English => How-To => Topic started by: jm on January 29, 2011, 07:18:39 AM

Title: dropout modding
Post by: jm on January 29, 2011, 07:18:39 AM
Note: This article is to be used as a reference only. I am not condoning nor do I officially recommend anyone try this :)

I recently ran into a pickle with a frame; to install and remove the wheel, adding a half link to the chain was necessary, making the rear end just a tad too long for me. My solution was to modify the drive side dropout to allow the shorter chain, and enough room to take off the wheel without opening the chain.

The tools I used were: electric angle grinder (or a file if that's what you have), a black marker, a straight edge, a round object to draw a radius, and safety glasses.


I began by extending the lines of the dropouts, then following the curve. I guessed I'd need to extend the slot about 1/4", but because that was a guess, I removed just a little at a time, and tried to fit the wheel to avoid cutting too much.

Basically extended the lines on the dropouts, then worked the center of the radius, and back to the lines. Slowly.

I only modified the drive side dropout. I don't know if that is the best method, but I figured the less I did to the frame, the better.


I also went ahead and took some material off my adapter that sits in the axle slot, on one side where it meets the front of the opening. It allowed just that much less material to be removed from the frame.


After all material was removed, in several stages, the final fitting of the wheel was complete. Had I taken any more out, the peg would have rested on the weld; no good. It's best to figure out how far you can/should go with the extension before you begin, so you don't run into a problem like that.

The frame I have fits tight to the wheel as it is, but with a 1.9" tire there is still room. As you can see, the wheel sits straight and true even tho only one dropout was modified:


I only used an angle grinder for this, so it's not perfect. If you attempt this, BE SAFE, and GO SLOW. Remove/fit little by little.


disclaimer: I do not take any responsibility for any harm to bicycle frames, or readers who get hurt trying this. Grinding your dropout will likely void any manufacturers warranty, and has the potential of leading to frame failure and serious personal injury. This should not be attempted by anyone without extensive experience modifying bicycle frames. That been said, best of luck to you.

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