I recently picked up a 1990 Gazelle Primeur which I am restoring, and one item is replacing the frame lock. Whoever owned this bike removed the frame lock by snapping it off of the frame, leaving two jagged/sharp holes in the seatstay. I'm planning on welding some threaded bosses to these.

Does anyone know what size metric bolt thread frame locks use? Is there a standard size?

I'm going to be using the AXA Victory. I checked their website for specs, but the only info they give is "Mounting Material Not Included." I've searched around and can find no information on bolt sizes commonly used for these.


Seatstay hole

Looks like the holes are 5.5mm so probably 5mm bolts.

Wow, cool! Where did you find that diagram!?

There were a few photos from the link you provided. Scroll to the last one.

Ugh! I'm a doofus. Thank you so much.

I HAVE BEEN QUOTED! (I always love how official those emails make it sound. )

I will be absolutely sure to post updates. The bosses, I think I might be able to use some stainless steel rivnuts (rivet nuts). I just need to make sure they'll expand enough so someone just can't rip the lock out. Might not need to weld at all!

Just had the new bosses brazed on! Took them to a local frame-builder and he had them done in about 20 minutes.

Here's the whole brazing video:
Some still-pics of the process.


Sanding the area all around the tubes

Sanding off the bosses

Adding the bosses onto the tubes, along with plenty of silver flux



The finished brazing job

M5 bosses attached, ready for frame lock!

Just one last quick update on this! This was after the paint job I did. It was a few weeks ago. The entire bike is finished now!! The touch-up paint is a little darker than I would've liked but man was that tough to match! It's more noticeable in pictures than in person. The Velcro holding the brake lines are temporary until I find plastic push-rivets that are small enough to fit into the tube and the clamps.

And talk about irony. The moment I attempted to put my saddle on I realized the tension screw is stripped, so I need to replace that tomorrow. Blegh.

But yes! I feel accomplished. New brake lines, levers, lights, dynamo wiring, rebuilt Sturmey-Archer hub, resurfaced drum brakes, clamps, coat guards, frame lock, frame pump! My first time doing all this!

super nice, and fun to see watch what some who knows what they doing work I bet. and saved me from saying braze, not weld