Rear wheel "flex" or tyre

[Simmer]

I've noticed a few times now when putting some real effort in (eg standing to power up a ramp) or catching a pot hole a bit funny at speed, that the back wheel seems to go a bit "wobbly" for a few seconds. Almost feels like you got a flat, or the wheel just buckled.

I'm using shimano r500's with 25mm lugano tyres. The wheels are still in true with no signs of buckling and the spoke tension while not excessively stiff seems even.. I took the tyres off the stock wheels that came with the bike and replaced the gatorskins I had on them previously.

I've never noticed the problem before, so I'm wondering if its the tyres rolling out the groove on the wheel then popping back in ? Looks like they are folding rather than wired like the gators.

Has anyone else experienced this ? Am I on the right track thinking it's the tyres, or could it be the wheel flexing and truing itself ? (I'm 15stone and like I said above it only happens when i'm really pushing hard).

Cheers
Simmer

 

[ColinJ]

It could be that your bike frame is not stiff enough to withstand your effort? I can feel my steel-framed Basso bend when I give it some stick, and can get the chain to rub the cage of the front mech. My ultra-stiff aluminium Cannondale does not do it.

 

[Simmer]

Hadn't thought of the frame, it's the Marin Argenta A6 which has the same frame as their £1k setup. Think I'll go back to standard fit and take it from there... Stock wheels with the luganos, then try the 500's with the gators. If they all do the same I'll speak to lbs about it .

Cheers
Si