different rims , front/rear, effect on general riding

nielsamd

Is there any perceived wisdom about having different rims on the front and back wheels? Obviously even wheelsets are often assymetric in that regard given they often have different numbers of spoke/nipple holes... but I am talking about semi-random varying of rims for general road use... not like the more extreme versions of rear disk wheels for time trials and pursuiting.... but just a deeper rear section rim with a shallow front rim... to get some aero/rouleur benefit without totally compromising cross wind steering or climbing.

I recall getting speed wobbles occasionally in the past if I had certain non-matching combos of tires.

The Mechanic

Can;t see any reason why there should be a problem but I am sure someone will be along in a mo with a scientific opinion.

eridani

Mismatched tyres could readily cause handling problems due to differences in traction and behaviour under side loads. For example if one tyre was significantly grippier in the wet than the other then the handling of the bike could change dramatically and take the rider by surprise. How mismatched rims could cause problems is beyond me. Obviously a wheel has to have sufficient lateral stiffness to avoid rubbing on the brake blocks, so even the bendiest lightweight wheel will have a fraction of a degree of deflection at maximum load. By their nature, wire spoked wheels have massive radial stiffness, to the point that any radial deformation is meaningless compared to the deformation of the tyre. The mechanical behaviour of any two random wheels should be close enough to be meaningless. The only possible problem I could foresee would be the obvious aerodynamic issues of very deep rims, but that's more an issue of the forces induced by side winds than anything else and shouldn't matter at all unless you're talking about very deep carbon rims.

nielsamd

Thanks. That was interesting and useful.

To take it a bit further, rhetorically, , I wonder if any tyre manufacturer makes identical treads for clinchers and tubulars, either accidently or purposely, so that you could... mix them, front/rear. Not as a rule....who would want to carry multiple spares all the time... but just when the mother of invention is faced with neccessity.

woody-som

I've mixed wheelsets before, 20 - 50mm rim depths, and different brands of tyre and not noticed any adverse effects. Why should different tyres make much difference, who replaces both tyres every time they cut 1 ?

cougie

Never heard of speed wobbles due to bike tyre mismatches ? Are you sure ?

nielsamd

cougie wrote:

Never heard of speed wobbles due to bike tyre mismatches ? Are you sure ?

Well, it was a few years ago, but that was the only empirical evidence I could come up with at the time....... and have tried to have identical or similar treads ever since with no wobbles.

John.T

I just run what ever is spare in the garage at the time for my winter bike. Currently Conti 4 Seasons front and Rubino Pro rear. No trouble at all and I think it would show more on mucky winter roads if there was. Have also mixed rims many times with no problem.