High pressure tires on older rims
I've been runing vredestein fortezza se's on a set of older araya 7000 rims (rims were oem on a 91 Paramount and are in excellent condition).
The max. reccomended psi is 160 but I've been putting 140 in to stay on the safe side.
These are kevlar bead tires.
Last night,without warning(and the tires have been on the rims sence last september and done yoeman duty and I'd had the bike on a 35 mile club ride earlier in the day)the rear tire simply blew off the rim.
There was no apparent damage to the tire and I've checked the rims thuroughly
I'm wondering if maby 140 is too high a pressure for a rim built for tires of the time.
I go 220# and worry about running a 160psi tire at 110 or 120 lbs.
I'm assuming they are but just to check are those rims hook edge [bead] rims? (vs. straight sided on the inside).
On my older Araya hook-edge road rims, I've noticed the "hook edge" isn't as sharply angled as on other hook edge rims. All the Araya road rims I have are older than '91, so I don't know if this would be the case with your rims or not, but if it is I think it would make sense that they're probably not the best choice for extremely high pressure tires like you're running. If you have some other hook edge rims to compare them to, you might check and see if this is the case............As a side note, I've recently picked up some Mavic Module E rims, which I believe were the first hook edge clincher rims for high pressure road tires available, and they do have the very sharply angled, distinctinctive hook edge like you would see on the most modern rims today. And these Module E's are from the very early '80's I believe-
Last edited by well biked; 04-30-07 at 07:20 AM.
me have long head tube
Any high-quality clincher rim from 1991 (definitely anything that came on a Paramount) should be standard-modern "hook-edge". Are the tires really narrow? This makes them more likely to blow off the edge (whereas running 32mm-wide tires on narrow rims has other problems).
I'm pretty sure Schwinn offered a Waterford-built Paramount in '91, but they also offered several PDG (Paramount Design Group) "Paramounts" as well, which were not necessarily high end bikes. I don't mean any offense to the OP, and for all I know his Paramount is indeed a Waterford-built bike, but by '91 a Paramount didn't necessarily mean the same thing as in years past. Schwinn was near bankruptcy at that time and was milking the Paramount name for all it was worth..........I do agree that it seems unlikely that a '91 road rim wouldn't be a true hook edge rim, but I don't know, Arayas never struck me as particularly nice rims during that time period-
Originally Posted by timcupery
me have long head tube
news to me - and interesting. I don't know what the Araya 7000 is offhand...
How much wear on the rims? Can you feel any concavity on the brake surfaces?
It's nice that tire makers mold a max. pressure rateing on the tire, but half of the tire/rim interface is the rim. When rims are new, they are usually overbuilt to such a degree that they aren't a problem. As the brake surface wears, you have progressively less metal resisting the tire air pressure that's trying to push the rim flanges apart.
High Pres. tires on older rims followup
I stopped by the local shop this morning and checked a set of mavic open pro rims to the arays. The mavics definitely have a more pronounced shoulder (lip) inside.
Sence I'd previously been running Vittoria Rubino Pros with no problems (save being worn out at 3-4K)I'll probably go back to them.
I truly enjoyed the ride the vredesteins gave but I'm not about to build up a new set of wheels to accomidate high pressure tires.
BTW To the guy who asked; Yes this was the non waterford OS Paramount (built in Japan) I've upgraded over the years (stronglight compact crankset, 105sealed BB and Headset) but the 105 equipment has held up admirably over the years as have the wheels and with over 30K on the bike the frame still feels livly and offers a fantastic 100k ride mornings with the club.
Also: The guys at the shop checked the vredestein and found it to be a bit sloppy of a fit on the rim (when you can install and remove withoug the need for a lever......
What size tyres are you using? When I weighed 245#, I had 700x23c in front and 26c in rear using 120psi just fine. I would've preferred a 28mm tyre in the rear, but my chainstays aren't wide enough.