Dent repair on an old Serotta!

I guess some people do read this blog! I got an email from a guy who has a nice older Serotta. Based on what’s left of the serial number and the traditional sized tubeset, he thinks it’s a 1982. Well, it had about a 10mm dent in the top tube. Totally structurally sound still. Sweet!

Here is how I removed the dent.

When you dent a tube, not only are you pushing material down but you are pushing material out on either side of the dent. The way to get rid of SOME of that raised portions is to use a tube block. The idea is to clamp the tube in a tube block and rotate the frame around the dent. This helps to flatten the high spots and if you’re lucky, pop some of the dent back out.

Cool! Except I don’t have a 1″ tube block. Ha! Figures. So I made one.

Here is my step by step process for dent removal.

Step 1. Sand the paint off all the way around the dented tube.

Step 2. Apply grease to the frame and the tube block. This allows the frame to rotate in the tube block without galling.

Step 3. Clamp the dented part of the frame and tube block firmly in a vise. Now, don’t kill it but it does have to be pretty snug.

Step 4. Rotate the frame along the axis of the tube back and forth several times.

You may notice the vise is a tad lose now. That’s cool! That means the tube is rounder than before. You can tighten the vise at this point and repeat this step. You can always take the frame out and check it for progress at any point. Just be sure to reapply grease.

Step 5. When you are happy with your progress with the tube block, clean off the frame and get ready to fill with bronze.

Step 6. Prep the frame how you would for brazing a joint but make the dent face perpendicular to the ground (straight up) this way gravity will help keep your bronze in place.

Be sure to fill the dent with bronze and then some. You will be removing the protruding bronze, smoothing it to the tube.

Step 7. Soak the flux off.

Step 8. File it smooth! Make sure you don’t remove too much bronze or file too hard into the steel. You don’t want to thin the wall of the tube.

Send it off to the painter!


Hopefully these directions can help someone keep a beloved bike on the road! I love being able to save a classic Serotta! Hopefully I’ve made Ben proud. 😁

The owner will be repainting and rebuilding it with period correct components. Hopefully he sends me pics when done so I can add them here.

Please let me know if I’ve missed anything or if you have questions / critique.