Drilling aluminium frame for brake?

[Tom _M]

Have acquired an old Cannondale frame I want to build up as a singlespeed, though on a tight budget. It originally had a rear hub gear/coaster brake, so though horizontal drop-outs, there are no mountings for a rear brake.

I was considering drilling through the chain stay and putting a bolt on (long reach) calliper on there? Would this be a terrible idea and potentially knacker the frame?







My other thought was to use something like this approach with plates that just clamp onto the chain stays sandwiching them. I’d probably just get a couple of bits of metal and drill as appropriate myself.



Any other thoughts or options I might have overlooked?

[Barchettaman]

Build it up with a single speed coaster brake hub.

[gazza285]

That is the seat stay. You could call into your local bike shop and see if they have any of the old concave washers that were used to stop the brake bolt from crushing the tube.

Or do it properly and go fixed.

[Tom _M]

gazza285 said:

That is the seat stay. You could call into your local bike shop and see if they have any of the old concave washers that were used to stop the brake bolt from crushing the tube.

Or do it properly and go fixed.

I don't know why I typed chain rather than seat stays. Twice. I'm blaming my cold-addled brain. I don't really like fixed on the road when it comes to downhills, so staying singlespeed. Have also got a wheel I can use already, so don't really want to get another if can work around it to use coaster.

[Domski86]

Whether you drill the stays or use some ghetto clamp, you'll need very long reach callipers to reach the wheel. Doubt there would be all that much braking force.

I'd drill it and fit something like this to use modern short reach calipers:

https://campaign.aliexpress.com/wow/gcp/tesla-pc-n...

Having used long reach calipers with 700c wheels on an old steel 27" frame, the performance was less than adequate.

[Donbot]

I'd be nervous about drilling holes in load bearing parts of the frame. I'd probably prefer to not bother with a back brake.

[jrb43]

I built my Dad a bike using a SRAM Automatix rear hub. 2 speed with automatic shifting (centrifugal) and a kick back brake. Honestly, really quite cool. Don't recall it being that expensive though think I had to buy it in Germany or something.

[anonymous-user]

gazza285 said:

the brake bolt from crushing the tube.

Yes - I think this is the issue. Brake callipers have to be fixed quite tight to the frame, and unless there’s some additional material to protect the frame where you drill it I reckon you’ll end up squashing the tube when you tighten the calliper bolt.

Not an ideal bit of frame to weaken, either. Hit a few too many divots with your rear wheel and you’ll find out why.

[Gribs]

If it'll fit I'd be considering something like this and a clarks disc brake.

https://winstanleysbikes.co.uk/a2z-universal-disc-...

[YankeePorker]

BlackWidow13 said:

gazza285 said:

the brake bolt from crushing the tube.

Yes - I think this is the issue. Brake callipers have to be fixed quite tight to the frame, and unless there’s some additional material to protect the frame where you drill it I reckon you’ll end up squashing the tube when you tighten the calliper bolt.

Not an ideal bit of frame to weaken, either. Hit a few too many divots with your rear wheel and you’ll find out why.

If making a hole here ends up being the best solution, then consider getting a suitably equipped friend/shop to drill a larger hole than needed then TIG a length of aluminium tube in the hole. This will avoid too much frame strength from being lost and allow the bolt holding the callipers to clamp across the length of the tube rather than crushing the frame.

[Domski86]

YankeePorker said:

If making a hole here ends up being the best solution, then consider getting a suitably equipped friend/shop to drill a larger hole than needed then TIG a length of aluminium tube in the hole. This will avoid too much frame strength from being lost and allow the bolt holding the callipers to clamp across the length of the tube rather than crushing the frame.

Agree in principle, but by the time you've paid a shop/mate to do this or source additional parts etc you might as well have just got a more suitable frame.

Sometimes it's best to cut losses and get something that will work in the way you want rather than trying to make the wrong part fit. Bodge it for cheap/free or get the proper thing, spending good money after bad is never worthwhile.