Heresy or smart move?
 

I took a test drive of my Raleigh Ltd. 3 yesterday. At first, everything was fine. Then I tried to shift the SA 3-spd. hub and the cable broke at the chain linkage. Okay, so I'll cruise along in high gear. So Far, so good, just bebopping along then BAM! the rear wheel has a blowout. Dogs barking, children crying, ears bleeding. Dang! That was LOUD!

Well, I did overinflate the wheel a bit. And the tube wasn't exactly a 26 x 1 3/8. But once I got home and inspected the wheel, I noticed a couple of dings in the rim. So what was the cause of the blowout?

I've ordered a bona fide replacement tube and promised not to overinflate the tire again but I got to thinking that if it blew out again I was going to replace the rims.

I've got one choice for 650A rims and while considering this I got to thinking about how much praise has been heaped upon the 650B, a similar wheel that's just a teensy bit smaller. Both wheels are kinda rare, both normally run wider than the average road wheel. This website seems to think 650B is the cat's meow.

So, what do you think I should do?

Perhaps you should remove the dents from the rim before you mount your next tire/tube (LBS will most likely be glad to do that). The dents may prevent the bead from catching the hook securely.

I'm not sure of the availability of 650 A or B tires.

When you say "TEST DRIVE" do you mean that this was a ... P.O.S. bike you had found in the trash? ... Bike you had not before ridden? ... New purchase? ... New wheel? ... New tire? ... New tube?

One first considerstion: There were TWO different and completely incompatible rims and tires which were BOTH called 26 x 1-3/8"

1.) Raleighs and most British 3-speed bikes used an "EA.3" rim for a 26 x 1-3/8" tire which had a bead diameter of 590. [ISO: 37x590]

2.) Schwinn 3-speeds bikes used their "S-6" size rim for their totally different size tire they ALSO called a 26 x 1-3/8" which had a bead diameter of 597 [ISO: 37x597]

Put the minutely larger size tire on the smaller rim, inflate it well, and it might ride briefly until one little section of tire slips out of the rim, and BAM! I've had this happen even with the correct sized modern road tires which simply had not seated quite right into a perfectly correct rim. To compound matters, those older rims often did not have nice things like modern "hook edged" rims which help to hold the bead of the tire from slipping off. If the tire were old and neglected, a section of the sidewalls could have weakened to allow the tire to bulge out at one spot, and the bead itself could even have separated or loosened from the sidewall. I suppose a ding on the edge where the tire and rim meet might give enough variance to release a section of tire too. And then over-inflating a tire could possibly push apart the sides enough to help the tire jump the rim.

I would carefully check that the tire and rim are a suitable match. Then, carefully examine the tire for any wear or damage - especially after a blow-out. Then, after replacing the tube, inflate it slowly, in stages, and keep checking that it is staying on the rim on both sides and all around. ... Then pray.

Original 1972 steel rims, small dings are on the outside sidewalls. They aren't visible on the inside of the rim. New Kenda 26" x 1 3/8 tire(37 - 590), tube was a Specialized 26 x 1.25/1.5

I am thinking I just overinflated the tire; I had it over 80psi and the tire wall says max is 55psi. Oops.

These rims do not have "hook edges". LBS said it was very important to seat the tube and tire correctly and to SLOWLY air the thing up.

Since I ride my bikes pretty hard, I may be getting some new wheels for Christmas. The wheels and tires and tubes are readily available online; I would like some feedback from others who've ridden the 650A's and B's.

80 psi in tires marked for 55 psi is asking for trouble...

80 psi on non-hooked rims is a BIG problem!!!!

Both is a recipe for a blowout.

I agree with the theory that you overinflated it.I won't go much higher than 60 PSI with the 26x1 3/8 tires.You should be good to go.You just have to fix the shifter cable.I bet it was rolling really nicely at 80:)

This is why we use pressure gauges.

Even a radially belted car tire will blow out from being over pressure. Get that over pressure tire moving, and the air inside heats up. That means the pressure goes up even more. Sooner or later, boom. Usually sooner. A bike tire is lighter, thinner, and does not have strips of steel embedded in it. They won't take the abuse that a car's tires will.