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How Common Is Toe Rubbing? Deflection dangerous?(11 posts)

How Common Is Toe Rubbing? Deflection dangerous?jose_Tex_mex
Jun 29, 2002 6:58 AM
All,
My latest ride is a GT ZR1.0 with a Profile Design BSC Carbon fork (43mm rake). When turning the wheel more than about 15% in either direction the tire rubs my toes.

First question, how common is this? I understand with the new micro frames this is not unusual.

Second, how dangerous is this? I have done some calculations and determined that there will be no problems at speed (anything over 10 mph) since the angle of deflection (wheel vs frameset) is very small for most speeds encountered.

However, since stability and steerability are dependent on speed, the most likely time it will cause trouble is at low speeds.

Compared to my 5500 (longer top tube) I would need nearly a full centimeter, as measured linearly from crank center to axle center, in order to completely avoid toe rubbing. This would IMHO totally ruin the wheelbase and handling characteristics.

My cranks are 172.5. Does anyone really think that going to 170 (or smaller?) would help?

For now, I am content to "ride it out" the GT is a back up bike. But watcha think.

Thanks for any constructive feedback.
re: How Common Is Toe Rubbing? Deflection dangerous?Trent in WA
Jun 29, 2002 7:19 AM
In my experience with road bikes, toe overlap is very common and not dangerous at all. The only time you're likely to touch the front tire is when you're cranking slowly up a hill. You'll be applying power to the pedals, and your foot will touch the side of the tire, which won't cause it to come to a complete stop. When it happens, unless you're far more unlucky than I am, it'll startle you slightly, you'll go "Whoops!" (or you'll use a more colorful expletive), you'll correct for it, and then you'll keep grinding, grinding, grinding....

Don't worry about it. Of all the non-issues pertaining to bike fit, toe clip overlap is probably the biggest of the lot.

Trent
re: How Common Is Toe Rubbing? Deflection dangerous?koala
Jun 29, 2002 7:52 AM
It only bothers me when I try to trackstand and I get a little ragged at stoplights.
big feet...C-40
Jun 29, 2002 7:58 AM
Overlap is common if you have big feet and ride a small frame. It has nothing to do with the compact frame design. The only difference with a compact frame is a sloping top tube, shorter seat tube and seatstays. The front of the bike is the same. If you selected the proper frame size, the top tube length should be the same as a conventional frame. One of the disadvantages of compact frames is the limited size selection. Did you choose a frame with a shorter TT length than your conventional bike?

Changing cranks won't help unless the overlap is less than 1/8 inch.

You should seldom turn the wheels enough to cause the overlap, only during slow manuevering. Normal cornering is mostly done by leaning the bike, not turning the wheel (more than a few degrees).
Not too bigjose_Tex_mex
Jun 29, 2002 10:46 AM
Shoe size is nothing out of the ordinary. As for frame measurements the wheelbases are indeed different - my GT is shorter than the 5500. It does appear to have a shorter TT.

Thanks for the help. I am contemplating 165mm cranks.
not a big dealDaveG
Jun 29, 2002 11:35 AM
Don't do anything silly with your fit to try to avoid it. I've had overlap on a few of my bikes over the years (I do have big size 13 feet) and have never had it result in a crash or fall. Once you are aware of it any problems can be easily avoided.
i think i undertsand....Spirito
Jun 29, 2002 4:34 PM
if im correct you ride in NYC and its when in traffic and the stop start that it entails that it become's and issue.

i sometimes have a similar problem and as much as my retro head tells me to ride in clips and straps i use modern pedals and shoes as its just a lot easier.

i dont have any answers but do sympathize with you over your concern. them buses and taxi's are always too close for comfort and striking a toe on the wheel when trying to squeeze past always make the non-existant hairs on my head stand on end.

you should be OK but always excersize caution when on that bike at low speed in traffic.

ciao
There is such a thing as Too Much Toe Overlapjtolleson
Jun 30, 2002 3:39 PM
While it is true that due to TT length, headtube angle, and fork rake (and/or long feet), some bikes have toe overlap, and it is a non issue.

But there can be too much. Can you PEDAL the bike in a circle in a one-lane street? Can you pedal through a u-turn on the bike path? Can you safely turn the bike around without biffing during a slow steep uphill?

Some bikes are being sold and marketed to riders where they can't be manipulated in these ways, and I think that stinks. It is a tough call. The reluctance to use 650 cc wheels on bikes under 50 cm may be partly to blame.

Although toe overlap isn't unacceptable per se, when one has an inch or more it means toe contact through over 1/3 of a pedal stroke... I think that's unacceptable. The possibility of a minor bump with pedals at 9-3 o'clock is one thing... and inability to turn a bike around at low speed (a city riding issue, but also pulling out of aid stops, etc.) is another.
Track bikes suck for thisPODIUMBOUNDdotCA
Jun 30, 2002 5:54 PM
My track bike is horrible for this since the fork has almost no rake. But at speed it will never matter. However, it sucks cus at low speed trying to maneuver around when my feet are clipped in I either ruin my pretty shoes :( But thats with a fixed gear... on a road bike at speed worst case scenario you can ratchet the cranks.

So stay with 172.5... it simply does not make that much of a difference to buy shorter cranks that may rob you of power or just feel completely ackward.

Cheers,
Nick Corcoran
PodiumBound.ca
Err low speed ratchet the cranks!!! (nm)PODIUMBOUNDdotCA
Jun 30, 2002 5:55 PM
I should read before I post... sheesh!
All: Thanks for the feedbackjose_Tex_mex
Jun 30, 2002 6:26 PM
Thanks for all of the very helpful and constructive feedback. I have decided to "ride it out" and not go parts crazy.

As someone mentioned (Spirito?) I do often have to negotiate the traffic in NYC. I have rubbed once in traffic and once doing a near 90 degree turn. The concern is in traffic. True, you can easily ratchet. However, sometimes you just need a pedal stroke for stability no matter where the cranks are.

I imagine any problems will hurt my ego more than anything else.

Thanks again - hope to see some of you in Central Park or going to Nyack.