Tire psi question

[Sandy]

I have a tire psi question. As some of you know, I have started to use 700x25 Michelin Pro2 Race tires. 93lengedti had commented that his MichelinPro2 Race tires bounced and hence he took them off and started to use Continental GP4000 tires. I noticed that my Michelin tires also bounced (I could see my front tire bounce) which I found that to be very disconcerting. I was using 92 psi front and 102 psi rear. I thought about lowering the psi, but a very knowledgeable cyclist suggested that I raise the psi, which I did. He thought the tires might be compressing, causing the problem. So I raised the front psi by 5 pounds and the problem remained. Someone else suggested that I should lower and not raise the psi.

I took off the Michelin tires and tried some new 700x23 tires that I had. Presto, the bouncing was gone.

My head is about to burst from the immense pressure of trying to decide what to do.

Any reasonable suggestions? I have an idea that I am going to get some weird suggestions here (mostly about me).

Thanks for any comments (I think).

Full of hot air,


:) Sandy :)

[scrooge]

I'm slow--could you explain more what you mean by "bounced"
I've been trying the same tires at the same psi and have noticed that I tend to send rocks flying more often (it seems) and that if I hit something on the road (a rock or a stick) I, well, "bounce" off of it (maybe I do know what you're talking about). I was also wondering if that was coincedence or related to the tire. On the other hand, they also feel a little "squishy" to me some times. But I think they are more comfortable than the conti's I was riding...
So I guess I can't answer your question, but I'm curious to hear what the sages say.

[dbrk]

As I see it people will get used to whatever they take the time to get used to. Ride race bikes only, you like race bikes. Ride thisorthat you like this and that. So it goes. This goes for tires, bike designs and geos, materials, or aesthetics. Having gone fat tire (25mm or above), I'll never go back (except once in awhile...I mean my Pegorettis can only take a 25mm Vittoria and for the pleasure of riding those bikes on smooooth roads, that's fine. But never anymore 23s. It's just too narrow, stiff, and not as much fun for _me_.). But there are lots of ways to experience bicycles and not all of them are even remotely the same.

dbrk

[Sandy]

Thanks for the comments. Drop a tennis ball on the ground and it bounces. That is the type of "bouncing" that I mean but obviously on a much smaller scale. It looks like the front tire is bouncing when the bike goes over a little rut in the road; as if the tire does not stay fully adhered to the road surface and his moving up vertically.

Look at what is happening in this picture- First part of the sequence: :bike:


Bouncing off the rubber walls in my room,


:bike: Serotta Sandy :bike:

[93legendti]

I...93lengedti had commented that his MichelinPro2 Race tires bounced and hence he took them off and started to use Continental GP4000 tires...:) Sandy :)

I thought I said they were the older Michelin's and I switched to GP3000's...just settin' the record straight. :)

[Too Tall]

Snandy - I'll take the 25's, my tandem needs some skins babe...seriously send em'.

[CalfeeFly]

Try running them at the suggested max psi which I believe is 110. See if they still bounce. If they do...blame it on Kevan...mail them to Too Tall...go back to 23's and forget the experiment...I did...

[Bill Bove]

What psi are you running? Generelly as a tire gets wider it will require less pressure to achieve top performance. I run my 23's at 115/120 for fast rides and the 25's on my training bike at 100/105. Try dropping the psi. Sometimes the simple solution actually works.

[palincss]

I have a tire psi question. As some of you know, I have started to use 700x25 Michelin Pro2 Race tires. 93lengedti had commented that his MichelinPro2 Race tires bounced and hence he took them off and started to use Continental GP4000 tires. I noticed that my Michelin tires also bounced (I could see my front tire bounce) which I found that to be very disconcerting. I was using 92 psi front and 102 psi rear. I thought about lowering the psi, but a very knowledgeable cyclist suggested that I raise the psi, which I did. He thought the tires might be compressing, causing the problem. So I raised the front psi by 5 pounds and the problem remained. Someone else suggested that I should lower and not raise the psi.

I took off the Michelin tires and tried some new 700x23 tires that I had. Presto, the bouncing was gone.

My head is about to burst from the immense pressure of trying to decide what to do.

Any reasonable suggestions?



Your bouncing might very well have been caused by too much tire pressure. I can't see how it could possibly have been caused by too little pressure. It would have made a lot of sense to try lower pressure before removing the tires - you would have lost nothing, since if you weren't happy you could have simply continued deflating the tires, etc. as you went on to replace them.

However, now that you have switched to 23s and are happy, or at least, I presume you are happy, I would think the smart thing to do is keep riding them until you wear them out.

At that point, before you buy new tires, you might again try the 25s, this time at lower pressure.

Or, you might consider trading with someone for more 23s.

Or, if you feel in need of some upper body workout, hand strengthening, and hand dirtying, you could always remove the 23s, put the 25s back on with less pressure, etc., but I have yet to meet anyone who would be willing to go through the hassle of R&Ring tires just for the sake of curiosity...

[BarryG]

Sandy, I'll seriously trade you Mich Pro Race2 700X23's for your 25's. PM if you're interested.

[Ken Robb]

When I inflate my tires (car, bike, motorcycle) close to max pressure they all bounce more/stick less.

Tires are meant to have a little flex in the sidewall to cushion the ride and let them deform slightly and conform to irregularities in the paving or dirt. This is why they are better than solid rubber tires.

How much pressure is correct depends on the load they must support and the volume (size) of the tire. Generally more weight or smaller volume requires more pressure. Too little pressure can cause snake bite flats and squirmy, mushy handling.

I run 110psi in my 700x23 GP 3000.
95psi 700x28 Conti Ultragatorskins
95psi 700x27 RuffyTuffy
85psi 700x32 (really 29mm) Pasela
I weigh about 200lbs nekkid and don't carry more than 10lbs of cargo most of the time.

[93legendti]

I am using 95-100 psi (depends upon the pump!) on 23's--but I am closer to 150lbs than I am to 200lbs.