650b conversion - issues

[weisan]

Yes, even before the dust settled with the "crimping" saga, I have opened up yet another case of unsolved mystery.

So, assuming I want to put a 650b wheel on my Merlin Ti cyclocross bike, how do you solve the problem with the canti brakes being too high and not align with the rim brake track?

Please see picture.

[thirdgenbird]

I'm not sure you do. Disc and caliper are easy to convert. Canti is not. Even going from 27in to 700c can pose an issue with canti brakes.

[happycampyer]

Have disc tabs installed? I think it's easier with calipers since you can go from short reach to medium or long reach. Not sure if there is a canti solution.

[bicycletricycle]

Not much to be done about that unless you got a grinder, TIG welder and some argon.

Also, how would you solve your lower bottom bracket height? I guess it might be okay if it is a little high now.

[weisan]

I guess the consensus is..."no go". Thought I might check anyway. According to this chap, it's definitely no go.

"However, bikes that have cantilever brakes are not viable candidates for 650B conversion due to the fixed placement of the canti bosses. The bosses will be right next to the 650B rim and proper brake adjustment is not possible without relocating these brazed-on fittings."

https://www.bikeman.com/bikeman-blogs/650blog/1771-650b-conversion-guidlines

[pinkshogun]

i recently saw a doo-hickey that mounts onto the canti stud post that will drop the caliper enough to line up the brake pad with the rim

i dont remember who makes it or where i saw it but perhaps a google search or a looksy on the bob list or 650b list will help

[weisan]

there's always a solution...well, alright not always, but if only we don't give up so easily or come to a conclusion so quickly...

Elevn Brake Adaptors
http://www.maximumbmx.com/catalog.php?item=1205
http://www.maximumbmx.com/images/large/elvnbrkextnder.gif

V brake Post extender
https://www.danscomp.com/products-PARTS/489052/Elevn_V-Brake_Post_Extender.html
https://b8p4k2y2.map2.ssl.hwcdn.net/large_489052_Elevn_V+Brake_Post_Extender.gif

[marciero]

Not to be annoying, but, speaking of crimping, I would attach the rack at the axle rather than where you have it. You can make a piece for it or use the one you have there, oriented vertically. The setup as shown supports weight by acting as a lever on the stay and has the potential to concentrate the load, esp over bumps, at small point, magnified by the lever action.

[weisan]

Not to be annoying, but, speaking of crimping, I would attach the rack at the axle rather than where you have it. You can make a piece for it or use the one you have there, oriented vertically. The setup as shown supports weight by acting as a lever on the stay and has the potential to concentrate the load, esp over bumps, at small point, magnified by the lever action.

marci pal, good eye! and good advice...I will take it!

[hokoman]

Not to be annoying, but, speaking of crimping, I would attach the rack at the axle rather than where you have it. You can make a piece for it or use the one you have there, oriented vertically. The setup as shown supports weight by acting as a lever on the stay and has the potential to concentrate the load, esp over bumps, at small point, magnified by the lever action.

Could be an optical illusion from the flash, but the seatstay looks bent where you have the rack...

[weisan]

Could be an optical illusion from the flash, but the seatstay looks bent where you have the rack...

No illusion, it is bent...by design :D

[happycampyer]

there's always a solution...well, alright not always, but if only we don't give up so easily or come to a conclusion so quickly...It's an inexpensive experiment. Depending on the roads you intend to ride (especially how long/steep the dirt/gravel escents are), it may be fine. Bear in mind that these extenders would likely add some flex, which isn't a great thing to add to cantis/v-brakes.

[weisan]

It's an inexpensive experiment.

you mean compared to crimping the chainstay? :D

thanks campyer pal.

[oldpotatoe]

you mean compared to crimping the chainstay? :D

thanks campyer pal.

But if ya get them from Dan's Comp, they'll probably only send you one:o

[palincss]

Not much to be done about that unless you got a grinder, TIG welder and some argon.

Also, how would you solve your lower bottom bracket height? I guess it might be okay if it is a little high now.

Usually lower bottom bracket height isn't an issue because the outside diameter of a 650B wheel with 38-42mm tire mounted is within a mm or two of that of a 700Cx23 wheel with tire mounted. However, it is a factor that should be borne in mind (along with whether the bike is equipped with cantilever brakes!) when evaluating a frame as a candidate for 650B conversion.

[weisan]

But if ya get them from Dan's Comp, they'll probably only send you one:o

oh c'mon, old pal ...

There is no sadder sight than a young pessimist, except an old optimist.
Mark Twain

[bgoldenberg]

To use those BMX brake post adapters, the existing canti posts on your Merlin will have to be removable. I can't tell from the picture, but I think that's pretty rare for touring and cross bikes?

The Shimano CX70 brakes give a bit more adjustability than most, so work well for 27" -> 700c conversions, but that's a lot less of a difference than 700c -> 650b. I use a pair on my 1980s Univega Gran Turismo town bike to go 700c -> 650b, but I doubt that'll work here. I think you're probably SOL :(

[oldpotatoe]

oh c'mon, old pal ...

There is no sadder sight than a young pessimist, except an old optimist.
Mark Twain

2 strikes and they are out. The 'phone call', he actually called back, since I went on terminal hold when I called them..sent an email. They threaded the 15g portion of the Race spoke, used too long of a blank and the gent really didn't know what I was talking about. '14/15/14', 'double butted', not single.

I guess that 'thousand yard stare' over the phone bothered me the most, plus I asked for a call tag, and that didn't make him happy.

Plus they seem to not be able to count to 18. GREAT prices. Not sure how they do that. Manufacture to supplier prices with no margin for a Race spoke($.40).

[sparky33]

Bear in mind that these extenders would likely add some flex, which isn't a great thing to add to cantis/v-brakes.


What I think Happy is saying is that you should try the adapters and prove that you will be better off starting over with something like his 650b ti wonder bike.