DIY Disc Mount for Retro Frame

[Fleming]

A while ago I posted a thread about my 1995 Kona Explosif. I have had the bike for a few years and tried a few different builds and finally settled for a "Retro-Mod" build which is basically a retro frame with modern components. The one issue that bugs me with such a build is the frames inability to mount disc brakes. This meant that I had a V-Brake at the back and a disc at the front. Not exactly elegant. Some might call it a "Mullet."

 

I looked at getting a mount welded on but decided against it as the cost would be rather high in comparison to the frames value. Also, I might want to restore the bike to a period correct build in the future. I looked at bolt on adapters but they are few and far between and the ones that are available dont look very good. They look flimsy or are suited to chunckier aluminium frames. Eventually I decided to try make my own. As Jeremy Clarkson always says "How hard can be?" It also helps that I work in engineering and have access to some pretty cool design tools.

 

Step one was getting a 3D model of my frame. I stripped off a few components and "scanned" the frame using a very high resolution GOM 3d metrology scanner. This gave me a very accurate 3D model to design the disc adapter around.

 

 

Next I used Inventor CAD software to design a bracket that is simple to manufacture, relatively light yet strong. Its very similar to an idea Specialized had to retrofit discs to some of their old bikes called a "Sharkfin" Its not as elegant looking but I wanted it to be simple and cheap to manufacture.

 

 

I did a bit of FEA on the bracket to check its strength. To be honest I have no idea what sort of forces a typical disc brake generates but can tell you that if bike designers used my assumed forces bikes would have a lot more material around the drop out.

 

 

Finally I had it manufactured and fitted it. I did modify it a little by drilling a hole to cable tie the brake hose. Otherwise it fitted perfectly.

 

 

 

 

 

Only issue is I discovered the caliper was leaking mineral oil all over the disc and pads so I haven't had a chance to test it. Its at the LBS getting sorted and hope to take it for a proper test this weekend.

 

 

 

 

 

 

[ichnusa]

This is properly impressive... I LOVE stories like this!

[Kalahari Vegmot]

Nice!

[Eddy Gordo]

Nice one.Looks pretty industrial!!!

[TALUS]

Jeez it is what being "HANDY" is all about. Congrats

[TheJ]

Mountain Bike disc brake Converter v brake rack Disc MTB Bicycle Holder Special frame brake adapter 22mm/31.8mm

http://s.aliexpress.com/67zQveYj

(from AliExpress Android)

 

The U bit replaces a spacer on your non drive side of the axle and the clamp goes around the frame. Instant disc mount.

[popcorn_skollie]

A friend of mine bought the seat stay clamp solution for an old trek. From Alibaba.

Took 600 years to get here and its fair to say the product is underwhelming to say the least.

Your solution is far more proper. Well done. I have to say though. It sticks out like a girls mustache. And color might make it worse. The bike is so pretty especially the old paint. 

 

Could you make it a bit more like this?

 

[Reden]

Just the thing I want for my Giant Sedona SE frame. I really did not want to silver solder brackets to it.

Well done.

[Fleming]

Mountain Bike disc brake Converter v brake rack Disc MTB Bicycle Holder Special frame brake adapter 22mm/31.8mm

http://s.aliexpress.com/67zQveYj

(from AliExpress Android)

 

The U bit replaces a spacer on your non drive side of the axle and the clamp goes around the frame. Instant disc mount.

I considered this but was afraid it would put all the load into an area of the seat stay which isnt designed for it. It is probably fine for gentle riding but I weigh 90kg and ride my bike hard. I have seen a few threads on some international forums where guys have brazed on a disc mount and they have always reinforced this area with a strut between the seat stay and chain stay.

 

A friend of mine bought the seat stay clamp solution for an old trek. From Alibaba.

Took 600 years to get here and its fair to say the product is underwhelming to say the least.

Your solution is far more proper. Well done. I have to say though. It sticks out like a girls mustache. And color might make it worse. The bike is so pretty especially the old paint. 

 

Could you make it a bit more like this?

 

 

I agree it does stick out a bit. Your rendering looks awesome but I think cutting out such a big hole would make it too weak. I had to rely on favors from friends to manufacture the bracket (paid for in beer) so didn't want to make it too complicated. I may paint or anodize it soon to match the bike a bit better.

[shaper]

Nice bit of Engineering and cool project !!

 

I used one of these a few years back on a Trek 4000

 

http://www.wigglestatic.com/product-media/5360033039/A2Z-retrofit-med.jpg?w=430&h=430&a=7

 

 

 

Got if from Wiggle http://www.wiggle.co.uk/a2z-universal-disc-mount/

 

This is what it looked like on the bike

 

[Mongoose!]

that is really nice!!!

wonder if one can make such thing for a carbon road frame as well...and mount the top part to the arch above the wheel that holds the calliper...

[CdT85]

A while ago I posted a thread about my 1995 Kona Explosif. I have had the bike for a few years and tried a few different builds and finally settled for a "Retro-Mod" build which is basically a retro frame with modern components. The one issue that bugs me with such a build is the frames inability to mount disc brakes. This meant that I had a V-Brake at the back and a disc at the front. Not exactly elegant. Some might call it a "Mullet."

 

I looked at getting a mount welded on but decided against it as the cost would be rather high in comparison to the frames value. Also, I might want to restore the bike to a period correct build in the future. I looked at bolt on adapters but they are few and far between and the ones that are available dont look very good. They look flimsy or are suited to chunckier aluminium frames. Eventually I decided to try make my own. As Jeremy Clarkson always says "How hard can be?" It also helps that I work in engineering and have access to some pretty cool design tools.

 

Step one was getting a 3D model of my frame. I stripped off a few components and "scanned" the frame using a very high resolution GOM 3d metrology scanner. This gave me a very accurate 3D model to design the disc adapter around.

 

Frame Scan.jpg

 

Next I used Inventor CAD software to design a bracket that is simple to manufacture, relatively light yet strong. Its very similar to an idea Specialized had to retrofit discs to some of their old bikes called a "Sharkfin" Its not as elegant looking but I wanted it to be simple and cheap to manufacture.

 

Disc.jpg

 

I did a bit of FEA on the bracket to check its strength. To be honest I have no idea what sort of forces a typical disc brake generates but can tell you that if bike designers used my assumed forces bikes would have a lot more material around the drop out.

 

FEA crop.jpg

 

Finally I had it manufactured and fitted it. I did modify it a little by drilling a hole to cable tie the brake hose. Otherwise it fitted perfectly.

 

Bike (2).jpg

 

PC026035.jpg

 

PC026036.jpg

 

PC026038.jpg

 

Only issue is I discovered the caliper was leaking mineral oil all over the disc and pads so I haven't had a chance to test it. Its at the LBS getting sorted and hope to take it for a proper test this weekend.

 

Top notch restore and upgrade. I have an old cro-mo Diamondback frame sitting at home waiting for a similar mod to bring it back to life. Plan to start the build next year.

 

Nicely done

[Captain Fastbastard Mayhem]

That's really, really cool! Well done!

[Eddy Gordo]

Nice bit of Engineering and cool project !!

 

I used one of these a few years back on a Trek 4000

 

http://www.wigglestatic.com/product-media/5360033039/A2Z-retrofit-med.jpg?w=430&h=430&a=7

 

 

 

Got if from Wiggle http://www.wiggle.co.uk/a2z-universal-disc-mount/

 

This is what it looked like on the bike

 

DSCI0916.JPG

DSCI0915.JPG

That one is much better than the china special. Much more solid too

[Piernas Flacas]

Very ingenious, good job!

[Josh0]

That is awesome Fleming!

 

Well executed project using your work experience and resources. How did you work around the hub spacing change with the bracket on the inside of the stays?