Wide clinchers, narrow tires, and pinch flats

[shovelhd]

My road training wheels are 27mm wide at the brake track. I am currently using GP4000s 23mm tires which measure 24mm inflated. Tire pressure is 95/90 and I currently weigh around 150 pounds. For the last three weeks I have had pinch flats from hitting potholes or road cracks very hard. I am going to experiment with tire pressure, but should I really be using 25mm tires?

[eddief]

ride with A23 rims, 25c tires, inflated to 80 psi. try not to hit big potholes, but have not had a pinch flat in years.

[p nut]

...I have had pinch flats from hitting potholes or road cracks very hard...

Although going to 25's may add a little more buffer between the road and rim, I don't think it will alleviate your problems if you keep hitting potholes "very hard."

[jtakeda]

I've got A23s with veloflex 22s. Haven't pinch flatted them yet on Bay Area roads.

Same weight and pressure

[jr59]

don't hit potholes! :cool:

[kramnnim]

Hmm, guess I'm not the only one. Same tires, less psi, lighter, wide rims, pinchflats hitting potholes not pointed out.

[SBash]

I agree with eddief. 23mm rims with 25c tires at approximate 80psi very cush, great handling and no pinch flats....I am approx. 200lbs.

[bluesea]

I agree with eddief. 23mm rims with 25c tires at approximate 80psi very cush, great handling and no pinch flats....I am approx. 200lbs.


I'm running about 170lb, and for me with Archetypes/25mm 4000S, 80psi is too low. Almost sounds like climbing on hardtop with MTB tires at off-road pressure. I run 95PSI (rear) with that setup.

[Cicli]

I am in the camp that believes everyone should be on at least 25's. That said, I am 165 and run 25 Veloflexes at 80 psi. I hit everything. No pinch flats in years.

[SBash]

I'm running about 170lb, and for me with Archetypes/25mm 4000S, 80psi is too low. Almost sounds like climbing on hardtop with MTB tires at off-road pressure. I run 95PSI (rear) with that setup.

But are you using 23mm rims like A23 or Pacenti's? IMO, handling and descending is better and climbing the same. You still have more air volume vs 19mm rims.

[pbarry]

My road training wheels are 27mm wide at the brake track. I am currently using GP4000s 23mm tires which measure 24mm inflated. Tire pressure is 95/90 and I currently weigh around 150 pounds. For the last three weeks I have had pinch flats from hitting potholes or road cracks very hard. I am going to experiment with tire pressure, but should I really be using 25mm tires?

You might be at the tipping point of rim width vs tire width. Most seem to have good luck with 23 wide rims and tires that size or wider. The 27 rim width would stretch the beads further apart, and the tread would end up closer to the rim than with a narrower hoop. 25s would be a good place to start. JMO

[shovelhd]

Believe me, I don't aim for them. The roads worth riding around here have issues, and in a paceline you can get caught hitting something unavoidable. I used the same tires on 21mm rims and I never, I mean never, had a pinch flat. Plenty of wires, nails, screws, tacks and other pointy things but I hit the same kinds of holes and cracks and had no problems. I ran them at 105/100. This is why I am asking the question.

[shovelhd]

You might be at the tipping point of rim width vs tire width. Most seem to have good luck with 23 wide rims and tires that size or wider. The 27 rim width would stretch the beads further apart, and the tread would end up closer to the rim than with a narrower hoop. 25s would be a good place to start. JMO

Thanks for your input.

[Ralph]

You might be at the tipping point of rim width vs tire width. Most seem to have good luck with 23 wide rims and tires that size or wider. The 27 rim width would stretch the beads further apart, and the tread would end up closer to the rim than with a narrower hoop. 25s would be a good place to start. JMO

I agree. 25's or even slightly wider. Not all 25's will even mearure 25, and not all 28's measure 28.

Although I mostly still ride narrower clincher rins and 23's. All roads smooth around here. No need for fat tires. But would match the tire with the rim.

[merckx]

My road training wheels are 27mm wide at the brake track. I am currently using GP4000s 23mm tires which measure 24mm inflated. Tire pressure is 95/90 and I currently weigh around 150 pounds. For the last three weeks I have had pinch flats from hitting potholes or road cracks very hard. I am going to experiment with tire pressure, but should I really be using 25mm tires?

I'll bet you received many of those pinch flats on Pine Street although it appears to be resolved now.

[lhuerta]

What is the actual bead to bead distance / inside width of your rim? 27mm at the brake track means nothing....the so called "wide rim" effect is based on the actual bead-to-bead distance/inside width. Unless you are running a rim with 17mm or wider indie width your not going to experience the wide rim effect. More importantly, what is your weight? If your rims are indeed wide at the inner width, I wouldn't go more then 10 psi less then recommended pressure. Here is a good primer:http://fairwheelbikes.com/c/forums/topic/2013-rim-roundup/

[shovelhd]

What is the actual bead to bead distance / inside width of your rim? 27mm at the brake track means nothing....the so called "wide rim" effect is based on the actual bead-to-bead distance/inside width. Unless you are running a rim with 17mm or wider indie width your not going to experience the wide rim effect. More importantly, what is your weight? If your rims are indeed wide at the inner width, I wouldn't go more then 10 psi less then recommended pressure. Here is a good primer:http://fairwheelbikes.com/c/forums/topic/2013-rim-roundup/

Bead-to-bead distance is 23mm. Weight as stated before is currently 150 pounds, race weight is 145 pounds.

[AustinHorse]

Based on personal experience yes, too wide of rims are absolutely doing that. 25s, as most people are saying, are fine for 23s, but 27 is pushing it.

[jr59]

Believe me, I don't aim for them. The roads worth riding around here have issues, and in a paceline you can get caught hitting something unavoidable. I used the same tires on 21mm rims and I never, I mean never, had a pinch flat. Plenty of wires, nails, screws, tacks and other pointy things but I hit the same kinds of holes and cracks and had no problems. I ran them at 105/100. This is why I am asking the question.

I meant that as a joke. Sorry no offence meant. Just trying to get a smile out of you.

I have zero clue how to help your problem here. But I wish you the best of luck

[Tandem Rider]

Seems to me that GP4000's are a pretty light tire for winter, and 23 sounds pretty skinny for bad roads to boot. I am about 5 pound heavier than you, and I run 28's either in Gatorskins or Armadillo's, whatever is cheaper that day. I absolutely HATE freezing to death while fixing a flat in the winter.

Pinch flats are almost always caused by getting the pressure/volume/weight mix wrong. Have you verified your gauge hasn't gone "wonky"?

[shovelhd]

I meant that as a joke. Sorry no offence meant. Just trying to get a smile out of you.

I have zero clue how to help your problem here. But I wish you the best of luck

I thought you were serious, but no offense was taken. No worries.

You'd think with all the time I've spent riding that this would be a no brainer but this wide rim stuff is all new to me.

I will experiment with pressure. My guess is that it's about 8-10 pounds too low. I tried this before and the ride suffered.

[shovelhd]

Seems to me that GP4000's are a pretty light tire for winter, and 23 sounds pretty skinny for bad roads to boot. I am about 5 pound heavier than you, and I run 28's either in Gatorskins or Armadillo's, whatever is cheaper that day. I absolutely HATE freezing to death while fixing a flat in the winter.

Pinch flats are almost always caused by getting the pressure/volume/weight mix wrong. Have you verified your gauge hasn't gone "wonky"?

I will definitely try the 25's. I have been using my SKS gauge to check pressure.

[jr59]

I thought you were serious, but no offense was taken. No worries.

You'd think with all the time I've spent riding that this would be a no brainer but this wide rim stuff is all new to me.

I will experiment with pressure. My guess is that it's about 8-10 pounds too low. I tried this before and the ride suffered.


Does the ride suffer more than having to stop, in the cold, while the group motors ahead, and fix a flat?

What ever it is, I hope you get it all worked out!

[oldpotatoe]

My road training wheels are 27mm wide at the brake track. I am currently using GP4000s 23mm tires which measure 24mm inflated. Tire pressure is 95/90 and I currently weigh around 150 pounds. For the last three weeks I have had pinch flats from hitting potholes or road cracks very hard. I am going to experiment with tire pressure, but should I really be using 25mm tires?

I'm surprised you can even get a 23mm tire to seat on such a wide rim. Yes, get 25 or 28 if they fit your frame..no payback.

[giverdada]

i love 25s, and i don't weigh too much more than you. 25 on my archetypes and A23s are gorgeous, and supple, and fine for not flatting. all my flats lately have been full-on punctures, no snakebites.

and despite the thought that your rims are likely too wide for the tires you're running, i think it has more to do with circumstance of your riding than not. you're likely hammering everyone in the paceline, so they wait for a good hole to come up, point it out to everyone but you, and then you flat and they get an easier go of it!:no:

ok, maybe it's just the tire width...:)

[HillDancer]

...I am going to experiment with tire pressure, but should I really be using 25mm tires?
If you have clearance, I would use a 25mm tire like Michelins that run wider than nominal when mounted, or a 27-28mm nominal width tire. You have decent internal rim width for a skinny tire bike, take advantage of it.

You might be at the tipping point of rim width vs tire width. Most seem to have good luck with 23 wide rims and tires that size or wider. The 27 rim width would stretch the beads further apart, and the tread would end up closer to the rim than with a narrower hoop. 25s would be a good place to start. JMO
A tire's circumference/diameter is determined and constrained by its cords. Due to the diagonal weave if most bicycle tires, there is a very minor change in tire diameter when increasing internal rim width. Theoretical models calculate the difference maxing out at less than 2mm for outside diameter/circumference. As long as BCD is constant, a user wouldn't see a different measurement when rolling-out rim & tire in a comparison, because the difference is so small.

In a tubed tire on hooked rim, a pinch flat occurs when the tube is excessively compressed between the tire wall(s). Moving the bead hook outward reduces the likelihood the tire wall will fold around the tube.

I don't think the rim is too wide, but I do believe the tire has too little volume for poor surfaced roads.

[shovelhd]

The frame will fit 25's. That's the next step. Thanks for the help.

[Hindmost]

My guess is that it's about 8-10 pounds too low. I tried this before and the ride suffered.

I have ridden the same 23's for some time now, pressures somewhere between 90 and 110. I don't think I could lower the pressures to make a more cush ride; they ride a little firm.

[shovelhd]

I have ridden the same 23's for some time now, pressures somewhere between 90 and 110. I don't think I could lower the pressures to make a more cush ride; they ride a little firm.

On wide rims? 90-110 is a rather large variance.

[Hindmost]

I can't speak to narrow vs. wide rims. I agree with your assessment to increase pressure to avoid bottoming on the rims. I think 23's provide less ride quality and cushion trade-offs than that of larger tires.

Over the years I have tried various pressures and I am not terribly fastidious in airing up my tires.

[buldogge]

I can never get over the low pressures some of you guys run.

I run 180-185# and run 25mm tires @ 105F and 110R…mainly Veloflex Master/Corsa, Vittoria CX, Schwalbe ZX, or Michelin Pro4.

FWIW...23mm tires at 110/115 and 28mm tires at 95/100 as well.

I pretty much never pinch flat (off of gravel) on road tires and, frankly, riding at lower pressures feels like dragging the bike down the street…IMHO.

Also, these are on both "narrow" and 23mm rims.

-Mark in St. Louis

[shovelhd]

I have some initial feedback on the 25's on 23mm internal width rims. The ride quality is better than the 23's at the same pressure. I didn't hit anything so time will tell with the durability. Thanks to everyone for their input.

[CiclistiCliff]

Tire should not be narrower than outer width of tire.

[p nut]

Tire should not be narrower than outer width of tire.

Que?

[shovelhd]

He means rim. Not narrower than the width of the rim. Aero weenies would disagree with him. That's not why I ran 23's though, it's because I already had them and didn't feel the need to buy 25's until I flatted three weekends in a row.

[CiclistiCliff]

He means rim.

yeah. that. :help: