David: I once had a Velocity rim that developed a solid thump with each revolution upon braking. I tried everything to deal with it - changed the pads, lightly sanding the rims - all of the standard stuff. Finally, on a big down hill, the braking surface of the rim separated. When I inspected the rim further, I discovered that the rim had also cracked internally, right along the spoke holes, for about two centimeters. I'm certain that was cause of the thumping - the rim was wider where it had cracked. Later, Velocity admitted that there was a manufacturing defect in several rims purchased around the time when I bought mine.
Here's what you might do: Mark the rim where you are getting the thump. Take the tire, tube and rim strip off and inspect the center channel of the rim at that spot. Also, inspect the area around the spoke holes inside and out for cracking. I also have to wonder whether the spokes have too much tension. It is not normal to have an "unpleasant thump" with each revolution as you brake. Something is causing it. In this case, I really don't believe that a change of pads will cure it. I'd be interested in the outcome. Keep us posted. Dave On Aug 13, 7:53 pm, "carnerda...@bellsouth.net" <carnerda...@bellsouth.net> wrote: > My 650B Sam Hillborne has Velocity Synergy rims and Shimano Deore V- > brakes with the pads that came on them. Since new the front wheel has > had a little tick with each revolution while braking. I assumed this > was a slightly raised joint line that would flatten out with normal > wear. Over the last two weeks I have had three12-15 mile rides on > gravel and chip seal roads which include some steep sections with > multiple pot holes and required heavy braking. Between these rides I > had the usual short commutes to work. I noticed that braking in the > front had become much more uneven to the point that firm application > of the front brake caused an unpleasant "thump" with each revolution. > I decided it was time to clean the braking surface. When I did I > found the front rim to be fairly deeply scored and in a pattern where > the deepest scoring corresponds to each spoke hole. This is the same > on both sides of the rim. The rear rim does not have this pattern. I > have never seen this and can't find mention of it on the internets. > The links below are to pictures I took to try to show the pattern. > Am I doing something wrong to cause this? Should I change to > different brake pads? Should I be worried about > this?http://www.flickr.com/photos/carner/4889788162/in/set-72157623654420644http://www.flickr.com/photos/carner/4889790774/in/set-72157623654420644/http://www.flickr.com/photos/carner/4889196607/in/set-72157623654420644 > David -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
