In that case, the only option I can imagine that doesn't involve "FIRE - 
and lots of it!" would be to mount centerpull calipers, assuming that the 
brake shoes will fit between the brazed-on canti posts. That way, you can 
test whether the smaller wheels deliver whatever payoff you're looking for, 
before removing/rebrazing the posts.

https://www.youtube.com/watch?v=cDfqwHck2Qg

The logistical problem is that while the pivots of caliper brakes are above 
the brake shoes and the outer circumference of the tires/rims, the pivots 
of canti/V-brakes are below all those things. However much you lower the 
brake shoes/pads on Motolites, you can't get them below the canti 
post/pivot, which is where they'd need to be in order to hit the rim on a 
smaller-than 700c wheel. The only way to ensmallen the wheel would be to 
reverse the brake, putting the shoes below the posts. But then how would 
you get the cable to the brake, with the wheel in the way?

I recall seeing photos recently of some 50's-era French *constructeur* 
brake: A post-mounted, cam-operated thing where the shoes pressed in 
directly from the sides. In theory, one could flip the elements of those 
and reduce the size of the wheel, with a somewhat longer straddle cable. 
I'm guessing that if those had worked well, there would be a lot more of 
them around.

That's another possibility that might work with some monkeywrenching: A 
French-style post-mounted centerpull brake, typically used on 650B townie 
bikes. These put the shoes/pads below the pivots, as if they were Motolites 
with arms extending below the pivots. Bebolux is one of the more common 
brands, but there were a lot of others. Here's the idea:

http://www.blackbirdsf.org/brake_obscura/images/road/moreau.jpg

My guess is that none would fit your canti posts directly; Paul's Racer 
centerpulls specify that they use canti posts, not the smaller Mafac posts 
that French centerpull brakes typically use. The Motolites will use the 
same posts. But shouldn't it be possible to ream out the pivot holes in a 
French brake and press-fit a brass sleeve into the hole, in the manner of 
Compass/Rene Herse's Mafac replacement bearings?

The first thing to try is also the cheapest: Find a long-reach set of 
centerpull calipers (Weinmann or Dia-Compe 610, 750), see if the shoes can 
be squeezed between the canti posts, and see if they'll get down far enough 
to hit your preferred rim.

Or you could approach the problem from the other direction: Since you 
haven't bought an Appaloosa yet, don't. Instead, buy something that's 
designed around 650B wheels. Then you can use Motolites to run 700c wheels 
(with narrower tires). Or if you buy a frameset without braze-on posts at 
all, then you can switch wheel sizes by replacing brake calipers.

Peter "horses for courses" Adler
Berkeley, CA

On Friday, September 6, 2019 at 11:23:24 AM UTC-7, Justin Wyne wrote:
>
> Ah yes, I see how my posting could be confusing. The sentence should 
> possibly read "tempts a fella to put the Paul motolite to the test if the 
> brakes work in the reverse *of* 26" to 650b or 700c and will acomodate 
> 700c to 650b"
>
> I'm thinking of the possibility of changing a size 58 700c Appaloosa to 
> run 650b. The inspiration for this swap is due to already having a 650b 
> wheel set and not yet having an Appaloosa. I have no worry of a low BB on 
> the Appaloosa, that was the skirting of Riv advice I mentioned in the 
> original post. I've ridden plenty of bikes with low BB and have always been 
> able to adjust my riding if need be to dull and possible danger.
>
>>

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