Adaptor converting frame from Rim to Disc brake


Senior Member
I have just ordered an adaptor which clamps onto the seat stay of the bike which allows disc callipers to be mounted on a bike which doesnt have the required booses:-

1) It only cost me £1.68 [from Hong Kong], are these any good i.e do they work?
2) i got an old front BB5 calliper and wondered if there are differences with front and rear callipers?




Tattooed Beat Messiah
Will, have you a pic or link.

Not sure I would trust it to be honest. How is it attached to the seat stay? P Clips?
Disc Brake callipers need to be very securely mounted due to the forces generated. I can imagine that anything other then proper mounts would mean the calliper moving and having to keep readjusting.
Loch side.
A disc brake generates a strong bending moment over the two mounts and stays have to be beefed up to compensate. This is even more noticeable on the fork. By the sounds of it you will only convert the rear though. Is it an aluminium or steel frame? The former is better since the tubes have a larger diameter. The calipers are the same BTW.


Legendary Member
YEH BUT! the postage is free. OP, what are you hoping to gain?
No way would I consider a bodge like that, for the reasons mentioned above. If you want to convert a bike to disc, then look at doing the front only, as you just need to get a new fork, which you then know is designed for the job.
Exactly what I did with an On-One Pompino. Bike was originally cantis that I struggled to keep adjusted properly. New disc fork from On-One (same paint colour :thumbsup:) with a mechanical caliper and left the cantis on the back. Braking transformed, rear canti was still mostly for appearances though.
I'm with everyone else on this, I'm not sure I'd trust that. I'd be bit worried about it snapping and seizing the wheel.

Having said that, I'm a bit puzzled as to how this works -I see the clamp goes on the seat stay -but the tab fork thingy -does that go in the qr or around the axle?

Ian H

I am an ancient randonneur, & I stop often for tea
East Devon
It's a bodge. It might damage the frame if you put in on the back. It might kill you if you put it on the front.


Cycles in Motion in this fair city of Sheffield convert bikes to have discs at the rear, but it looks a bit like this when they're done:

rear calliper.PNG

i.e. the chain-stay and seat-stay are braced against each other. I'm another in the 'not on my bike' camp I'm afraid!
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