Frames: Repairing Cosmetic Damage from a Kickstand

 

A kickstand can be a convenient accessory on a bike. They can allow the bike to be parked in a wider variety of places, and can help steady the bike when parked. Many bikes do not require a kickstand, and some bikes particularly should not have kickstands at all. But many old-school, steel utility and commuter bikes have kickstands or came with them when new.

 

With the kickstand comes the potential for damage to the frame. Most kickstands are of the center-mount type, meaning they clamp onto the bottom bracket by pinching the chain stays right behind the bottom bracket shell. This often leads to damage if the jaws of the stand clamp are over-tightened and if a rubber liner is not used to pad the chain stay tubes.

A note on damage: many times the damage to a bike frame from a kickstand is cosmetic. But sometimes it is so severe as to make the frame unsafe to ride. This is true where there are very deep cuts across the chain stay tubes, where cracks in the tubes radiate from the damage, or where the tubes start to disconnect from the bottom bracket. In those cases DO NOT ride the bike. Instead, take the bike to competent frame builder for inspection. Also, do not ride aluminum or carbon fiber frames that have been damaged due to a kickstand (many of those frames will not even have provision for a clamp-on type kickstand).

 

Let's take a look at repairing some cosmetic kickstand damage on a steel frame Schwinn New World bike from 1941. The culprit is the Miller Kickstand.

The Miller model kickstand was popular in the 1940s, one of the early center-mount kickstands to gain wide popularity in the USA. As popular as it was, the Miller stand had a flaw: the jaws used to secure stand to the bike were thin and could leave cuts across the chain stay tubes. The cuts in my New World frame were not overly deep. They were cosmetic in nature.

I start with JB Weld epoxy. I mix it according to the directions on the package.

I work layers of JB Weld into the cuts until they are built up slightly above the surface of the tubing. Then I let it cure for several days. Because I'm layering the JB Weld, I want to give it some extra time to cure before sanding.

At this point, I have some blobs of JB Weld on the chain stay tubes. Now it is time to sand them down. I mask off the area around the JB Weld with masking tape.

Sanding is done parallel to the direction of the tubes (running along the tubes, not across them). I start with 220 grit and then finish off with 400 grit sandpaper. I work carefully to try to maintain the shape of the tube, so that I have a relatively smooth, round surface when I'm done. This is done by eye, but with some care, a satisfactory result is obtained.

Final painting is done with an oil-based paint. Do NOT use an acetone-based paint (e.g., automotive paint) because it will soften the epoxy. An oil-based paint works fine on the epoxy. 

The result will be a relative smooth, even finish that eliminates the cosmetic damage from a kickstand. This method cannot repair structural damage, which requires a frame builder to address. But using epoxy, you can repair unsightly cosmetic damage from a vintage steel frame and reach a decent result.