I got a vintage Cannondale sm600 26er and didn’t realize it had weird brake mounts (picture right). The posts take a nut instead of a bolt. I thought maybe I could swap it with the other post type (one on the left) but it seems that the thread is different. They are close but the old one has a steeper pitch (It looks like visually I’m not familiar with measuring pitches). Anyone know what they’re called and if I can convert to the other post ? Hoping to mount the Paul racer brake.
by heymanmyhiphurts
4 Comments
I’d run to a hardware store and see if you can figure out the thread pitch of the post you removed.. I know there is at least three different threadings you can buy from shops on Ebay.
So these are the uncommon 5/16” 18tpi canti studs used by this era of Cannondale F/Mxxx, Fat Chance and Klein frames.
You can still get them. Here’s what a couple searches turned up as an example:
https://specialtyretroproducts.com/product/srp-titanium-brake-stud-boss-post-for-klein-fat-chance-yeti-and-cannondale-frame/
https://brake-stuff.de/en/canti-studs/15/canti-studs-with-5-16-18-unc-inch-thread-e.g.-for-klein-fat-chance-and-cannondale
Let me guess, the rear brake was a u-brake? Kind of looks like a canti-lever brake with the arms installed backwards?
If memory serves me correctly, the pitch on those early Cannondale was 5/16 -18, the other one looks like 5/16-24. The original post is almost impossible to find now. Most of those I know who have the early bikes with a Suntour u-brake on them just clean and tune up the u-brake with new pads because finding a more typical post to fit that thread pattern is so time consuming/seemingly impossible.
Metric threads have different pitch offerings. A standard M6 would be 1mm pitch but an M6 fine would be M6x0.8. I don’t know if those are M6 threads I’m just saying that’s how the threads and pitches notation works. Brake bosses are probably M8 or even M10
From what I can tell though it’s possible older Cannondale, yeti, Klein and Fat chance frames may have used 5/16 x 18 threads (standard or “SAE” threads note pitch in threads per inch so 18 per inch)
Best thing to do is take it to the hardware store like the other poster replied and find a nut that threads on easily (dont use a locknut) and that will be the thread size you need. There are lots of places online that sell v brake bosses with a variety of thread types.