Shorties racing 650c vs 700c wheels?

[minan]

I'm one of those people for whom 650c wheels were actually made (4'9")

Are there other short people racing on 650c wheels who have also raced on 700c? I know I can only get into a true aero position with smaller wheels, but I'm currently racing with a 700c (Specialized ruby with clip-ons). I'm thinking of switching to a 650c road bike with clip-ons, or a 650c TT bike. If you have done this, can you let me know the advantages and disadvantages speed, efficiency, and aero-wise?

[Tri Girl]

We've talked about this here before (although I can't remember where ), but it's quite a debatable topic. I'm 6 inches taller than you and have raced on 700's and 650's. I'm now racing on my TT bike on 650's and I LOVE them far more than my 700's. For me, acceleration was MUCH faster on the smaller tire, and I feel like I'm much more proportionate on my smaller bike and wheels (aero and speed wise). Some people will argue that you have to pedal more with the smaller wheels, but it has not affected me one bit. Maybe I pedal a little more, but the power I can generate far outweighs the little more spin my legs have to do (and they can use all the spin they can get).
My advice is to go with the 650's. Just my $.02

[Eden]

I have bikes with both 650's and 700's. My road race bike has 700's, my tt bike 650's, my winter bike 650's. My advice - forget about the wheel size and first and foremost find a bike that fits you well. My experience has been the opposite of Tri Girls. My 700c wheel bike fits me the best and I am fastest on it, though I am closer to your size - I am 5' even. My winter bike is no slouch - its a nice light ti frame and try as I might, the geometry is just that little bit different than my race bike and I cannot produce as much power on it. (I'm the longer legged, shorter torso'd variety of short person )

As you've noted getting a good tt position isn't really possible for us shorties on bigger wheels, so yes my tt bike has 650's on it, even at that I don't have a lot of saddle to handlebar drop.

As far as having to spin more on a bike with 650's - its all about gear ratios. If you take into consideration your wheel size when you set up your gearing you don't have to have any different gearing than anyone else and you won't necessarily be spinning your legs in any crazy fast way.

[smilingcat]

If your top gear was 53 chain ring and 12 cog on 700C, then equivalent or very close would be 53 chain ring and 11 cog on for 650C. less than 1.3% difference in your candence to go the same speed.

And yes 650C is supposed to allow you for a faster acceleration over 700C. Otherwise there really isn't much difference between the two. Like Eden says, goe with a frame that fits you then worry about the wheel size. I've ridden both 650 and 700's

And remember too that you have less selection for wheels and fork for your bike with 650C. Same with tires. Years ago I wanted Velomax Accent wheel but they didn't make them for the 650C. They still don't. Velomax is now owned by Easton is/was it??

Smilingcat

[Tri Girl]

Yeah, the tire selection is definitely more limited in a 650. I'm glad I like my Vittorias, since they're about the only tire my LBS carries (not that I can only buy from him, but I like his discount he gives me).

[minan]

I wonder if there are any research studies with the same cyclist using both 650c and 700c in a time trial and/or road race course. The pros of 650c seems to boil down to these following things:

Pros
1. Possibility of a better fit for some people (e.g. better road or aero position)
2. Faster spin-up / acceleration
3. Lighter weight (easier climbs)
4. Slightly more aero (but counterbalanced by #2 in Cons)

Cons
1. Limited selection of wheels, tires, and tubes
2. Higher rolling resistance (because of bigger contact patch)
3. Slightly rougher ride - you feel bumps more
4. Slower descents

[minan]

I have bikes with both 650's and 700's. My road race bike has 700's, my tt bike 650's, my winter bike 650's. My advice - forget about the wheel size and first and foremost find a bike that fits you well. My experience has been the opposite of Tri Girls. My 700c wheel bike fits me the best and I am fastest on it, though I am closer to your size - I am 5' even. My winter bike is no slouch - its a nice light ti frame and try as I might, the geometry is just that little bit different than my race bike and I cannot produce as much power on it. (I'm the longer legged, shorter torso'd variety of short person )

As you've noted getting a good tt position isn't really possible for us shorties on bigger wheels, so yes my tt bike has 650's on it, even at that I don't have a lot of saddle to handlebar drop.

I think this is the most useful advice I've heard, from you and a very few wise others. I'm about equal in leg and torso proportion, according to my original fitter, and he said that is why I am able to fit on the Ruby although he's tried to fit people who were taller than I on the same bike, and was unsuccessful because their torso was too short.

As for getting a good tt position, I think the jury's still out on that for me. Mikael said I *can* get a good tt position on my current bike, just that if I go for 650c I'd have more options.

[Eden]

As for getting a good tt position, I think the jury's still out on that for me. Mikael said I *can* get a good tt position on my current bike, just that if I go for 650c I'd have more options.

I've never tried to set my Ruby up as a TT bike, though I guess it could be done. A bunch of factors made me get separate bikes. I've got the Ruby pro, which has carbon bars, so clip on's are not an option. I also got a screaming deal on a used TT specific bike and it was just a given that in my size it would have 650 wheels. For stage races (which I do probably 4 to 5 of a year) it is sooooo nice to not have to touch my road bike between the TT and road race/crit stages. Changing saddle positions, fussing with handlebars is just something I don't really need to have to think about.

A few plusses about the system are that I still get to ride my 700's for road races - if you have anything non-standard you can forget about getting any neutral support. For TT's support doesn't really matter so much. I was also able to get really good prices on a deep section front and rear disc wheels, as many taller triathletes are switching back to 700c gear and selling off their 650 stuff cheap.(I got my Hed disc for $260! with a cassette)