You are hereForums / By Discipline / Mountain (off road) / MTB Gear / Tubeless pressures?
Tubeless pressures?
Thanks to all who helped with their advice on setting up tubeless tyres. It worked out great and I love how well the tyres roll and grip.
I'm just wondering what your thoughts would be regarding an appropriate pressure for 2.1" rubber around the Dam, and around Ourimbah at the Fat Tyre.
I realise there's a bit of trial and error involved, and a bit depends on how I ride, so I'm just looking for a ball-park. I'm roughly 85kg kitted up + ~13kg bike, if that helps.
Thanks (again) for your help.
- Login to post comments
- Bookmark & share
Tags
Hey Hawkeye,
A few ideas...
Mavic rims need a higher 'minimum' pressure to stop 'burping' even with UST tyres.
Stans Rims hold the air better, and you can go 3-4psi lower even with non-ust tyres.
The limiting factor is tyre stability on the rim, burping, and at a very low pressure the rolling resistance starts to go up.
For your weight I recommend 34 rear, 32 front for all round riding including the dam.
If you feel the tyre moving around on the rim (sideways flex) go up in 2 psi steps.
I had a lot of tyre burping and movement - even rolling off the rim early on and even considered going back to the old rims. Wasn't running any real low pressures either - what I found helped was pumping up to around 50 psi and riding around the road a bit and then going back to lower pressures. Working a treat now I'm 90+ kg's kitted up and run 34 front and 36 rear
Thanks for your responses.
Hmm - I'm a bit confused now.
The pressures you nominate are 2-4psi higher than what I was running *with* tubes on mavic XM117 rims,which was 30 on the front and 32 rear.
The tubeless setup is Mavic Crossland rims mounted with foldable 2.1 Ignitors on front and 2.0 Larsens or 2.1 Crossmark eXCeptions on the rear, depending on conditions. Bike is a Jekyll.
I hate getting punctures, especially during a race so I run 38 - 40psi (front and back)... that's with Crossmax SL wheels and CrossMark 2.1 UST tyres on a Rush.
I ride predominantly XC (when on a MTB bike), with the Dam being a local training ground... I'm also a fair few kilo's lighter than you...
Junkie, actually like you I run 38-40psi on UST's as a carry over from my non-UST days because "I hate getting punctures".
I was only discussing the advantages/disavantages of running high PSI on UST last weekend and paid particular attention to the feedback I was getting through the tires at high psi and with a stiff suspension - it was very noticable. I am now going to drop to mid to low 30's to see if the tire absords a lot of the feedback without compromising rolling resistance.
4 years ago, I'd often pinch flat if my rear was under 38psi.
Never pinch flatted on the front, but still ran about 34psi.
It might come down to personal preference, but I find myself, that 32-33 on the front and 33-35 on the back works well for me. This is with Stans olympic rims, crossmarks, larsons, small block 8s, & nevegals. At the scott24 I ran 30 on the front for more grip as it was really sketchy in places.
I also have Stans Arch rims which are a couple of mm wider, and I can run 2 psi lower.
I've got some stans freeride rims at 28mm wide, and can go 28 front and rear with the same feel.
I did some rolling resistance tests one day, trying pressures at 2psi increments over a ~200m gradual downhill section that flattens out, and found that between 28 and 40psi the difference in rolling distance was no more than 5m over about 20 runs. Higher pressure felt like it was rolling faster, but the best distance was at 34/36
I was really surprised that it was so close at the lower pressures. They say that the tyres conform to the micro-obstacles like stones and small bumps better at low pressures, and even though it doesn't seem so fast, it is really close.
I had a long chat with Craig Gordon one day, and he said that for his weight (on Crossmarks) he likes around 31/33 but if the course is fast with open sections he likes it a bit harder. He tends to favour a lower front pressure so he can get the front to bite when it slides "more than he expects".
I run 30 - 32 front and 32 rear. Currently with UST Nevegal front and Small block 8 rear on crossmax ST's. I weigh at least 95kg kitted up but am not an overly agressive rider. Never had a puncture or burping. Used to run 2.35 UST Ignitors on 819 rims at the same pressures, again, no punctures or burping.
What do you reckon..... hexed myself for the Fling hmmm ?
CB