650 wheels for 46cm custom bike?

[toaster]

A female friend was wondering if a small 46cm custom is better off made for 650c wheels or staying with 700c's.

Your thoughts?

[Tailwinds]

650 fer sure

[samcat]

Spouse went from 700C to 650C on her 46. Much better ride; more proportional looking bike.

IMHO, A 46 frame w/700 wheels looks like a life support system for the hoops...and the angles are all screwed up. The smaller wheels allowed a classic 73/73 geometery. Terrific.

PH

[kestrel]

There's some pretty cool 650 Rolf Vector Pro's on ebay right now.

[Smiley]

Small bike needs 650 wheels for better rider balance across wheel base and to eliminate TCO and solve stand over issues. Its a better ride too boot .

[scrooge]

According to Rivendell's website, any bike that size with 700c wheels must have really wacky seat tube angles to accomadate.

[zap]

My feeling is that any bike 52cm and smaller should have 650c for proper handling. Wheels act like gyroscopes and as your centre of gravity gets lower, leaning the bike over becomes more difficult.

I can't tell you how many guys argue with me over this matter, yet every women I know that switched to 650c bike loves it.

[cpg]

My feeling is that any bike 52cm and smaller should have 650c for proper handling. Wheels act like gyroscopes and as your centre of gravity gets lower, leaning the bike over becomes more difficult.

I can't tell you how many guys argue with me over this matter, yet every women I know that switched to 650c bike loves it.


It's been my experience that when a shortish woman comes to me for a custom and small wheels are the best solution it's almost always her significant other or a male friend is the one balking at the idea. And after he finally decides to relent the women have always been happy with the results. I believe it's nearly impossible to make a bike unrideable so short women and men get "used" to poorly performing bikes. It becomes they way bikes "should" handle because they've never known different. But when they make the switch they're benchmark is altered and they can't imagine putting up with the compromises again.

Curt

[Brian Smith]

nice post.
When you say shortish, what approximate height are you meaning?
Since the average height for American women is around 5'3" to 5'4", I would
think that the woman would not have to stray far from average, if at all, to be
solidly among the beneficiaries 650 wheel sizes.

[Ginger]

I agree that 650 wheels:
a. Make a small bike perhaps more "correct"
b. Help avoid toe overlap and perhaps other design issues on a small bike

But I personally do not like them. I had/have a bike that runs them and I found they didn't roll as well, (and related) they aren't as "comfortable" on rough pavement as 700c wheels, and at the time there was less variety of tires for them.

Fortunately, my bikes could go either way...so I go with the 700.
Your mileage may vary.

I will say that when a woman goes from an awkward bike that does not fit, to a correctly designed custom bike with 650c wheels that does fit, she will probably fall in love with the 650c wheels. *That* said, yeah, I don't know anything about bike design, but a 46 would probably be best with 650c wheels.
:)

[mwos]

I know a lot of riders perceive 650's as slower, harsher, tires hard to get, etc., but I've been riding 650c wheels for over 10 years. I can honestly say I'd never even consider going back to 700's. I don't find them harsher than 700's or much slower. When I demoed the Nove with 700's I couldn't tell you if I was riding a 700c or 650c wheel.

I think the only way to judge differences would be to have 2 identical bikes, one on 650's and one on 700's. Then I might say one is better over the other but since that's not going to happen I'll stick with the 650's.

Kathi

[znfdl]

It is not only the lenght of the seat tube, but the length of the top tube. My wife rides a 58 seat tube with a 49 top tube (Yes she has proprtionally long legs, 34 inch inseam, height is 5' 9"), which was designed by Tom Kellogg. The additional obstacle for her was riding 175mm cranks. After 20 years of seriously riding a bike, my wife says that this is the only bike that she has felt good on.

[Grant McLean]

I agree that the reach is the issue, not seat tube length.

Toe clip overlap can be reduced by increasing fork rake, shallower
head tube angle, keeping the same trail.
It's surprising how many small bikes have only 4cm of rake.

Slope the top tube up towards the headtube for most women,
as the 650c wheel really drops the headset down, and you
can end up with a lot of drop if you aren't careful on a small
level top tube bike with 650's

-Gee

[CNY rider]

Grant, I'm trying to understand what those diagrams are telling us, and I'm just not gettin' it.

Can you enlighten me? I'm not much of a geo whiz I'm afraid, but I'm trying to learn.

[Grant McLean]

CNY Rider,

No problem, but I was only trying to make a single point.
(the bikes look complicated because of all the lines, I should have found better pictures)
If you look at the "drop" of the saddle to handlebar on the Trek in the picture, it's huge. The Giant has very little drop.

What i'm showing is that regardless of wheel size, the seat will be the same height off the ground. Right? OK, well, the same is not true of the handlebars. The fork on a 650 wheel bike is designed for a wheel about 5cm shorter than a 700c wheel. Think about putting a 650 front wheel into your 700c frame. Bars go way down. You need to compensate by using a long head tube to bring them back up.

The Trek has a "level" top tube frame design, and the head tube length is short because it's tied to the small frame size, and they didn't do an extended headtube.

Most women don't want their bars really low, therefore, if Trek either use sloping geometry with a longer headtube, or an extension, the bars would back up higher, even if the seat tube is short.

It's just one of factor that should be taken into consideration when building around 650c wheels.

I'm not sure that makes it any more clear or not!

_Gee

[Tailwinds]

I'm not sure that makes it any more clear or not!



Yes, it does to me!

[CNY rider]

Yes, it does to me!


Yep, what she said!

Thanks.

[Grant McLean]

Yep, what she said!

Thanks.

Great, I'm glad that made some sense.

The other thing to "watch out" for on the so called "womens specific" designs
is steep seat tube angle. Lots of women have a long femur.
(that comes in the package of having a long-leg, shorter torso proportion.)
Even short women can have a high ratio between the upper and lower leg. That can
mean that they acutally might like their seat back, behind the pedals,
not in front. The steep seat tube is often a "cheat" to shorten the top tube
to make you think the reach is shorter.

Most fitters start with positioning the saddle first, and if you have to move
the saddle back a lot, you just re-lengthened the cockpit again!

If i've not lost you yet, I'll bring up the toe clip overlap issue again.
Overlap can be almost eliminated by increasing the fork rake and
making the headtube angle shallower. This keeps the handling neutral
by keeping the "trail" constant, yet moves the front wheel away.

It's a neat trick, and i don't know why more designers don't use it, maybe
it's becuase they would have to spec. more than one size forks on all
their bikes. It couldn't be because they don't know about geometry,
can it??

_Gee

[scrooge]

Lots of women have a long femur.
(that comes in the package of having a long-leg, shorter torso proportion.)
Even short women can have a high ratio between the upper and lower leg. That can
mean that they acutally might like their seat back, behind the pedals,
not in front.


Ah ha! Perhaps this is why my wife always seems to slide so far back on her seat?