650b conversion, brake ponderings

[AngryScientist]

i took my drop bar conversion MB-3 out the other day, and must say, i really do like the geometry and the fit with the drop bars.

since swapping to aero brake levers though, braking is quite sub-par.

i've also been a bit 650b curious, especially with all of the cool tire choices that are currently available.

i need to go do some measuring, but any opinions putting a set of 650b wheels on this and giving it a go. would love to wind up with a front paul racer brake, or similar.

https://1.bp.blogspot.com/-7CcZVFaSx3I/WPVF7b78ofI/AAAAAAAACxU/p-PcpVx3xDgcQd5l7YPKVbrt_mbYGBj8wCLcB/s1200/IMG_0447.JPG

[belopsky]

This will not work with your current brake setup. You have 26" wheels which are 559mm. 650B is 584mm. You need 25mm more vertical movement.

If you get a pair of Paul Motolite, then it may. They should have enough vertical adjustment for the 584mm wheels. Honestly, I don't know why you would on this bike. I understand people going from 700c down to 650b for more clearance and a wider tire, but to go from 26" to 650B I do not think you'll gain anything worthwhile.

[Ed-B]

The thing to do would be to get better brakes for the 26" wheels. Putting 650B wheels on 26" wheeled frames with cantilever brakes is really not practical. Oh, you might be able to make it work, but it's not optimal.

The cantilever bosses are fixed on these old steel frames, and your brake options are limited and braking performance is likely to be poor. And then there's the raised bottom bracket height that you'll have with 650B wheels. Finally, you got some big 26" tires in there now, and I don't think a comparable 650B tire will fit.

Personally, for this bike I'd use mini-V brakes or V brakes with drop levers that have the correct cable pull. If a 90mm mini-V brake will clear the top of the tire that might be your best bet. Take a measurement from the canti boss to the top of the tire to see what might fit.

You'd be much better off trying 650B on a modern disc brake bike, unless you already own a sport-touring 700C caliper brake bike with sufficient clearances. If you need to buy a frame, buy a disc frame or a complete bike. There have been some remarkable deals on new/leftover 700c disc brake bikes, and factory built 650B disc mtb wheels are very common now.

[AngryScientist]

This will not work with your current brake setup. You have 26" wheels which are 559mm. 650B is 584mm. You need 25mm more vertical movement.



12.5mm actually.

[AngryScientist]

You'd be much better off trying 650B on a modern disc brake bike, unless you already own a sport-touring 700C caliper brake bike with sufficient clearances. If you need to buy a frame, buy a disc frame or a complete bike. There have been some remarkable deals on new/leftover 700c disc brake bikes, and factory built 650B disc mtb wheels are very common now.

thanks for the ideas Ed.

to be clear, i certainly dont "need" any additional bikes, :banana:

just thinking of toying around with the set-up on this one as a winter project.

[559Rando]

Was the braking better with non-aero levers? Or was the braking better with the original flat bar and MTB levers?

A few ideas and comments:
1) As other said, you already have fat, slick 26" on there so you probably won't gain any more cush with 650B. It's going to cost you money, tire clearance and may raise the BB (depending on tire choices).

2) If you're 'B-curious, this might be a good test sled with the right calipers and levers. I'd see if mini V brakes will work. If they do, then you can keep the aero levers or upgrade to something else that may improve braking. If not you could go to full size V brakes and Tektro RL520 levers (drop bar/linear pull)

3) You could go to centermount brakes like the Paul Racers if you have enough reach. Measure, measure, measure before you order some expensive brakes! (And even then you may like some different brake levers!)

[ColonelJLloyd]

You will try 650B and I think that with the right bike you're going to love it. At your weight 650Bx42 options are going to be killer. For reasons cited above and more, this isn't the bike.

Now, if you find a go-fast road bike that you can convert to 650Bx42 I think you'd have a lot of fun.

[AngryScientist]

thanks for the advice guys.

i'm probably going to build myself a set of 650b wheels over the winter and give it a whirl, with some different front brakes on this thing, just to see.

well, maybe...

[sowestport]

This will not work with your current brake setup. You have 26" wheels which are 559mm. 650B is 584mm. You need 25mm more vertical movement.

If you get a pair of Paul Motolite, then it may. They should have enough vertical adjustment for the 584mm wheels. Honestly, I don't know why you would on this bike. I understand people going from 700c down to 650b for more clearance and a wider tire, but to go from 26" to 650B I do not think you'll gain anything worthwhile.

I would go with the Motolite (classy). You can even use 700c wheels. Since you have road brifters, you will need this to adjust for the short pull of your levers:

https://problemsolversbike.com/products/brakes/travel_agents_-_6416/?products/travel_agents/

[Ken Robb]

[QUOTE=Ed-B;2268363]The thing to do would be to get better brakes for the 26" wheels. Putting 650B wheels on 26" wheeled frames with cantilever brakes is really not practical. Oh, you might be able to make it work, but it's not optimal.

The cantilever bosses are fixed on these old steel frames, and your brake options are limited and braking performance is likely to be poor. And then there's the raised bottom bracket height that you'll have with 650B wheels. Finally, you got some big 26" tires in there now, and I don't think a comparable 650B tire will fit.

Personally, for this bike I'd use mini-V brakes or V brakes with drop levers that have the correct cable pull. If a 90mm mini-V brake will clear the top of the tire that might be your best bet. Take a measurement from the canti boss to the top of the tire to see what might fit.



You'd be much better off trying 650B on a modern disc brake bike, unless you already own a sport-touring 700C caliper brake bike with sufficient clearances. If you need to buy a frame, buy a disc frame or a complete bike. There have been some remarkable deals on new/leftover 700c disc brake bikes, and factory built 650B disc mtb wheels are very common now.[/QUOTE

]The stock cantis on my 1989 MB-3 worked great with the stock MTB Levers so I think some of the devices that improve compatibility of road levers with canti brakes will probably solve this problem.

[marciero]

Not to discourage you from building up a set of 650b-join the party- but that thing is pretty rad as she sits, especially with those tires. You could likely get better braking with Paul touring cantis or some v-types-Paul or otherwise-without resorting to travel agent-type workarounds.

[skouri1]

V brakes are great
Even the cheap ones on my 15 year old specialized do the job .
You should be able to find some on the cheap
I have trps on my cross bike (8.4 I think) they're WAY powerful

[oldpotatoe]

This will not work with your current brake setup. You have 26" wheels which are 559mm. 650B is 584mm. You need 25mm more vertical movement.

If you get a pair of Paul Motolite, then it may. They should have enough vertical adjustment for the 584mm wheels. Honestly, I don't know why you would on this bike. I understand people going from 700c down to 650b for more clearance and a wider tire, but to go from 26" to 650B I do not think you'll gain anything worthwhile.

Would 650b wheels/tires even clear the frame? I would think the tire would hit the brake bridge down by the BB or between the seat stays.

[Pastashop]

http://www.sheldonbrown.com/cantilever-geometry.html

you need to hit approximately 4:1 lever ratio to get adequate pad-to-rim clearance for the typical range of motion of your hand. For road style levers, regular canti brake arms provide adequate ratio. Shimano "aero" levers tend to hit a sweetspot, others are close.

brake arm stiffness is usually sufficient, but the headset-mounted brake cable hanger can be quite flexy. get this instead:

http://www.retrobike.co.uk/forum/files/cxm_cyclocross_interbike_day3travis_brown_ss_canti _hanger_191.jpg

(tighten the bolt well) or do this:

http://cdn.mos.bikeradar.imdserve.com/images/news/2011/02/27/1298775080901-17wrw52zlidly-630-354.jpg

adjust the yoke position a bit lower. and get the salmon colored KoolStop brake pads.

[weisan]

Braking is over rated.