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Post by triitout on Dec 17, 2014 18:16:12 GMT
Now that I've put 105 lb pressure into my new Panaracer Pasella tires, they've popped off the rims of the original Birmalux clincher wheels on my GP porteur several times. I guess I'll just inflate to 85 lbs like the old IRC tires that came with it and risk a pinch flat instead. Anyone else have that problem? My LBS said the height and design of the rims was the problem. Luckily this didn't happen out on the road like the death pedal!
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Post by vtchuck on Dec 17, 2014 22:47:36 GMT
You need a high pressure "hooked" rim like Super Champion Gentleman, Rigida 1319 or Mavic Module E. I'm rebuilding my wheels with Viscount hubs and Module E 27" rims so I
can use the 27" x 1" Pasellas.
Also, if you're using older, "non-hooked" rims, be sure to use a tire with a metal wire bead.
Cheers!
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bendo
Viscount
Posts: 538 
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Post by bendo on Dec 18, 2014 8:43:15 GMT
Another tip is to use a 700C tube. They're available in more width variations than 27". The slightly smaller tube tends to let the tyre sit a bit lower than usual. Dunno if this will help to stop it blowing off the rim but it does seem to create a lower profile set up. The tubes available in 700c ar also better quality. b
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Post by triitout on Dec 18, 2014 13:18:09 GMT
Thanks for the trouble shooting ideas b and vtchuck. I've already been using 700c tubes and the Pasella's are wire bead. The old IRC tires were never a problem so intuitively, I'm thinking the only difference is the air pressure. Will give it a try at 85 lbs over the weekend and keep my fingers crossed. Geez, between the pedals and the tires, why is such a nice bike giving me such issues???!!!
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Post by cusqueno on Dec 18, 2014 13:24:33 GMT
Another tip is to use a 700C tube. They're available in more width variations than 27". The slightly smaller tube tends to let the tyre sit a bit lower than usual. Dunno if this will help to stop it blowing off the rim but it does seem to create a lower profile set up. The tubes available in 700c ar also better quality. b Seems a good plan, although I thought all 700c tubes were also for 27". Can't recall seeing one branded as just 27". The difference in circumference - around 24mm in about 2000mm - is really neither here nor there when you are dealing with rubber. |
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Post by cusqueno on Dec 18, 2014 13:50:10 GMT
From the Harris Cyclery (Sheldon Brown) website: "Traditional 630 mm (27 inch) rims were straight side design, but in the late '70s they evolved to a "hook edge" design which would permit the use of higher pressures. "These days, many 630 mm (27 inch) tires are marked "For hook edge rims only" "The fact is that modern 630 mm (27 inch) tires will work on older straight-side rims, but they won't handle as much pressure as they are capable of with hook edge rims. "Generally, the "rule of thumb" for traditional 630 mm (27 inch) tires is that they should be inflated to 70-75 psi. This shouldn't be a problem with any tire, despite whatever disclaimer the manufacturer puts on the sidewall. However, if you're restricted to this pressure range, you probably shouldn't be running tires narrower than 1 1/8, or preferably 1 1/4, unless you're a very lightweight rider." This suggests that 85psi is near or just over the limit for a non-hooked rim. |
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Post by vtchuck on Dec 18, 2014 14:11:33 GMT
You also might try other tires.... Kenda makes a gumwall with a 90psi max pressure.
I like Gatorskins.... Expensive, but worth it.
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Post by triitout on Dec 18, 2014 15:07:52 GMT
Good info from Sheldon Brown of course! I think that validates just running the Pasellas at 80-85lbs just like the old IRC stock. I'm good at 27 x 1 1/8. This bike is a casual low speed rider so it may take a while to wear out these tires before I make a switch and who needs rock hard high pressure inflation? Hopefully it will stay warm enough for some test rides but for now, I'll call it problem solved.
Cheers,
Michael
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rmw
Viscount
Posts: 143 
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Post by rmw on Feb 2, 2015 22:24:27 GMT
Go with the lower pressure. Chris Juden of CTC says much the same.
We had the same problem with husband's old Raleigh. I got him lovely new Panaracer tyres and pumped them up. They blew and they blew and they blew. I have a big bag of exploded inner tubes (might come in useful...)
No problems since I stopped pumping them so hard.
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Post by triitout on Feb 3, 2015 3:16:05 GMT
Go with the lower pressure. Chris Juden of CTC says much the same. We had the same problem with husband's old Raleigh. I got him lovely new Panaracer tyres and pumped them up. They blew and they blew and they blew. I have a big bag of exploded inner tubes (might come in useful...) No problems since I stopped pumping them so hard. Yes, that's exactly what I've done. The old rims are handling new wire bead Pacelas at 80-85 lbs pressure with no problem just like the old IRC's! No blowoffs since. I guess it's the same principle as the chain being as strong as the weakest link! Cheers, Michael |
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