Adaptor converting frame from Rim to Disc brake

[Piemaster]

|Can't see youtube here at work. Boo.
AFAIK the Ka-50 does blow rotors off first. Who'd want to be the first to try it out though?

 

[Gravity Aided]

Not me. Afraid they'd blow off at the time inopportune.

 

[139NI]

This above arrangement relies on mounts and bosses present on the bike which are intended to support a pannier exerting a mainly downward force.
It is possible that the bolted on clamp in the picture above could rip itself out of the bosses if enough braking force is applied, as the forces present are more upwards and forwards. This will be particularly the case if there is not much metal wraparound the mount.

The clamp arrangement of the £1.68 item would experience forces forwards and upwards and focused onto the seat stay. I feel that the designs of most MTB seat stays will be able to tolerate the extra force placed upon it by braking. The clamp is also held in place by the 9mm quick release bolt at the opposite end. The axle bolt is more than able to tolerate the force of braking. For these reasons, i feel that there is a strong argument that the £1.68 disc brake clamp could work and is probably more mechanically robust in theory. The reality is how reliable and sound is the clamp...... and how well it sits at the back as its a one-size-fits-all jobbe.

I accept that the £1.68 clamp is a highly unconventional solution for a disc brake conversion, but if it works then i wont need to tinker with adjusting rim brakes and unpredictable rear braking anymore. i have a ROCKSHOX REBA fork at the front which supports a disc brake without mod.

 

[Andy_R]

In an effort to be helpful, instead of decrying the OP's post, have a look here for work arounds using a very similar adaptor. Personally, I wouldn't do it, but people have and have had varying degrees of sucess.

 

[S.Giles]

People are herd animals. When confronted with something new, they'll throw stones at it or ridicule it. Later, when their hero adopts the idea, they'll all queue up to follow suit (and be willing to pay through the nose to do so).

If I sound jaded, it's because I've been observing this particular phenomenon for nearly half a century!

 

[Gravity Aided]

Funny, I've been observing the phenomenon of persons wishing not to spend money on a genuine article, yet waste sums of money on some adaptor that allows them to get near the object of desire. Many horrendous ten-speed bicycles were produces over the years in an attempt to replicate valuable racing machines. Until recently, I was still seeing mountain bike BSO's in the US with one piece cranks. There is always an impostor, and a herd of followers looking to save a dime or two. Better to buy the quality right off. If that is a bicycle with disc brakes, it would be wise to buy a good bicycle with a frame made for disc brakes. Giant does a nice job at a good price.

 

[S.Giles]

Funny, I've been observing the phenomenon of persons wishing not to spend money on a genuine article, yet waste sums of money on some adaptor that allows them to get near the object of desire. Many horrendous ten-speed bicycles were produces over the years in an attempt to replicate valuable racing machines. Until recently, I was still seeing mountain bike BSO's in the US with one piece cranks. There is always an impostor, and a herd of followers looking to save a dime or two. Better to buy the quality right off. If that is a bicycle with disc brakes, it would be wise to buy a good bicycle with a frame made for disc brakes. Giant does a nice job at a good price.

Us poor folk have to make-do with shoddy tat and keep smiling. So long as we look (a bit) like our heroes, that's good enough.

 

[Flying Dodo]

Us poor folk have to make-do with shoddy tat and keep smiling. So long as we look (a bit) like our heroes, that's good enough.

Assuming you're happy to ignore the safety issue though. Sure, on a cast iron bike with massive thick chain stays it would be fine. But if someone tried using that on a thin walled 1980's era racing bike, or on a carbon frame, it would be a recipe for disaster.

 

[Gravity Aided]

Us poor folk have to make-do with shoddy tat and keep smiling. So long as we look (a bit) like our heroes, that's good enough.

You, sir, deserve better.

 

[Smokin Joe]

Us poor folk have to make-do with shoddy tat and keep smiling. So long as we look (a bit) like our heroes, that's good enough.

I think the "Shoddy tat" I would make do with in this case is a rim brake as opposed to some far eastern Heath Robinson contraption of unknown quality. We're not taking about some cheap and nasty handlebar tape here but something that could end up wrapped round your spokes on a fast descent with all the obvious consequences.

 

[S.Giles]

Update: The controversial item arrived from China (or somewhere) a couple of weeks ago. Unfortunately, although it looks like it might work, it doesn't seem to fit my bike, so that's the end of that. I'm destined to have a vee brake on the back and a disc brake on the front for all eternity! The best of both worlds.

At least it arrived, though, so I'm calling that 'another partial success'!

 

[Pat "5mph"]

A wee project I'm doing with my lbs: transferring components from a frame with 2 disk brakes to another frame with only front disk mounts.
I did buy the frame because the mechanic said we could get an adapter, she was with me when I saw the frame. I guess the idea was what @I like Skol did.
We got this ordered.
After much fettling it did not fit, the dropouts are at the wrong angle, not like in @I like Skol's bike. The disk does not reach the pads completely, see picture.
We tried another, bigger diameter disk, still the same.
We also tried the smaller, original disk again with a different adapter, no joy.
It has to be a new suitable wheel, and v-brakes at the back, that is what the frame was designed for originally anyway, it's a Trek.
If it had worked, I think the adapter would have been perfectly safe, once fitted it's immovable from the frame.

 

[I like Skol]

I'm sure you tried it but can't you flip the adaptor to improve things so instead of fitting this way

It fits the other way, which will alter the caliper position quite a bit (hopefully in the right direction).

There are all sort of adaptors, front and rear versions and maybe even 140mm disc ones. Surely one must work?

 

[Yellow Saddle]

I'm sure you tried it but can't you flip the adaptor to improve things so instead of fitting this way
View attachment 83883
It fits the other way, which will alter the caliper position quite a bit (hopefully in the right direction).
View attachment 83885
There are all sort of adaptors, front and rear versions and maybe even 140mm disc ones. Surely one must work?

I agree. Since these adapters are all made to accommodate different disc sizes, @Pat could also try and fit a bigger disc. Sort of using the adapter concept in reverse. Discs come in 140, 160, 180 and 205mm sizes.

 

[compo]

Something not mentioned is the spoking of wheels to be used with disc brakes. Lots of disc specific wheels have a different lacing pattern to those for rim brakes. I don't know how relevant this is but I am sure Shimano have their reasons. (I say Shimano because they mention this in their technical docs for my mechanical disc brakes).