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What's the minimum PSI I can run?(9 posts)

What's the minimum PSI I can run?Matno
Jan 23, 2003 9:39 AM
I've been trying everything I can to smooth my ride out, and short of buying new tires (my next step) I'm wondering if I can lower the tire pressure? I have 28mm Conti GrandSports (the 28mm alone ought to do something, but it doesn't!). They say max inflation of 120psi, but no mention of a minimum. I'm only 140lbs myself, but I don't want to ding my rims on a crack in the sidewalk! How low can I safely go?

One of these days I'll be able to afford a new frame. Anyone interested in buying a classic Schwinn Supersport frame?... :^)
re: What's the minimum PSI I can run?KEN2
Jan 23, 2003 9:46 AM
I haven't ridden that particular tire, but other 28s I have run at 75-80 psi on the road with no pinch flats (and I weigh 190).

BTW under what circumstances are you riding on sidewalks? It's generally illegal to ride a bike on the sidewalk, besides being dangerous to mix it up with unpredictable pedestrians...
Sorry, not sidewalks. Bike paths...Matno
Jan 23, 2003 2:27 PM
I was just trying to describe conditions simply. I don't ride on sidewalks! :^) (Besides, here in the Bronx there are too many cars parked on the sidewalks to ride there anyway!)

I'll try lower pressure and see if it helps...
I'd say 90-100 psiMcAndrus
Jan 23, 2003 10:28 AM
Some folks like 'em softer than this. I've never ridden 28s but I used to ride 25s in my touring days a few years back. I'd inflate them at around 100psi. If you go too low you'll get pinch flats. I would think if you inflated any tire to 120 and you weigh 140 you'd get a rough ride.

I'd think 100 would be a good compromise for comfort and flat-resistance.
28mm on my touring bikeKeeponTrekkin
Jan 23, 2003 10:44 AM
I have 28 mm on my touring bike and they have a maximum inflation of 90 psi. (Knock on wood) I've never had a flat with those tires on the road with pressures in the 80 - 90 range. I weigh 178 and it's a heavy steel bike with racks, fenders and lights.

Your weight on 28's could go 80-90psi no prob...nmrwbadley
Jan 23, 2003 11:29 AM
I weigh 225 and can go to >90 psi on smooth pavementcory
Jan 23, 2003 12:27 PM
If you have room, I'd say to try bigger tires. I've been using 700x35s on my Atlantis for a year, and really like them.
At 140 pounds, though, you could go pretty low on pressure. Certainly you don't need anywhere near 120psi. When I run 28mm tires, I keep them at 90-95 with no trouble at all. On gravel roads, I can let the 35s down into the high 60s. Just don't hit any curbs.
I wish...Matno
Jan 23, 2003 2:27 PM
Well sort of anyway. I have absolutely no more clearance right now. About 1.5mm between tire and frame! However, since I am also interested in keeping weight to a minimum, 35's are probably out of the question.

Problem is, the roads around here are so rough, it's like hitting curbs all the time. Of course, I try to ease up and down the bumps, but there's always the occasional jolt...
120? Wowsers.jw25
Jan 24, 2003 8:04 AM
I'm running some 25mm Axial Pros, and their max inflation is 95 psi. I weigh 145, and I'm happy running them at 85, with no pinches or dings. Just wish my frame had more clearance, as I've got maybe 3mm to each side, and 5mm to the seattube.
For 28's, I bet you could go down to 90 psi. The GrandSports are a burly training tire, so they shouldhave more rubber and more casing plies, both of which mean you can run lower pressures.
I'd say try dropping pressure until the ride gets squirrelly or you go below 85 psi, whichever comes first. I bet the 120 limit is for loaded touring or tandems, both of which would put them under a much greater load. Us skinny people can get away with more - a woman I used to train with would just run whatever her tires were at for training, and once did a 45 mile loop at 55 psi (in 23mm's). She's probably 100 lbs, but you should have seen how much flex her tires had.
I'd also recommend a new saddle (Prolink gel or similar) or a suspension seatpost. Either or both will smooth the ride quite a bit.