Question: I have an aluminum single-speed frame that was marketed as a fixie. I'm wanting to convert it to a single-speed commuter. (I'm getting older and the fixie doesn't agree with my knees anymore.) It has enough clearance in the rear for 700x35 tires. It has a brake bridge but it doesn't have posts to mount v-brakes or cantilevers. Is there any kind of adapter that could make that work?

Answer: 
Adapters like this do exist, e.g. <http://www.danscomp.com/489051.php?cat=PARTS> or <http://www.bentechbikes.com/vbrakes.htm> (Edit: Links are now dead, but they were basically the same as the one in the photo below. Sourcing one might be even harder now though.)

In fact I used one on my old folding bike - but you can see it looks a bit of a mess, and when I tried it on the front fork, it really wasn't up to the job (I ended up using a chunky long reach caliper brake taken off a BMX bike). (I'd changed wheel size and was using much fatter tyres, so the original brakes wouldn't fit.)

There are also adaptors that bolt around a chainstay: <http://www.ratrodbikes.com/forum/viewtopic.php?f=1&t=33168&st=0&sk=t&sd=a&start=30>

I'm not saying I'd recommend you use them, but the option is there (if sometimes hard to find - the one I used was the last the local store had in stock of a discontinued line).

![V-brake adaptor on my old folder](https://i.stack.imgur.com/CtYHa.jpg)
They are not cheap ($130 front & rear), but Campagnolo makes a lateral pull TT brake that mounts on the center post:

[http://www.amazon.com/Campagnolo-TT-Brake-Front-Lateral/dp/B0057P8SFM/ref=pd\_sim\_sbs\_sg\_1](http://rads.stackoverflow.com/amzn/click/B0057P8SFM)

But, wouldn't it be easier to mount side-pull caliper brakes? You can buy a pair of good-quality dual pivot side-pull calipers for $40-$60, and they will just mount on the single-bolt brake bridge you already have.