Fleming Posted December 4, 2017 Share 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. Kalahari Vegmot, Ferro, Robrider and 9 others 12 Link to comment Share on other sites More sharing options...
ichnusa Posted December 4, 2017 Share This is properly impressive... I LOVE stories like this! Link to comment Share on other sites More sharing options...
Kalahari Vegmot Posted December 4, 2017 Share Nice! Link to comment Share on other sites More sharing options...
Eddy Gordo Posted December 4, 2017 Share Nice one.Looks pretty industrial!!! Link to comment Share on other sites More sharing options...
TALUS Posted December 4, 2017 Share Jeez it is what being "HANDY" is all about. Congrats coppi 1 Link to comment Share on other sites More sharing options...
TheJ Posted December 4, 2017 Share 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. Link to comment Share on other sites More sharing options...
popcorn_skollie Posted December 4, 2017 Share 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? Kalahari Vegmot and CdT85 2 Link to comment Share on other sites More sharing options...
Reden Posted December 5, 2017 Share Just the thing I want for my Giant Sedona SE frame. I really did not want to silver solder brackets to it.Well done. Link to comment Share on other sites More sharing options...
Fleming Posted December 5, 2017 Share Mountain Bike disc brake Converter v brake rack Disc MTB Bicycle Holder Special frame brake adapter 22mm/31.8mmhttp://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. Link to comment Share on other sites More sharing options...
shaper Posted December 5, 2017 Share 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 Edited December 5, 2017 by shaper Eddy Gordo 1 Link to comment Share on other sites More sharing options...
Mongoose! Posted December 5, 2017 Share 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... Link to comment Share on other sites More sharing options...
CdT85 Posted December 5, 2017 Share 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 Link to comment Share on other sites More sharing options...
Captain Fastbastard Mayhem Posted December 5, 2017 Share That's really, really cool! Well done! Link to comment Share on other sites More sharing options...
Eddy Gordo Posted December 5, 2017 Share 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.JPGDSCI0915.JPGThat one is much better than the china special. Much more solid too Link to comment Share on other sites More sharing options...
Piernas Flacas Posted December 5, 2017 Share Very ingenious, good job! Link to comment Share on other sites More sharing options...
Josh0 Posted December 5, 2017 Share 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? Link to comment Share on other sites More sharing options...
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