small frame sizing

[vqdriver]

i'm looking around for a bike for my wife, and had a question.

at what point is it better to have 650c wheels over 700?
i'm looking at sizing and frames as small as 45cm are still on 700c wheels. it looks ridiculous, like those low rider bikes where you're basically sitting in between the wheels. wouldn't it just make sense to design them around 650c wheels? in addition to the way it looks and marginally more difficult spinup (for those shorter legs on a 45 frame) toe overlap would be fairly extreme with the shorter wheelbase and not just a nuisance at stoplights.

aside from the lower availability of tires, i'm not sure of the advantage of putting 700 wheels on such small frames.

please enlighten.

[John M]

From what I have read, anyone under 5'3" or 5'4" should consider 650 and probably for sure under 5". My wife is 5'4" and has a 50cm road bike with the saddle pushed a bit forward on the rails and 60cm stem that we got several years ago before I knew much about bike fitting. It is OK, but definitely she could be fit better. She generally rides her MTB on the road with slicks because it seems to be balanced better for her. Possibly because of the accomodations that the smaller wheels allow in the frame build.

Toe overlap is not really the issue, but many brands build the really small for 700c with improperly steep seat angles or the top tubes are way too long. 650c/26" allows correcting both those problems with a well balanced bike.

[dwightskin]

Shorter than 5' 3" should consider 650C.

Some of the "big names" make nice small ladies frames. My wife has a 43cm trek that is great. Cannondale's smallest is 650C. Not sure if there are others.

I think the next size up was 47cm and was on 700C.

Also REI has one that is a "kids" bike that is on 26" rim (559) called the Novara Pulse.

In addition to toe overlap, the large wheels can mess up the steering by giving undesirable trail.

Basically only narrow road tires are available in 650C.


Dwight

[deechee]

Hi,

I'm 5'7" and absolutely love my 650c 51cm cervelo (51cm tt). Before I had it, I didn't mind the toe overlap on the Serotta road bike I own (52cm tt, 700c) but now that I don't deal with it, I really enjoy it. Cornering the 180degree turnarounds often found on tri courses is a breeze due to the smaller wheelbase, not to mention fitting it in the car behind the front seats is a breeze, even in our miniature '91 civic.

Yes, the tire selection stinks. Corsa Evos only come in 650x20, and 23's are available from Michelin Pro Race, Conti and some others but I haven't seen any 25's. Having used the tacx and Conti trainer tires on 700c, I really wish one would be available for 650c as well (but I don't think it exists.) I also find that some tire and rim compatibility really varies - sometimes extremely loose, other times really tight. That said, I'm very happy with my handbuilts. And geez, race wheels are easy to get for cheap.

I think geometry wise, it brings everything lower (bb, top tube for standover), rear triangle tighter and the fork doesn't have to a ridiculous rake (although for 650c forks available, there are only a handful). I'm comparing apples to oranges but holy crud the 650c ride on my cervelo is stiff. It was squirrely at first but I think that has more to do with the tri geo than the wheels themselves. I'm very comfortable on it now though. I know a number of our smaller riders on Giant and Cannondale 650c models and they love their bikes.

All this said, my 5'4" gf has ridden a 700c Giant TCR (Small, 53cm tt with a 7cm stem) ever since she started riding, and she's very happy with it. No toe overlap, and she's raced crits on it so there's no question about handling. She's not sure if she would really care for a 650c bike, but she also doesn't like sticking out ;)

[zap]

My wife Zip is around 5'2" and when she first rode her 650c one off csi (47cm c-c), she blew me away by how quickly she descended down some local twisties. I used to be able to snack at the bottom of that climb but she stuck right behind me.

Photo of her bike is posted here.

Our Serotta build sheet indicates a certain Dave Kirk as the geo meister.

Others I know really dig 650c too.

But I know of some were it turned out crap. One a custom ti job from some other builder and god knows what went wrong. Poor fit/odd geo?

I've spoken to several builders who do not offer 650c as to why they don't but ultimately got tired of the propaganda.

[RPS]

Yes, the tire selection stinks. Corsa Evos only come in 650x20, and 23's are available from Michelin Pro Race, Conti and some others but I haven't seen any 25's. Having used the tacx and Conti trainer tires on 700c, I really wish one would be available for 650c as well (but I don't think it exists.) I also find that some tire and rim compatibility really varies - sometimes extremely loose, other times really tight. That said, I'm very happy with my handbuilts. And geez, race wheels are easy to get for cheap.
If the bike is made to accept both 650C and 26-inch MTB rim sizes it can add a little flexibility in tire selection. With only brake pad adjustment it may be possible to go from skinny high-pressure road tires to much fatter road or trail tires.

[Hawker]

Hi,



All this said, my 5'4" gf has ridden a 700c Giant TCR (Small, 53cm tt with a 7cm stem) ever since she started riding, and she's very happy with it. No toe overlap, and she's raced crits on it so there's no question about handling. She's not sure if she would really care for a 650c bike, but she also doesn't like sticking out ;)


deechee,

I'm a 5'5" (almost) guy with a TCR but in the XS size frame. Even though your girlfriend likes the Small she might really like the XS if she tried it. Just a thought.

[steampunk]

i'm 5'3" average proportioned torso/arms and legs. my frame size sweet spot has been around a 48cm-ish ST, 51-52cm TT. everything i've ridden has been with 700c wheels, and the stock geo on my HSG IT in 48cm works very well. i have no toe overlap with the 52 rake fork and 170mm cranks.

on occasion i have borrowed a 650c Fuji road bike (my mom's, who is 5'0") as it had a triple and this was for a very hilly ride. the smaller wheels did feel more reactive and the bike felt very nimble (not twitchy though) under me. i thought it handled fine too, and later on just forgot i was not riding my own bike and a 650c one at that.

for my height i am probably right where both wheel sizes will work well on a properly designed bike. my advice would be to test ride both options if possible and let the overall feel decide.