on 4/20/10 4:36 AM, Thomas Lynn Skean at thomaslynnsk...@comcast.net wrote:
> Question: a couple folks indicated that the 35mm @60 psi combination > was too low a pressure. Was that intended to suggest that higher > pressure would help avoid my wheel problems? That seems counter- > intuitive. I was just a bit suprised that you were having such significant wheel issues without pinch flatting. It struck me that while 60 psi may be giving you a smooth ride, the volume might be sub-optimal for your weight and distribution percentage. My own arrival at appropriate pressure is very subjective and reasonably personal - it's only recently that I came across Jan's publishing of the "15%" sag findings. Spreadsheet in xls format here - http://groups.google.com/group/rbw-owners-bunch/files?&sort=date Basically, for my trails and riding style, if the bike is bouncing, I back off the pressure until the tires just barely deflect on the hardest, nastiest edges that I hit at normal speeds. Then I sort of forget about it until they lose enough air that I feel them really compress on rocky edges. The worst wheel damage I've caused recently was courtesy of inattention, followed by sliding about a couple feet sideways down an embankment onto a paved roadway. Lots of side load and I hit the saddle hard as the bike hit pavement. Didn't pinch flat, but ganked the rim. This was _after_ smacking it back straightish... http://www.flickr.com/photos/cyclofiend/2643604057/ The hub was fine, and the spokes were reused to a new rim. Which is sort of the way I'd expect failures to occur - tire/tube before rim before spoke before hub. Back in freewheel mtb days, I used to bend a goodly number of axles, but haven't in a while. > > Also, the "max" pressure on these tires is either 70 or 80 psi. While > the value of that figure as an absolute max is questionable, it > suggests to me that using 60psi is not all that unexpected. If the > suggestion is that I'm subject to pinch flats... well, to date all of > my flats have been due to either my ham-handedness changing a tire or > a Pasela sidewall failures (4 of those within 2000 miles). None have > been pinch flats or even road-hazard flats. And I've had no other tire > fail at all, so I think the Pasela failures are Panaracer's failures, > not mine. Of course, YMMV. Hmmm... such spoke/failures (particularly without any pinch flatting) would point me back to looking at the dropout alignment or rear triangle alignment on the frame. You can get a sense of frame alignment with the string test described on Sheldon's site: http://www.sheldonbrown.com/frame-spacing.html You are running the right hubs for your frame spacing, right? - Jim -- Jim Edgar cyclofi...@earthlink.net Cyclofiend Bicycle Photo Galleries - http://www.cyclofiend.com Current Classics - Cross Bikes Singlespeed - Working Bikes Get your photos posted: http://www.cyclofiend.com/guidelines "Then I sat up, wiped the water out of my eyes, and looked at my bike, and just like that I knew it was dead" -- Robert McCammon, "Boy's Life" -- 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.
