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  1. #1
    Join Date
    Feb 2006
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    18

    700c -> 650c on a Road Bike

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    Hi everyone, I've just bought a very small road bike frame and had it fitted with standard parts to get me going. However when I saw the 700c wheels on it it's definitely all out of proportion. I'm worried that I might have a bit of toe overlap and would like to put some 650c wheels on it instead. Does this mean that I will have to change the fork as well? Or are there brake levers that will be able to reach it that extra bit further. Also I have the 170mm cranks and have heard horror stories of pedals scraping the ground when using smaller wheels. Fact or Wivestale? Thanks a lot!

  2. #2
    Join Date
    Aug 2003
    Location
    Bendemonium
    Posts
    9,684
    Why did you buy this bike if you don't like 700 wheels? Frames and fork are designed to be ridden with certain wheel size. Brakes won't fit, fork rake will be wrong, BB god only knows, I'm not an engineer. I've never heard of any adaptors to make brakes work.

    I don't think I have one bike that doesn't have toe overlap. I've never had a problem, you just need to be aware of it. Didn't you determine overlap before you bought the bike?
    Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.

  3. #3
    Join Date
    Feb 2005
    Location
    Far from home
    Posts
    373
    Quote Originally Posted by JoHunter
    However when I saw the 700c wheels on it it's definitely all out of proportion.
    Forget how it looks, does it function?

  4. #4
    Join Date
    Apr 2005
    Location
    Vancouver, BC
    Posts
    3,936
    Quote Originally Posted by JoHunter
    However when I saw the 700c wheels on it it's definitely all out of proportion.
    What do you mean by "out of proportion"???

    I have a very tiny frame and the wheels _do_ look very big on it. It _looks_ out of proportion, but it's correctly sized anyway.

    I think you should be a bike fit with a professional at a reputable bike shop. But it is certain that your current fork, if it is made for 700 wheels, will not take 650 wheels.

  5. #5
    Join Date
    Oct 2005
    Posts
    2,309
    I have a size 44 Specialized w/ 700's on it and it rides fine. I don't know what you mean by "toe overlap" but I've never noticed a problem. I guess when I look closer at my bike I can see how the wheels look bigger, but it doesn't bother me. Though My new tri bike will prolly have 650's on it as thats what the smaller frame sizes come with.

  6. #6
    Join Date
    Oct 2005
    Location
    Christchurch, NZ
    Posts
    357
    You say you are worried about toe overlap - but have you actually checked if it is an issue. I'm 5'1" and yeah both road bikes I've had look out of proportion - not wanting to offend anybody but I refer to them as mutant dwarf bikes - but I think that is part of their charm. I haven't had a problem with toe overlap.

  7. #7
    Join Date
    Feb 2006
    Posts
    18
    Hi everyone thanks for the replies. I was unable to judge the toe overlap on this bike prior because it is a custom made frame (not for me, a second hand one I found in my size). My LBS was willing to fit it with standard parts. I wasn't sure if the fork of the bike was to accomodate 700c or 650c wheels. Now that I actually have it with the 700cs there is a bit of overlap. Depending how I turn it my toes clip the front wheel, so I have to be a bit careful with it. I may end up getting shorter cranks that might help. From various different sources I found that a lot of people recommended the 650c wheels for shorter people to help with acceleration and climbing hills. I have heard of people turning their road bikes into tri-bikes and wondered if they bought new forks or found long-reach brakes.

    Actually thinking it about it now, it is very odd that a custom built frame would have the toe overlap problem. I would think most small frames that were made to accomodate larger wheels would make the effort to avoid it.
    Last edited by JoHunter; 02-07-2006 at 02:24 PM.

  8. #8
    Join Date
    Feb 2005
    Location
    Far from home
    Posts
    373
    I was doing some investigating re: crank length yesterday. I learned that a longer crank length allows for better leverage but dictates a lower cadence. Better for power on an off-road machine. Shorter cranks allow a quicker cadence, better spin and don't require the knee to achieve as intense an angle (SAVE THE KNEES !)

    I also came across some calculations vis a vis crank length as a percentage of femur length. Can't find the link now, but the gist of it is that even 165s can be *too long* for a petite woman. But then there's the study Sheldon Brown links to regarding wattages produced using different crank lenths (from 120-220 I believe) with the greatest wattages being produced using the mid-range cranks.So much information, is that smoke coming out of my ears.... ?

    Anyhoo, I'm 5'3", 27" inseam, on a custom frame with 165 cranks. Have 165s on all my bikes and feel loss of power and sad knees on anything longer. Shorter cranks might benefit you in many ways, including eliminating the overlap issue.

  9. #9
    Join Date
    Aug 2003
    Location
    Bendemonium
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    9,684
    Quote Originally Posted by JoHunter
    Depending how I turn it my toes clip the front wheel, so I have to be a bit careful with it.
    Is this when you are riding or when you are standing in the parking lot with one foot clipped in?
    Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.

  10. #10
    Join Date
    Sep 2001
    Location
    Lakewood, Co
    Posts
    1,068
    Quote Originally Posted by JoHunter
    Hi everyone thanks for the replies. I was unable to judge the toe overlap on this bike prior because it is a custom made frame (not for me, a second hand one I found in my size). My LBS was willing to fit it with standard parts. I wasn't sure if the fork of the bike was to accomodate 700c or 650c wheels. Now that I actually have it with the 700cs there is a bit of overlap. Depending how I turn it my toes clip the front wheel, so I have to be a bit careful with it. I may end up getting shorter cranks that might help. From various different sources I found that a lot of people recommended the 650c wheels for shorter people to help with acceleration and climbing hills. I have heard of people turning their road bikes into tri-bikes and wondered if they bought new forks or found long-reach brakes.

    Actually thinking it about it now, it is very odd that a custom built frame would have the toe overlap problem. I would think most small frames that were made to accomodate larger wheels would make the effort to avoid it.

    It's not so odd having toe overlap on a small frame with 700c wheels. It depends on who made the frame and what material it is. I'm planning on building a custom frame and I was working with a well known company that does custom build. I'm looking at a ti or ti/carbon combination. The frame I wanted is only available with 700c wheels because the company doesn't make a carbon or ti rear triangle small enough for 650c wheels. So I would have a 44cm frame on 700c wheels plus the spot where the tt and rear triangle meet wouldn't match up. Also, I would have 1cm of toe overlap.

    Since there are other companies that can do small frames with 650's I nixed this design.

  11. #11
    Join Date
    Feb 2006
    Posts
    18
    fixedgeargirl: Thanks for the information, I've read a few articles that agree with you on crank length and have found a place that will sell me the shorter 165mm cranks. I'm hoping this might help my legs as well as help avoid the overlap problem.

  12. #12
    Join Date
    Feb 2006
    Location
    los angeles, ca
    Posts
    3
    Hi JoHunter,
    The toe clip overlap problem can be pretty bad on smaller frame bikes. I test rode a 47cm WSD Trek, a 48cm men's Cannondale, and a 47cm Bianchi Eros Donna, all with 700c tires and 170 cranks, and I found the overlap problem significant, significant enough to make me want to avoid it at all costs. Like you, I began to research the idea of retrofitting 650c wheel/tire combos, but was told that the brake setup would not work with the smaller wheels.

    I'm 5' 4" and I have a shorter torso, and hence a bit of a reach problem. I need an effective top tube distance of 19.5-19.7 inches.

    Eventually I began to research the possibility of a custom-built road bike, and became a regular visitor to the sites of Luna Cycles, Waterford, even Litespeed! Unfortunately, all of these great products were out of my reach money-wise. I'm a cycling newbie, and while I am wildly enthusiastic, some might say even obsessed, with the sport, I could not justify spending 3K plus on a new toy.

    Finally, I stumbled upon the site for Rodriguez Cycles in Seattle. They make custom bikes for the hard-to-fit. They use 650c wheels on their smaller frames, and in addition, the women's road design has a more relaxed geometry than is typical - the top tube is sloping, the head tube is longer. I ended up ordering a custom bike from them, steel frame, 650c wheels, 165 cranks, and Campy setup for a little over 2K.

    I received the bike this afternoon (waited by window all day for brown UPS van to appear), and I must say, it looks great! Because of all the rain in L.A. today, I was only able to ride it slowly, in circles, around our underground parking. Even with all the customization, there is still a bit of an overlap problem when I clip in to the pedals, but it is far less than it was with the other 700c/170 crank bikes. From my viewpoint in the saddle, it looks like 1cm of overlap, but that's a guess.

    So in closing (I know, long post), I would like to say that I do not think that the toeclip-overlap problem can be entirely eradicated in a small-framed road bike design. If you talk to a builder, they'll sketch you a diagram of the bike, and show you the wheelbase and the angles that work, and then I think you just have to decide what you can live with. But smaller wheels and cranks do minimize the problem.

    Good Luck with your search!

    JCL

  13. #13
    Join Date
    Dec 2005
    Location
    WA State
    Posts
    4,391
    I have a Fuji 44cm frame with 700's and 165 cranks. I've been informed by various sources that the setup shouldn't work at all and that the angles are all weird to accomdate the larger wheels, but it fits me to a tee. I'm short with shorter torso and arms than legs. I used to have a bigger bike and can stand over a taller frame, but I really need the shorter top tube. I have no overlap problems at all- I do have small feet - size 4.5 road shoes. As far as the crank length goes - longer ones would mess up my knee position which is pretty darn perfect now, so even if it wouldn't cause overlap I wouldn't want to change it.

    I haven't ever had a bike with 650's so I can't say that I know what the difference would be like. I've heard that smaller wheels climb better, but you end up having to spin faster to keep up on the flats. I've also heard that you can compensate with the gearing. I would love to take one for a test spin someday just to see which feels better to me.
    "Sharing the road means getting along, not getting ahead" - 1994 Washington State Driver's Guide

    visit my flickr stream http://flic.kr/ps/MMu5N

  14. #14
    Join Date
    Sep 2004
    Location
    Charlotte, NC
    Posts
    508
    Toe overlap is a hugely overrated problem. It only occurs when you turn the wheel a significant amount. When actually riding, one turns the wheel very little and uses a shift in weight to take a turn. Shoe size does affect the degree of toe overlap.
    As for crank arm length, there are a lot of formulas out there. The one I see repeated the most is inseam (with shoes on) in cm x 2.14 = crank arm length in mm. Here are some websites:
    http://www.nettally.com/palmk/crimplic.html
    www.sheldonbrown.com/cranks.htm
    and so many more...

  15. #15
    Join Date
    Feb 2006
    Location
    los angeles, ca
    Posts
    3
    JoHunter,
    I forgot to mention that the Terry Bikes website has lots of good info on women's fit...
    http://www.terrybicycles.com/cycling_savvy/fit.html

 

 

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