Rolling tyre sideways on landing
Discussion
I've a niggly problem with my new bike. If I land a jump slightly off centre (ie veering a little to the left or right on the front wheel) the tyre has an annoying habit of rolling sideways on the rim - making balance all wrong and a crash really rather likely. I'm running a decent PSi, so it's not underinflation.
I'm wondering if this is as I'm used to rim brakes (maguras) and a wider width rim. With the advent of discs, are rims generally less wide than previously? This might explain why the tyre has a tendency to roll?
Also, I'm using tyres with (I think) a kevlar sidewall - which doesn't seem to be as rigid as previous ones. Can't recall what they are but they were standard fare on my Dale F4, possibly Vredesteins (Sp?). Is this a likely factor?
Bottom line is I need to learn to land my jumps straighter, but in the medium term I'd like to avoid veering off into the hedgerows when I get it a little out of shape.
Any advice would be welcomed.
I'm wondering if this is as I'm used to rim brakes (maguras) and a wider width rim. With the advent of discs, are rims generally less wide than previously? This might explain why the tyre has a tendency to roll?
Also, I'm using tyres with (I think) a kevlar sidewall - which doesn't seem to be as rigid as previous ones. Can't recall what they are but they were standard fare on my Dale F4, possibly Vredesteins (Sp?). Is this a likely factor?
Bottom line is I need to learn to land my jumps straighter, but in the medium term I'd like to avoid veering off into the hedgerows when I get it a little out of shape.
Any advice would be welcomed.
Kevlars are invariably sold as foldable tyres.
This obviously has an impact on their stiffness with regard to what you are mentioning as rolling upon landing.
Simply by buying normal tyres will reduce this, but also bear in mind that jumping tends to do this to skinnier tyres anyway, so you combination is probably the worst!
Hope that helps
This obviously has an impact on their stiffness with regard to what you are mentioning as rolling upon landing.
Simply by buying normal tyres will reduce this, but also bear in mind that jumping tends to do this to skinnier tyres anyway, so you combination is probably the worst!
Hope that helps
Kevlar beads won't make a lot of difference to the side wall of a sinlge ply tyre.
If you're running sufficient pressures then it sounds more like the width of the tyre is at the upper limits that the rim can take.
Although, poor landing technique will always cause a tyre to deflect and move around regardless of set-up.
If you're happy with the tyre tread and width then see if there is a dual ply or downhill version of it available and swap the rear out. The stronger side walls would help hold the tyre up. Alternatively, try fitting a downhill inner tube to the rear. Again the thicker tube should help hold up the tyre sidewall.
If you're running sufficient pressures then it sounds more like the width of the tyre is at the upper limits that the rim can take.
Although, poor landing technique will always cause a tyre to deflect and move around regardless of set-up.
If you're happy with the tyre tread and width then see if there is a dual ply or downhill version of it available and swap the rear out. The stronger side walls would help hold the tyre up. Alternatively, try fitting a downhill inner tube to the rear. Again the thicker tube should help hold up the tyre sidewall.
Edited by mk1fan on Friday 26th June 14:09
henrycrun said:
Not enough air ?
Was my first thought, but I'm running it well inflated as I figure bump absorbtion is what my headshok is for. Going to swap one of my old tyres off of my hack bike onto it on the weekend and see if it makes a difference. Its a little thing, but it's really winding me up!
May well be that the rim isn't really wide enough for the tyre - fine for normal riding, but not for really big hits.
If you're running, say, 2.3in tyres and landing decent jumps them I'd be running something like Mavic's EX729 rims (29mm width,tyre range 2.3-3.0in). Running the same tyre & PSI on, say, a Mavic XM819 (19mm width, tyre range 1.5-2.3in) you can expect it to roll a lot more.
Not that it really matters - if you're landing sufficiently big jumps often enough your wheelset won't last very long if you've got narrow rims.........
If you're running, say, 2.3in tyres and landing decent jumps them I'd be running something like Mavic's EX729 rims (29mm width,tyre range 2.3-3.0in). Running the same tyre & PSI on, say, a Mavic XM819 (19mm width, tyre range 1.5-2.3in) you can expect it to roll a lot more.
Not that it really matters - if you're landing sufficiently big jumps often enough your wheelset won't last very long if you've got narrow rims.........
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