?

Yes - but suspension  on MTBs changes the picture slightly as the forks and shock handle much of the upward wheel travel - the thing that's effectively slowing you down.

Ah yes, good point.

💡 But what's the optimum pressure to avoid rim dings? It's all a balance / compromise according to terrain & riding style. The 3 Peaks is always gonna demand 60+psi.

3 peaks is not a gravel ride. And as they said, keeping.riding at almost any tyre pressure > stoping to fix a puncture.

qwerty

But what’s the optimum pressure to avoid rim dings?...

Good question. In the old days before we had pressure gauges we used to look for about 20% deflection when sat on the bike. It's a useful guide even now although tyres re much better and more compliant.

However we were always told to pump up our tyres as hard as possible - it wasn't easy on the old pumps getting any high pressure. It's a habit I had to unlearn after I got a fatbike, and since then I have been progressively dropping the pressures on my skinny tyres.

Previously I would have put 80psi in a 35mm. At the moment I'm using about 40psi which was good enough for me to ride the Orrin Dam part of the HT550 without a pinch flat on my shopping bike.

It's definitely worth experimenting to find what's best for you.

Schwalbe G-One 40-622 on a Ridley X-Trail here. After a bit of faffing, I've settled at 50psi on the road and 30/35 (F/R) on the gravel and this seems to be a good balance of comfort and speed. In fact, I remain astonished by how well the tyres roll at 30psi on the road!

I'm quite a sturdy chap (85kg), but ride quite lightly so have a good track record of not trashing rims.

Interesting. It's what I found too...running 40mm wtb nano's on my cdf commuter (tubeless). Used to have them around 40psi for the commute thinking they would roll faster.

Now run 27/30 psi (f/r)... Ride is so much smoother. Less fatigue and strava tells me around a whole two mins faster on average over 11 miles. Braking performance improved too (assume as contact with road is increased).

Definately a sweet spot though as any lower I can feel a bit of squirm and would risk damage to rim. Also could see tell tale sign of bead pulling away from the seat on hard cornering (sealant blow through) which is not good!

@epicyclo - the Erchless Forest to Orrin Dam track is a good test as it's quite a varied surface. I remember your ride report about doing it on the Pompino.

I think the take-away is that you need to test your own setup in a similar manner to their rolling test. I run my WTB Riddler 37c at about 40psi front/45psi rear but that's mainly road and it feels a bit skittish off-road on Dales tracks.

good read. Using no science and unreliable feelings based testing I came to the conclusion that around 35psi is a good pressure for my 35mm gravel kings. The highest pressure I tried was 50 and it didn't feel any quicker on road and definitely harsher on gravel / bridleways.

I would like to see this kind of research and instrumentation used to measure 'vertical compliance' in rigid bike frames and see if its really a thing or just magical thinking.

Schwalbe G-One 40-622 on a Ridley X-Trail here. After a bit of faffing, I’ve settled at 50psi on the road and 30/35 (F/R) on the gravel and this seems to be a good balance of comfort and speed. In fact, I remain astonished by how well the tyres roll at 30psi on the road!

Interesting, is that tubed or tubeless?

Pinch flats would become an issue at 30psi offroad I would imagine. Although I used about 25-30 psi in a recent cross race where I knew no rocky sections would occur. Normal mixed riding I use about 40-45psi with 38mm G one allrounds and tubes. If I was riding just gravel roads I suspect pinch punctures would be less of a problem.

Roll down tests are hardly scientific though. Two different riders on two different bikes, the rear one riding twenty feet of track different to the front rider, each giving their own half pedal stroke to start (at what power?).

Interesting, is that tubed or tubeless?

Tubeless. Don't think I'd run that low with tubes.

Roll down tests are hardly scientific though. Two different riders on two different bikes, the rear one riding twenty feet of track different to the front rider, each giving their own half pedal stroke to start (at what power?).

But the second bike consistently used the same track as did the first.  The only difference between tests was the tyre pressure of the front bike.  It was the difference between the time differences that provided the interesting comparison, so slight differences between the two tracks and riders would cancel out.

https://janheine.wordpress.com/2016/03/09/tire-pressure-take-home/

I've just switched from tubeless G-Ones to Specialized Roubaix 2-bliss and the Speshes are definitely better run at lower pressures. After reading that might try them a tad lower too (about 50psi, I reckon). Not much gravel, but all the roads I commute on are pretty rough.

I pinch puncture for fun on my cross bike, so am stuck at least 55psi (about as low as I can go with out pinch puncturing) & I have tried setting up my tyres as ghetto tubeless but no luck unfortunately.

I wish everyone would mention their internal rim width when commenting. I've got Soma Cazaderos 40c, and they feel squirmy, pretty awful at 30psi on 19mm internal, but run fine at that pressure on 22mm internal rims.

I wish everyone would mention their internal rim width when commenting. I’ve got Soma Cazaderos 40c, and they feel squirmy, pretty awful at 30psi on 19mm internal, but run fine at that pressure on 22mm internal rims.

My 40c G-Ones are on 25mm external width rims and are fine at 30psi.

Mine are 19mm with the nano's tubeless. Fine for me tubeless at 27/30psi mix of road and single track (plus blue/red swinley)

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