Saturday, December 8, 2012

Repairing Dents in Fenders

Many old bicycles have fender. I love fenders and would not own another bike without them. I think they add a lot in the way of looks and function to a bicycle. They sort of make the "roadster" bike look like it does. A nice set of fenders go a long way to improving how a bike looks, not to mention handles wet conditions.


The Schwinn New World bicycles have fenders, but they've taken a few dings. Other spots on them need a little light reshaping. Removing dents from bicycle fenders is more art than science, but with some practice and care can be done reasonably well with household tools and patience.

Method 1: Fender Rolling

This involves running the fender along the surface of a metal wheel pushed up against a form. As the wheel turns, pressure between the form and the wheel remove any dents. With care, such a wheel can quickly and easily remove dents, leaving the fenders in a much improved condition. An  example of a roller can be seen below:


The problem with rolling is that you need not only the roller, but the form on the roller needs to match the fender you want to correct. A roller for a balloon tire bike fender likely will not work very well for someone wanting to roll a light weight fender, like those on the New World. Moreover, "rain gutter" type fenders like you see on antique bikes from the 1920s/30s, as well as Raleigh Dawn/Sports/Superbe won't work very well either. I can't do fender rolling because I do not own a roller.


Method 2: Pounding


Pounding out dents with a ball peen hammer is nothing new. It's more an art than a science and takes a certain touch. However, once you get a feel for your piece and what kind of force is needed, you can work fenders into a satisfactory shape using just a hammer and form/striking surface.

First, I take a small wooden block and make a semi-circular cut into it matching the contour and shape of the fender I want to work.

Second, I take some WD40 and rub down both the inside and outside of the fender. The creates a shine that will reveal where the dents are. The dents will appear as below: a circular area of light with a little dark ring around it. This is visible below: we see an area of round light with a little ring of darkness. In this case the dent is obvious, but that light pattern observation I mention is nice for finding the small dents.


Third, I flip the fender over and use the round side of the hammer head to pound out the dent. I place the fender into the form and strike the center of the dent. The force of the strike varies based on the depth of the dent. I may have to put a couple more blows in to finish out the dent after getting the center worked. As you can see below, the dent is now gone, though an area of paint loss is present. Something must bumped the bike, causing the dent and paint scrape. Now that the dent is gone, I can come back later and cosmetically fix the paint loss.




Next, I do the rear fender. These fenders are the same contour, and the method is the same.




Fourth, I find areas along the sides of the fenders that need help. Sometimes an object strikes the fender from the side, causing the edge to be curled inward. The fix on the New World fenders is devilishly simple- use your hands. That's right, the fender metal is just mild steel sheet, and if you have good, strong hands and a feel for the metal, you can just thumb the edge back into shape.



Fifth, if I needed to reshape the fender tips due to metal loss, I'd do that as well. These fenders do not appear to need it. However, I did tip shaping and grinding on the Raleigh Dawn Tourist project, which can be seen here:

Shaping And Griding Fender Tips: October 2012

The results are not bad at all- the fenders are re-shaped and now ready for cosmetic work on the braces and paint.






Also:

I took the opportunity to clean up the chainguard- a Schwinn feather type. The decal has lost some condition, but it's still pretty nice for original condition.








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