jambon

Hi ,

I have an older road bike that takes 27 x 1 1/4 tyres . I have always found the tyres to feel very spongy and to deform a lot when I ride them even with the Pressure at the max recommended 75 PSI . Granted I am toward the heavier side weighing around 100kg . I have occasionally pumped in more pressure than the 75 PSI to maybe 80 or 85 but regretted it as I almost instantly got punctures .

I am looking at replacing them with an offering from Schwalbe with a max PSI of 90 or some continental gatorskins that can go all the way up to 120 PSI .

So... Will putting on a tyre that can take more air pressure get rid of that sensation that I am riding on overly flexible energy wasting mushrooms ? Will the gatorskins at 120 max PSI be the obvious best solution ?

Thanks for any inputs,

J

Retro Grouch 

Gatorskins @ 120 psi will definitely have a firmer feel. I wouldn't expect them to be significantly faster.

CliffordK

Are the sides of your rims straight, or hooked?

There is supposed to be a pressure limit for unhooked rims.

"Instant Flats" sounds a bit odd. Perhaps there is something already embedded in the tire, and presses it against the tube at higher pressures.

Gator Hardshells are supposed to be Continental's most flat resistant tires.

JohnDThompson 

For any given tire and road surface, rolling resistance is roughly inversely proportional to inflation pressure, so a higher pressure in principle will give lower rolling resistance. But there are other factors to consider as well. Higher pressure transmits more road vibration to your hands, which can be uncomfortable and tiring, and on a rough surface, high pressure can make it difficult to control the bike.

Tire construction also influences rolling resistance: knobby tread and thick, stiff sidewalls also increase rolling resistance. So look for a tire with a smooth or relatively smooth tread and a supple sidewall. If you have problems with punctures, a tire with a puncture-resistant layer under the tread is worth considering, like the Panaracer Pasela PT.

In my experience, 32mm wide (1-1/4") tires run at 80-85 psi work quite well.

rumrunn6

go for it! just don't pump the front tire as hard as the rear. it doesn't carry as much weight so doesn't need as much pressure. also, one benefit is w a lower front pressure is it won't feel so twitchy. can't tell you how much less, but someone else can

get new tubes & thick cloth rim tape

dsbrantjr

I would look to causes other than just raising the pressure from 75psi to 80-85psi for your punctures.
And harder tires do not necessarily equate to faster; many studies indicate that there is an optimum pressure, related to weight and tire size.
Bicycle tire pressure calculator
https://janheine.wordpress.com/2016/...ure-take-home/
https://janheine.wordpress.com/2010/...-and-pressure/

MrSmokey

the puncture thing is a little odd to me, make sure something did not make its way inbetween the casing and tube, and as mentioned make sure your rim tape is intact, also if the valve is a little off centered when you go way up in psi, especially on older tube they have a tenancy to blow there where the valve is fused to the tube, or start a slow leak there.

It is all relative, higher PSI tires may not necessary help you with the rolling resistance, and may just cause handling and traction issues and discomfort. go to bicyclerollingressistance dot com and look at many different tires, PSI is not necessarily related to less resistance on the whole, though relative to an individual tire, yes. tons of different casings and compounds... One could go on day discussing this subject. doing some research on that website might help you figure it out.

i cannot link yet, but if you go to bicyclerollingressistance they have the conti gatorskin you mention, for reference it uses 19.3 watts at 120psi, and 26.2 watts at 60psi.

See if you can find a tire similar to what you have on there to reference against the ones you are looking at buying.

Take all the following with a grain of salt as it is mostly all generalization, and there can always be an exception, but as mentioned keep your front tire a little lower pressure than the rear, it will help with comfort and certainly with traction and handling. with each given new tire i have ever used, i have had to play with pressures till i got them into a sweet spot. Just like on my rwd cars, i prefer my bikes set up looser in the rear, and would rather lose rear traction in cornering first. Slipping the rear is far easier to correct than slipping the front at speed.

In general, and it depends on the compound, but the higher in psi you go up in a given tire the more traction you will lose. higher psi will shrink your contact patch, lessening traction. Higher psi stiffening the tire will lessen its ability to squat/squish and adhere, conform, and grip the road when forced, and will increase its tenancy to skip. with that in mind, think about the amount of weight you have on the front and rear at a given moment at speed, etc.

I may be repeating things you are already aware of, but i hope that helps.

MrSmokey

alrighty, i can link now so i will give you direct examples.
for high contrast, compare the conti gatorskin you were mentioning as a possibility to the conti speed king (race sport/black chili compound)

conti gatorskin takes 19.3 watts at 120psi
Continental Gatorskin Rolling Resistance Review

while the conti speed king takes 19.1 watts at ...25 psi, and 14.5 watts at 55 psi, these are higher volume tires.
Continental Speed King II RaceSport Rolling Resistance Review


In your size you could go with the well traveled schwalbe marathon green guard. Folks love that tire, high puncture resistance, and i believe people have exceeded 60,000k on them... it at 75psi is using just around the same wattage as the gatorskin does at 120 psi. It probably also is a better tire for a wide range of use and conditions.
https://www.schwalbetires.com/node/3464
Schwalbe Marathon (GreenGuard) Rolling Resistance Review

Bike Gremlin

In my experience - 4 bars pressure is almost glass proof - the tyre doesn't provide enough firmness for most glass (or sharp metal) objects to dig in and puncture - even in the wet.
The next limit is over 6 bars - going higher than that makes tyres a lot more prone to picking up sharp objects - especially when it's raining. Even "puncture proof" models are note immune - unless going for models with higher puncture resistance that seem to roll like bricks and defeat the purpose of having the air in the tyre.

So my choice is going wider. Tyres of good quality will roll fast even at lower pressures - providing better grip and comfort. For 100 kg rider, 32 mm, or even 28 mm wide tyres can go fine with 6 bar pressure. Most good quality tyres can be pumped to that pressure safely. Gatorskins being a bit harsh, unless your roads are thorn ridden, I'd go with a nicer rolling model, Vittoria, Schwalbe, Continental - whichever you prefer without "puncture protection" as a main selling point.

nfmisso

VERY IMPORTANT are your rims the current standard with hooks to grab onto the tire or the old standard straight sides?

Given that they are currently 27 x 1¼ ; there is a HIGH likely hood that they are straight rims, this is further supported by the issues you had pumping your current tires up to 80-85psi.

If you go too high a pressure with straight sided rims, the tire blows.

MrSmokey

glad you caught that!
here are additional notes from Sheldon Brown.
27 Inch Bicycle Tires from Harris Cyclery (ISO 630 mm)

"Traditional 630 mm (27 inch) rims were straight side design, but in the late '70s they evolved to a "hook edge" design which would permit the use of higher pressures. These days, many 630 mm (27 inch) tires are marked "For hook edge rims only" (some companies use the term "crochet type" instead of "hook edge"...this is the result of poor translation.)
The fact is that modern 630 mm (27 inch) tires will work on older straight-side rims, but they won't handle as much pressure as they are capable of with hook edge rims.
Generally, the "rule of thumb" for traditional 630 mm (27 inch) tires is that they should be inflated to 70-75 psi. This shouldn't be a problem with any tire, despite whatever disclaimer the manufacturer puts on the sidewall. However, if you're restricted to this pressure range, you probably shouldn't be running tires narrower than 1 1/8, or preferably 1 1/4, unless you're a very lightweight rider."

Bill Kapaun

WHERE are the holes when you flat?
If on the rim side, you need a better rim tape.