650b conversion of a road bike that already has 700c standard reach brake calipers?

[abalone]

Anybody know much about 650b conversions? I want to convert an old 1980s road bike with 700c wheels to a 650b road bike. The bike has standard read brake calipers. I am concerned that with a smaller size rim, the current brake calipers might not have enough brake pad adjustability to allow me to move the pads low enough to squeeze the 650b rims.

[jmoore]

Long reach brake calipers are your friend, assuming there is enough clearance for the tires

[KidWok]

Seen it done a few times with modern racing bikes using 47mm reach brakes. I believe you just need to get some extra long reach (73mm) brakes.

Found on the interwebs:
https://www.flickr.com/photos/randonneecafe/sets/72157629974118148/

Tai

[goonster]

If you need more than 57mm of reach, longer calipers are available (http://www.rivbike.com/product-p/brsr559allen.htm).

[Waldo]

If you need more than 57mm of reach, longer calipers are available (http://www.rivbike.com/product-p/brsr559allen.htm).

Having ridden these brakes, I would say that their performance is acceptable, but it's not up to the level of standard reach Shimano calipers.

[abalone]

.

I am sorry to destroy everybody's browsing experience with this massive picture. Here is a pic (not my bike) of a very similar bike I saw on the internet with the same 700c standard reach calipers that I have.

Qs:

Do these calipers pictured (which is similar to what I currently have) look like 47mm reach calipers?
What size longer reach calipers do you think I might need to do this 650b conversion?
...and
Assuming I will need to get even longer reach brakes than the one pictured... will newer longer reach calipers stop me from overshooting a corner if I am blasting downhill relatively fast?

[thirdgenbird]

I've used the tektros too. I was surprised at how good they were. Like stated, not like a Shimano or campagnolo short reach, but plenty competent. I would use them without fear or hesitation.

[KidWok]

Those are likely ~57mm reach brakes. They should work fine and will work better if you take out the black pads and replace them with some softer compound brake shoes like these: http://www.ebay.com/itm/like/261357860400?lpid=82

73mm reach brakes might get you to a 650b conversion but only way to be sure is to put a set of 650b's in and measure from fork crown brake mount to rim. If you love this frame a lot, you could probably get a frame shop to braze on some canti bosses and go with mini-v's, which would give you better braking performance.

Tai

[abalone]

That is great news. Thanks for the advice kidwok and everyone.

[Frankwurst]

Here's a start. :beer:
http://www.bikeman.com/bikeman-blogs/650blog/1771-650b-conversion-guidlines

[pcxmbfj]

Just converted a Serotta NHX and suggest you verify that there's a wheel/tire combo that fits first.
I have no margin between tire and chain stay with a 2.5" wide tire that is actually ~2.4".
Planning on talking to a builder to see if the chain stay crimps can be extended because I like it as a 650 better.
Then you'll probably need long reach brakes.

[Kirk Pacenti]

Here's a start. :beer:
http://www.bikeman.com/bikeman-blogs/650blog/1771-650b-conversion-guidlines

^^^ This. Ed Braley is the undisputed master of 650b conversions.

Cheers,
KP

[jasonlee]

Your best bet is to actually measure what you currently have and measure where the 650b rim will need the brake pads. Guessing and "it should be close" will end up having the pads all the way down and still rubbing on the tire.

Some bikes work well for the conversion and some are terrible and have you spending way more that you intended and you would have been better off buying a 650b bike from the beginning - say from one of our forum sponsors.