25C clinchers @ 110psi - too high?

[R332]

Am I too old school with my pressure habits? I weigh 82kg and ride 700x25C clinchers on 17.4mm (internal) rims at approx 105psi from and 110psi rear. I worry about pinch flats with lower pressure and the thought of lower pressure = faster just doesn't feel true out on the roads.

Am I beating myself up unnecessarily running this much pressure with 25Cs or are all the guys running ~80psi just softies wasting precious watts :confused:

[rePhil]

Try less and see how you like it. I weigh a bit less and like the ride ride with 80psi on my 25 Contis.

Am I too old school with my pressure habits? I weigh 82kg and ride 700x25C clinchers on 17.4mm (internal) rims at approx 105psi from and 110psi rear. I worry about pinch flats with lower pressure and the thought of lower pressure = faster just doesn't feel true out on the roads.

Am I beating myself up unnecessarily running this much pressure with 25Cs or are all the guys running ~80psi just softies wasting precious watts :confused:

[Llewellyn]

I'm around 77kg and have been running Conti GP4000's at 75R/65F and have been amazed at how much more comfortable it is compared to the 110psi I used to run. Try exeprimenting at a few combinations to see what works best for you.

[bikingshearer]

At the other end of the spectrum, I have a mass of 125 kg. (unlike pounds, kgs are a measure of mass, not weight. /pedantic pointless point) and run Conti 4000s at 120 psi. I am (very) large and hate pinch flats.

[bicycletricycle]

Pinch flats will depend some on road qualities.

I would say that is kinda high, not sure about the faster/slower thing but from a comfort perspective you could loose some pressure without too much danger of pinching.

Why not just try removing 5 pounds per ride till it starts to feel too slow or squishy or pinchy.

I usually just stop topping my tires up and keep riding the bike till it feels too low and then see what that pressure is and add 5 or 10 pounds.

[Neil]

I find that a rule of thumb with 25's is to run them around your weight in Kg.

Rear maybe a little more, front a little less- then go from there.

I'm 77Kg right now, running 80 F/R which I could probably reduce a little.

[eddief]

me 28 mm tires, 85 rear, 75 front, no pinch flats in years.

[cinema]

I find that a rule of thumb with 25's is to run them around your weight in Kg.

Rear maybe a little more, front a little less- then go from there.

I'm 77Kg right now, running 80 F/R which I could probably reduce a little.

psi similar to weight in kg sounds a little low but definitely ok. i am 61kg and run 28s at 75/80 to reduce rolling resistance and 65/70 ish when i'm just commuting. rim width is also a factor.

[Neil]

I'm on tubs currently, but I'd run clinchers (latex tubes, wide rims) at the same.

As ever, YMMV, I am not a Doctor, contents may settle in transit.

[dave thompson]

I'm 90kg, más o menos, and run 90psi front and rear in my 25mm tires.

[weisan]

>>I worry about pinch flats

Well, quit worryin'!
Watch where you are goin'.
:p

[Black Dog]

I worry about pinch flats with lower pressure and the thought of lower pressure = faster just doesn't feel true out on the roads.

Am I beating myself up unnecessarily running this much pressure with 25Cs or are all the guys running ~80psi just softies wasting precious watts :confused:

You are beating yourself up. Lower pressure is, in fact, faster. The test data does not lie. Our senses on the other hand can fool us. More feed back feels faster because we always get increased feed back at higher speeds at any preesure. Thus a tire at high pressure feels faster because it simulates the increased feedback that higher speeds produce. On an irrugular surface lower pressure is faster but "feels" slower because of the reduced feedback that the softer ride provides. The tire conforms to the irregularities rather than riding over them lifting you up against gravity and wasting more energy. Physics wins over psychology everytime.

[gasman]

At the other end of the spectrum, I have a mass of 125 kg. (unlike pounds, kgs are a measure of mass, not weight. /pedantic pointless point) and run Conti 4000s at 120 psi. I am (very) large and hate pinch flats.

Actually kg is the SI unit of mass. Newtons is one SI unit of force.

Pound can be a measure of force or mass. As in I weigh 170 pounds (mass) but run my tires at 100 pounds per square inch (force).

But I understand what you are saying. We don't use lbs in scientific measurements. Get rid of the Imperial system and get with rest of the world !

I play around with the pressure in my tires quite a bit. I'm about 170 and run 90f/95r but will go up or down depending on the tire.

[oldpotatoe]

Am I too old school with my pressure habits? I weigh 82kg and ride 700x25C clinchers on 17.4mm (internal) rims at approx 105psi from and 110psi rear. I worry about pinch flats with lower pressure and the thought of lower pressure = faster just doesn't feel true out on the roads.

Am I beating myself up unnecessarily running this much pressure with 25Cs or are all the guys running ~80psi just softies wasting precious watts :confused:

I am over .1 offa on(95KG) and with clinchers, 25mm Vittoria Pave, never have more than 95 psi front and rear and never get pinch flats.

[OldCrank]

what does the manufacturer of your tire say?

Michelin Pro4 25s (which are more like 26 or so right?) specify 73-109psi depending on rider weight. So you are in the range.

[Cicli]

what does the manufacturer of your tire say?

Michelin Pro4 25s (which are more like 26 or so right?) specify 73-109psi depending on rider weight. So you are in the range.

Manufacturer pressures are worthless. Sorry.
Vittoria recomends something huge. I cant recall what but its almost laughable.

Found it. This is what they recomend for a rider and bike at 190 lbs.

[berserk87]

I weigh about 95kg and started out on 25's running pressures around 110psi.

Having read a lot about lower pressures on wider tires, I took a leap of faith and lowered my pressures. I run anywhere from 80 to 95 psi now and the ride is more comfortable and I have had no issues with pinch flats. I can't tell any difference in speed.

[r_mutt]

what does the manufacturer of your tire say?

Michelin Pro4 25s (which are more like 26 or so right?) specify 73-109psi depending on rider weight. So you are in the range.


Michelin Pro 4 25's measure between 28-29. they are massive!

[Bstone]

I mass 72 kilos and run as low as 50/60, no pinch flats.

[enr1co]

Im 175 lbs and typically run 110 psi on 25mm tires. I don't care for squishy feel.

[R332]

UPDATE

The tires are Conti GP4000S II 25C and on my 17.4mm internal rims they measure over 27mm wide!

Today I lowered the pressure to 95F / 100R and rode 70 miles over mixed pavement types on a road loop I know very well. There is no doubt that the ride quality was more supple with less vibration transmitted and according to my Garmin I didn't go any slower :banana:

Next time I will try 90F / 95R because I still have a mental block with riding in the 80s ;)

[Cicli]

UPDATE

The tires are Conti GP4000S II 25C and on my 17.4mm internal rims they measure over 27mm wide!

Today I lowered the pressure to 95F / 100R and rode 70 miles over mixed pavement types on a road loop I know very well. There is no doubt that the ride quality was more supple with less vibration transmitted and according to my Garmin I didn't go any slower :banana:

Next time I will try 90F / 95R because I still have a mental block with riding in the 80s ;)

There you have it.

[Black Dog]

UPDATE

The tires are Conti GP4000S II 25C and on my 17.4mm internal rims they measure over 27mm wide!

Today I lowered the pressure to 95F / 100R and rode 70 miles over mixed pavement types on a road loop I know very well. There is no doubt that the ride quality was more supple with less vibration transmitted and according to my Garmin I didn't go any slower :banana:

Next time I will try 90F / 95R because I still have a mental block with riding in the 80s ;)


Sheesh. You are not about to wrestle a crocodile. Just drop the pressure and go for a ride. You don't need a shrink to get past your adversion. :rolleyes: