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So went out tonight on the 'dale , and whilst not a crazy biker I do like to mess around a little . Anywho , whilst doing the smallest of jumps literally off grassy knolls etc nothing more than a foot max I felt my back tyre "twist" which was quite unnerving to say the least . I'm quite a lump at 15st , and I have 26psi in the back which I've been enjoying for comfort as much as anything . My tyres are conti race kings 2.2 . Do I need to be putting ore air in really ? I'm pretty sure it was th tyre twisting unless there is another underlying prob I've not noticed .
15st is quite a lot, and 26psi isn't. But yeah, you will get some tyre folding if you land a bit sideways or on a bit of a slope or an edge. It also depends on the rim / tyre combo. Unless it's causing you to lose control or burp air then I probably wouldn't worry about it.
Just be grateful you didn't bust the carcass - like I did a couple of weeks back doing pretty much the same...
40psi in the back tonight, 12.5 stone. A few trails but mostly just grinding out miles, some trail centre, a few natural trails. I'd probably drop it to 30ish on something properly technical
40 psi is proper hard and I'd have thought you'd lose traction on corners . I used to like high psi but for what it's worth its also nice to have a little comfort , and small bump absorption . I won't be going back up to high psi anytime soon .
Assuming tubeless?
If so then the usual formula would give a rear tyre pressure of 32psi. Try that and do the same jump and see what happens. If it's OK then work back down to your current pressure. Also are you sure that your pressure gauge is accurate? My track pump differs from my digital gauge by at least 10% - it will show 40psi whereas the digital gauge will indicate 35psi. Either could be wrong.
I'm having a few issues with my tubes tbh as I've got slime in them . Easy to pump. Up just not to let down ! Also reiks havoc with my digital gauge . My go back to normal tubes....
26psi is low for tubes, especially with those tyres. I'd bet the slime is whats stopped you noticing any pinch flats...
I have to run 40psi to prevent pinch flats when playing around (ie jumping). Tend to stick with 35-40psi now anyway (and I do ok in the corners 😉 ). Been using contis with tubes for over a decade and this has always been the case. I am switching to tubeless soon, promise 😕
I'm a 11st and I flat if I go much below 30.
I just my tyres before last night's ride and hadn't realised how flat they were . 20 psi rear 24 psi up front . So I banged 30 in either end , and went out . Very sketchy in comparison though obviously a bit quicker . Gonna come down 5 psi I reckon for a happy medium .
I've heard that a good starting point is your weight in Stone x 2 = min PSI. Works well for me, 22 psi on 30mm internal tubeless.