what if i had a bike where the rear wheel is larger than the front wheel and vice versa?

Question

is this bike any safer or more dangerous?
does the slant cause any undue stress on the body?
are there any benefits at all?

Answer 1

If you saw the designs of a very old old bike "penny farthing" this is what it was - huge front wheel, tiny back wheel. Somehow this design was replaced with contemporary desing, I'm sure the change was for a reason.

I'm sure you've also seen monocycles - bike with one wheel. This has one additional degree of freedom - you can always fall forward or backwards. Same deal with the smaller wheel: your center of mass is too close to the same vertical axis as the big wheel, so you are always in danger of flipping over forward (if the mall wheel is in the back) or backward (if the small wheel is in the front) . If you manage to avoid this by design of the frame then it is probably fine. Another trouble is - smaller wheel is more "sensitive" to the roughness of the road.

Answer 2

You haven't mentioned what type of bike it is, or whether the different wheel size is by design or you're using a wheel other than what the bike was designed for.

If you're fitting wheels other than the design size, you may have issues with caliper brakes (can't reach the rims), and if it's the rear then a smaller wheel effectively lowers your gearing. Significantly smaller wheels will reduce ground clearance for pedals and chainrings.

Smaller wheels produce less of the gyroscopic effect that keeps a bicycle stable, but if you're only talking about small changes in wheel size you won't notice this. I'm no physicist, but I believe that if the frame ends up on a slant it's not designed for your steering angle will change, and this will affect handling. I'd expect forward tilt to make the bike more twitchy, backward tilt to make it less easy to change direction. You may be able to influence this by having a frame builder bend or replace your front fork.

Your riding position is determined by the relative positions and angles of saddle, handlebars and cranks - if you can still get the seat and bars where you want them then the wheel size is irrelevant. If you can't get them where you want them then expect your body to complain.

Answer 3

Usually, modern bikes with different tire sizes are configured small tire in front. Terry brand bicycles, some track or time trial bikes and some recumbent bike designs are just so. You gain some negligible aero advantage and conceptually lower wheel weight but for the most part it is not a practical design as you would have to carry 2 different size spares and the smaller front wheel size is usually a weird size that is not readily available in a bike shop. Terry uses the small front wheel to dial in women-specific geometries to which some women swear by.

The only safety concerns are that the smaller wheel size has less gyroscopic effect (less stable) so it theoretically is more prone to high speed wobble. It also has less rim mass to dissipate brake heat so brakes may overheat in downhills faster leading to less braking power.

Answer 4

a bigger diameter wheel is far less disturbed by making use of bumps. additionally, the bigger diameter generated extra gyroscopic tension for extra useful stability. on the time stability became extra significant than "flickablity" by using fact frames have been much less inflexible, and a "activity" type (consisting of a CB-F) became a strategies much less radical than what we evaluate a activity motorcycle now. In 1981, Honda widened the front and rear rims on the 750F for extra useful overall performance. in recent times, the rear tire on those motorcycles is type of the comparable width by using fact the front tire on a modern activity motorcycle!

Answer 5

Unless it is one of those rare bikes that is designed to have "mismatched" wheel sizes for one reason or another, you could be inviting handling problems. That is not a good thing.

Answer 6

The bike would be more dangerous as the centre of balance will be out of sync thus making you more prone to "flying" forward or skidding at high speeds on wet roads.

Body stress = after the accident

Answer 7

thats bad