4000s 700X28 tires
- Thread starter Sonnybea
- Start date
velocio
Austrian roadside steckerlfisch (fish on a stick)
Folks generally find that Conti GP4000s II tires run larger than the marked size. My 28mm GP4000s II's measure 31mm wide on Pacenti SL23 rims, which is about what everyone who measures them seems to get +/- .5mm. 100 psi is very high pressure in a tire of that size even with 205 lbs of rider. When you wrote "I tried 100psi nice ride but I worked harder" does that imply 100 psi is lower than you'd normally use in that tire? At 180 lbs I ride that exact tire at 70-75 psi and that's more pressure than necessary or recommended for best comfort and efficiency.
You may want to consult a tire pressure suggestion program (I hesitate to call such things a "calculator", which implies more science to these things than is probably appropriate). I just checked https://info.silca.cc/silca-professional-pressure-calculator and for a system weight of 230 lbs and 31mm wide tires it thinks just shy of 70 psi is optimal. Here's an Buycycling article that discusses this topic: https://www.bicycling.com/repair/a20004232/how-to-achieve-the-perfect-bike-tire-pressure/
Great tire, but that'sa lot'sa pressure!
-Jack K.
Thank you for the info I got to get out of the past about tire pressure
The 28s had a nice smooth ride even at the high pressure
One question are you more acceptable to pinch flats
velocio
Austrian roadside steckerlfisch (fish on a stick)
I can't recall a pinch flat in the last couple of decades. Actually, I seem to lead a charmed life with respect to flats of all types. Other areas of life are less charmed, but flats are something that happens to other folks. Keep in mind that high pressures are required to avoid pinch flats on skinny tires. When I started riding 20mm (and even 19mm) tires on recreational sporty road bikes were all the rage. My first bike as an adult came with 20mm tires with paper thin tread and sidewalls apparently made from paper thin paper. Even at a scant 125 lbs (yah, I weighed less then) I had to keep 100 psi in those or they'd pinch flat on the first pothole. High quality chubbier rubber at lower psi can be simultaneously faster, more comfortable and more tolerant of banging into potholes.
Sonnybea also asked: "Is there a difference between tubes a d tubular pressure" ...
Tubulars and tubeless setups can be run at lower pressures without concern for pinch flats, but I don't recall any of the bicycle tire pressure suggestion apps differentiating between tire setups using tubes and not. I suspect that in most, or even all, real world cases the suggested pressure that balances performance and comfort is considerably higher than the minimum pressure that can be run safely and provides decent pinch flat protection.
Sounds like you can easily let 30+ psi out of your front tire and 25+ psi out of the rear without much fear of pinch flats. Try it, you may like it. And if not, it's easy enough to pump 'em back up old school rock hard.
-Jack
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super slim
Zen MBB Master
The Enve link is excellent with different pressures for Road, Dirt, MTB AND lower pressures as the rim inner width increases!!!!
velocio
Austrian roadside steckerlfisch (fish on a stick)
But I have no confidence that the gauge on my 30 year old Silca Super Pista is accurate to better than +/-5 psi, so I dunno if a refinement of a few tenths psi in my optimal tire pressure guesstimate would mean much out on the road. Truth be told, a good bit of the time i use my well calibrated thumb to check tire psi before deciding to break out the Silca. As good as my thumb is I suspect it may be even less accurate than the Silca's gauge. Oddly, even with this lack of accurate tire pressure data I still manage to enjoy the warm sun on my rides and the cold beverage after.
Yah, I'm old, slow and grumpy ...
-Jack
velocio
Austrian roadside steckerlfisch (fish on a stick)
Matthew,
If your "Enve AR's" are the "SES 4.5 AR" rim in the table and you're riding pavement, then the pressure suggested in Enve's table is 62 psi. The pressure you're using is right on the money.
-Jack
Michael Fasher
Member
The GP 5000s are significantly smaller then the 4000s. My dad has a Specialised Tarmac and the 4000s barely fit but the 5000s have plenty of clearance.
jond
Zen MBB Master
yes I noticed the same with tubed gp 4000 v 5000. The 28 mm 4000 is close to the 32 mm 5000 same rim.
gee your dad must be upset about owning a tarmac.
jond
Zen MBB Master
Not much crown clearance. Any debris look out. I ran them at 90 psi. Actually i run my 25 s at 90 too. Comfort is speed. I run 32 mm conti gp 5000s tubed at 50 psi on the pelso.
