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Hi all , have gone tubeless due to in constant rear pinch punctures . I've also bought a digital pressure gauge as I didn't trust my floor pump. Anyhow , after much swearing etc tyres are on and pumped up. Wanted a Psi of around 27 front and rear. Pumped the tyres to what I thought was around 25psi, turns out it was 8,5. So,have pumped up tyres
to what the gauge says is 27 psi and I can't believe how hard they are. Are they supposed to be this hard?!?!
What makes you think your digital gauge is more accurate that your pump? Maybe they're both wrong?
It's a personal thing. The numbers are irrelevant. What matters is that you can experiment and more importantly, replicate your favourite settings.
But I've spent 20 quid on a digital gauge ...
Your digital gauge isn't reading bar, is it? 2.7 bar is about 39 psi so are you seeing 2.7, not 27?
It has option of both bar and psi . Just surprised how solid the tyre is at 27psi. I thought it would be a lot more malleable / soft
A big tyre with a tough carcass on a wide rim feels pretty solid at 27psi - comparable to a skinny lightweight XC tyre at closer to 40psi. There are a lot of dodgy pressure gauges out there though...
It's a Hans dampf 27.5 2.35 trailstar with snakeskin sw. Digital gauge is a sks air checker which gets decent reviews .
Sounds like we might know why you were getting those pinch flats! 😉
8.5 PSI must have felt like riding in sand!!
@ 27 PSI you should be able to squeeze them a bit, should not be rock hard
should not feel like they "ping" and bounce off a sharp bump like a root or kerb.
chiefgrooveguru - MemberSounds like we might know why you were getting those pinch flats!
+1 😆
Trust the guage I would say.
27psi in a 2.35 tyre will be quite hard. Roughly, according to stan, this will suit a 13.5 stone rider. (Weight in lb / 7 = tyre psi). Fwiw, I think the stans guide gives slightly too high pressures, but obviously it varies per individual.
8.5 psi is fatbike territory!
I run Hans Dampfs on my full suspension tubeless 20 psi F, 22 R. (2.35 26" snakeskin Trailstar on relatively narrow rims) I weigh 175 lbs.
Inflate until there is a small amount of sidewall deflection when you bounce on the pedals. Thats a good starting point, then work out which (if any) of the gauges you own are accurate 🙂
Ha yes it's does seem previous pinch flat mystery is solved
I'm 80kg, wheels are newly built ryde trace trail rims 25mm internal width so pretty wide. It's a full sus bike.
I'll reduce to around 20-22
I would hope that he gauge is accurate.... Reminds me of using a compass when you are lost .... I've gotta trust the compass...
I find it hard to fathom how someone could have been riding round on 8.5psi and not noticed it... Surely you'd notice your tyre was all over the place ? deformed ? didn't anyone else point it out ?
I would hope that he gauge is accurate.... Reminds me of using a compass when you are lost .... I've gotta trust the compass...
The gauge doesn't really need to be that accurate, just consistent
My thumb is the best pressure gauge I've come across for bicycle tyres 🙂
For cars and motorbikes I use a cheap - but accurate - RaceX RX0014
I'm 98kg and run around 30 psi on rear and about 28/27 on front with no issues.
weeksy - Member
I find it hard to fathom how someone could have been riding round on 8.5psi and not noticed it... Surely you'd notice your tyre was all over the place ? deformed ? didn't anyone else point it out ?
There is a little confusion with that . I wasn't riding around with 8.5psi. I pumped to what I thought was around 20psi when I got the new wheels/tyres , I.e much lower than I had been using because I thought tubeless would allow me to so that. I guess I was running with tubes, around 15 -18psi when I thought it was around 30psi. Confusion all round
27 PSI tubeless feels way harder than 27 PSI non-tubeless. Asked about this a while ago but never got a satisfactory answer.
I've run my HDs on 26" wheels at 9 and 10 PSI with no problems.
I'm 64kg wringing wet though!
I still run tubes, so I do the kerb test. Inflate the tyre, then press it hard into the edge of a kerb, if it bottoms out then its still too soft.
No idea what pressure Im running at, but I tend to have a little more pressure in when its dry when traction isn't at a premium and I can roll a bit faster.
grum - Member
27 PSI tubeless feels way harder than 27 PSI non-tubeless. Asked about this a while ago but never got a satisfactory answer.
That's interesting to read. So if it feels harder, it is logically, harder... Therefore I should be able to run much lower pressure.
With tubes and the low pressures I was running I got a pinch puncture virtually every ride. But the grip was fantastic.... Grip but no punctures please !
Tubeless feels softer at 30psi than tubes for me
It's a personal thing. The numbers are irrelevant. What matters is that you can experiment and more importantly, replicate your favourite settings.
+1
I ride a 29er hard tail and I'm 85kg. I've one of those digital gauges too but it's more a reference thing. I've just rebuild my back wheel with some wide P35's rims running tubeless with a 2.25 Rocket Ron so I'm testing how low I can go without the tyre deforming and damaging the rim. At the beginning of each ride I let out 2psi and my digital gauge says it's now at 22 but I recon I've another few psi to loose before I start touching cloth on the rockiest trails around here.
There's a hard techy climb with 2 or 3 very large square edge rocks that I use as my 'test' ground. If I can clean that line without the tyre collapsing and deforming too much or the rim banging the rock then I know it's all good for everything else.
There's a hard techy climb with 2 or 3 very large square edge rocks that I use as my 'test' ground.
Sod the tyre pressures. How did you get the wife to let you build that in the garden?
Tubeless feels softer at 30psi than tubes for me
That's what I'd expect too! The tube rubbing against the inside of the tyre makes the carcass feel thicker and stiffer.
The main thing I notice with pressure is that a big reinforced tyre like my Trail King 2.2 Protection feels way harder (at the same pressure) than a skinny normal tyre like my XR-Mud 2.0 (the difference in size is much more than the 0.2" the claimed sizes suggest). And my Magic Mary Super Gravity 2.35 feels even harder thanks to the dual-ply sidewalls.
On my 6" full-sus I'm running 18-20psi in the Magic Mary up front and 24-26psi in the Trail King out back, (low when wet, high when dry). XR-Mud needs about 28psi in the mud and that wouldn't be anywhere near enough pressure to cope with rocky downhills.
A fat bike tyre at 9psi feels amazingly hard! Funnily enough although the thumb test is useless at detecting what the actual pressure is in the tyre if you use a variety of tyre sizes and types, it's pretty good at detecting what really matters - carcass deflection under load.
bigyinn - Member
I still run tubes, so I do the kerb test. Inflate the tyre, then press it hard into the edge of a kerb, if it bottoms out then its still too soft.
No idea what pressure Im running at
That's how I do my tyres also. Fool proof method I think.
Could be what you pumped to what you thought was 25psi had deflated a bit and reads 8.5 with the digital. Maybe it was really about 15 to 20.
When I first went tubeless I'd pumped up to 20, but sealant wasn't quite enough and it dropped to 10 when I rode. I hadn't checked at the time and just felt the ride was pretty awesome on the descents. Unfortunately the rim couldn't hold on (none tubeless Maxxis tyres on sealed tubeless rims). I now use about 3 cups of Stans and pump to 20 to 25. Have tried dropping them a bit, and feels better but then have had proper puncture that wouldn't seal when I did that. Not sure if that was more likely with lower pressure though. Do find I need more about 25 if it's a more pedally and climbing based ride.