What is 650B?

650B is an old tire size designation for what is known today as 584mm ETRO - a currently obscure size, at least in North America, that has been used in the past on some of the finest bicycles.  584mm sits nicely between the standard road bike wheel size - 622mm ETRO (i.e. 700c) - and the standard for off road bikes - 559mm ETRO (i.e. 26").  The tires currently available in the United States range from about 30mm wide to 38mm wide, though there are other sizes available in Europe.


제 3국 포함 , 후진국 투어링시...

700 c 의 스포크와 림을 구하기 어려운 이유가 주된 원인입니다.

강도 문제도 있구요...스포크 거리가 상대적으로 짧아지면서

휠 강도가 증가한다고 합니다...

그래서 26인치 휠셋이 전세계적으로 선호되는 이유 이기도 하지요...

막말로 여행중 극한의 상황에서

리어카 튜브와 휠셋 구성품들을 이용할 수도 있겠지요... : )


You want a softer ride than you can get from any tires that your frame was designed to accomodate.

You want fender/mudguard clearance on a bike that wasn't designed for it.
You like the slightly more substantial looks of the wider tires typical to 650b wheels.
You want to be different.
You want the bike to handle differently.
You want to be able to do some light off-road riding but aren't comfortable doing it with the tires that your frame was designed to accomodate.





Will your bike work?


Maybe.  Certainly not all 700c bikes are ripe for conversion to 650B.  Some things to keep in mind:

You'll probably be dropping the bottom bracket.  If you use long cranks, your bike has quite a lot of drop to begin with - say 7.5cm or more, and/or you are planning to use small cross section 650B tires you'll want to check this one out very thoroughly or make sure you don't pedal through corners.  Various of the 650B tires currently available seem to have radii between 325mm and 334mm.  If you're moving from small section 700c tires, which may have a radius of only 335mm to a wide 650B with a radius of 332mm then your bottom bracket shouldn't be noticeably lower after the conversion.  If you're trying to convert a Rivendell with an 8cm drop and are planning to use 325mm radius tires you'll be looking at a bottom bracket height of only about 9 1/2" - which is very low for anything longer than probably 155mm cranks.
You'll be increasing the distance from the brake centerbolt to the rim surface by about 19mm.  This will thow out cantilever equipped 700c bikes unless you're willing to get the cantilever studs moved by a framebuilder (necessitating a repaint.)  If your bike uses short reach brakes (i.e. 39mm-49mm) it should be relatively easy to find brakes that will work with the additional reach - some sidepulls but mostly centerpulls.  If your bike currently uses long reach brakes (i.e. 47mm-57mm) you may have more difficulty.

There might be problems clearing the chainstays with wide 650B tires.  If your chainstays aren't dimpled and they run fairly close to the rims on your current wheels you might not be able to fit the wider section 650B tires even though the wider portion of the tire will be nearer then hub than with 700c tires.  A quick rule of thumb would be at 320mm from the axle you'll need 42mm of clearance for Col de la Vie tires.

You may be changing the handling quite a bit.  If you are moving from moderately wide 700c tires to moderately wide 650B tires you stand to drop the bottom bracket maybe 15mm or more and shorten the trail by as much as 4mm.  These numbers don't sound impressive but remember that they might be between 6% and 9% of their associated values.  Changes of this magnitude can seem pretty dramatic to some individuals, while others might not even notice them.  Whether the changes are for the better will depend upon the user, though I haven't heard of any complaints about the modified handling yet.