650 bikes

[SamIAm]

What are the reasons someone should consider a bike built for 650 wheels over a 700? What does a 650 do better than a 700? I note that Rivendell is a big proponent of the 650's.

[dbrk]

You do mean 650B correct or 584mm? These are not to be confused with the more popular and current 650C or 571mm diameter used on tri-bikes and often wisely on particularly small road bikes (for a host of good design reasons that need to be taken as a whole, e.g., to avoid TCO, calm angles in design, etc ...). With 650B particular fat tires are available starting with the skinnies at 32c though more commonly 37c and 42c. You can still use fenders too with tires this size and several beautiful options are available from Honjo or Berthoud. With this sort of size and air the overall diameter of the wheel is very close to 700c, effectively giving you the momentum of a larger diameter wheel and the benefits of a stronger smaller diameter but important pneumatic benefits (cushy ride, support over bad roads, etc) rarely achieved. Once a frame gets over a certain size (say, 61cm), the overall effect of 650B doesn't stand up well against the 622mm/700c wheel.

I'm happy to say that I am a lively proponent of riding in this style but to each their own.

dbrk

[samcat]

Dr. Brooks has the bases well covered. I'd add lowered standover hight/lower BB/ lower CG to his list. Small folk on small bikes ride on rails accordingly.

On road bikes smaller than a 52 +/-, 650Cs become a very viable option for the very reasons stated above. That usually translates to a man of 5'5-6", or so, or a woman of slightly shorter stature.

Another viable option would be 559 (26") MTB wheels if you're looking at an all arounder or a tourer.

If Serotta Andrew is lurking, mebbe he could chime in here..He's fitted my spouse on one of each.


PH

[dbrk]

Dr. Brooks has the bases well covered. I'd add lowered standover hight/lower BB/ lower CG to his list.
PH

Hmmm, yes, but one can't lower the bb on the 650B without risking problems with pedals, crankarms. On a typical 52cm bike, for example, the bb drop is likely somewhere about 67mm, which sounds "high" but you have to take into account the smaller (584 vs 622) diameter of the wheels.

Why not just use the more popular 559mm/26" wheel mtn bike size? Some, like me, might say that the small gain in diameter gives you a better roll, more momentum since the smaller the diameter the sooner the bike comes to a halt of its own accord. Some others, like me, would say that it's a great tradition and now there are plenty of rims and tires available so that it need not been a quirky niche (back when I hoarded all I could find from France and Japan). Grant Petersen brought 650B back singlehandedly, bless his heart.


dbrk

[samcat]

My comments referred to 650C and small riders, not 650B and taller folk.

Consequently one would expect shorter cranks, too...tough to snag a crank w/165s...

PH

[SamIAm]

If the ultimate diameter of the 650B wheel + (suitably large) tire is approximately the same as the 700c, why does the design of the bike i.e BB height or crank arms have to change?

[Ray]

My comments referred to 650C and small riders, not 650B and taller folk.

Consequently one would expect shorter cranks, too...tough to snag a crank w/165s...

PHJust to be clear in response, Rivendell isn't a big proponent of the 650c (not that they have anything against them necessarily), but they're doing their level best to spread the word on 650b, with more than a small push from the good Dr. Brooks.

-Ray