This certainly does sound like a pinched tube. What do the holes look like? A pinch produces two small holes that look like a snake bite. If this is the case, after mounting the tube go around each side of the rim pushing the tire in and make sure you can see the rim. Then run a lever around between the rim and tube. Put about twenty pounds in and inspect the rim - tire connection. If it's OK add another 20 lbs and repeat.
Since you have swapped wheels it don't sound like a rim defect. Also, from your note it sounds like it is only the rear. Have you considered swapping the tires? Also, I always mount the label next to the stem so I can more easily find a relationship between the tube and something embedded in the tire. Keep us posted. Michael On Sunday, March 9, 2014 1:19:06 PM UTC-4, Nick Worthington wrote: > > Querying the collective knowledge here. We're having a recurring problem > with the rear tire on my wife's Betty blowing out at around 60 PSI and > above. Schwalbe Little Big Ben, which is rated for 50-85 PSI. Yesterday, > it blew two blocks from home, after being topped up with air, ithad been > ridden with no problem for several months since the last blowout. Thought > it might be rim tape, so we actually swapped the whole wheel, since we had > a spare. Still happens. Once, it blew just after inflation, in our hands, > when we were replacing the tube from a prior blow out. I'm thinking it > must be the tire itself, but I don't see anything obvious - Maybe a > slightly rough patch near the bead, but it doesn't seem to have any obvious > pointy bits.... > > Thoughts? > > Nick W. > > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
