tntom

My giant FCR has Kenda Kontender 700x26c tires. I have not seen a 26c anywhere else. It was not even a setting on my cateye comp. Anyway here is my question. How much less would a 700x23,s weigh? I was thinking that a set of Michelim pr2,s might make it a little faster.

stapfam

I changed from the Kenda Kontender 26's to PR2's in 23 and they did roll a lot better. Don't know about weight- but the PR2's in 23 weigh approx 220 grammes. I also changed the tubes but Giant do fit a lightweight tube in any case so probably did not change the total weight by a great amount. Took the PR2's to 140 psi and the difference in rolling speed was definitely noticable.

tntom

140 psi. I thought 116psi was max on the PR2's. Can I go to 140? They helped my Felt at 110psi whitch is what I am running now. 140 would have to make a big difference.

stapfam

Run all the road tyres at 140psi- so might be worth trying the Kendas at that. The pressure written on the side of the tyres is very conservative,. the limiting factors are how good are the rims and how much road buzz the body can take after the frame has calmed it down.

I ride a Tandem and just imagine a 25 tyre that is rated at 100psi- with 400lbs bearing down on it. Pinch flats all the time. To cure the pinch flats you up the pressure-----to 140 psi. And boy does that tandem roll.

BluesDawg

Your legs and lungs will make the bike go faster, not a change to very slightly narrower and lighter tires. But after you have worn out the tires you have now, there's nothing wrong with trying something that makes you feel faster. No way to say how much difference in weight. Some 28's are lighter than some 20's.

The Smokester

To answer your question indirectly, for the Continental GP4000 line, the 700x23c weighs 205g and the 700x25c weighs 215g. Given that the tube would be basically the same and weighs lets say about 110g the difference is 100 x 10 / (215 + 110) = 3%.

On the other hand, if you went tubeless...

Grampy™

Operative word here is "little". It will make you a "little" lighter. But it will make it "a lot" easier to find tubes.....

stonecrd

Just another side note going to narrower tires like 23s also makes it a lot easier getting the wheels off the bike. If you have a carrier that requires you to remove the front wheel getting this on/off with 25s or 26s is generally a pretty tight fit compared to 23s.

Retro Grouch 

I'm going to disagree with my friend about tire pressure.

The techie data that I've seen indicates there isn't much benefit in road bike tire pressures greater than 110 or 120 psi. They say the faster rolling feeling is the result of the bike bouncing around more, which actually consumes energy and makes it slower. I understand (maybe from Paul Sherwin) that the professional tour racers use around 115 psi.

On our tandem my wife and I (who are NOT a lightweight team) run 28mm Gatorskins at 100 psi front and 110 psi rear and haven't had a pinch flat in many years. I run similar pressures on my Klein with 23mm tires and 90 psi on my Bridgestone using 28mm tires.

head_wind

This is what I've read too. Most of the paving where I live is now chip-and-seal
so I've lowered my pressure even more, to 100/105 or so.

stapfam

Many of us have funny ideas on how to set up bikes and tyre pressures and what sort of widths to run but my bike is set up for me and the way I want it to feel. I realise that I may not have much "Road" experience- but I have set the bike up for my style and the equipment I use. On the bike bouncing around- I have this too- with one set of wheels only- The wheels will be sorted or going so not a problem. On the back roads round here- I get pinch flats at 100 psi. On the smooth main roads- I probably wouldn't but I don't ride them often.

140 psi may seem high to most- but it works for me. Have tried lowering pressures and it does not work. Prize example is after getting a flat and my pump struggles to get to 90 psi, or is it me. After a flat- the bike is slower- does not respond in the way I am used to and just does not feel right. Get the tyres back up to pressure and no problem. And on the Tandem I use a mini Track pump with no gauge- after a flat- we just pump till no more air will go into the tyre. We checked this after a ride once and found that we were running at well over 140 psi. we must have felt strong that day.

Edit- The point I am trying to make is that I do not Use Data given out or advice freely given. I try it out but if it doesn't work- I just use it as a starting point. I have always been a try it and see person. My saddle position is different to others- not many of us here have the bars set low as I do (Even though i have a back problem) and Not many will have tyre pressures as high as me. Those that do- will be the ones that tried it out and they like it too.

BluesDawg

"To each his own" said the old lady as she kissed the cow.

Me, I've never run over 115 psi in a tire without quickly reducing it. The ride is just too harsh.

zowie

I just went from a PR2 x 25c to a Kontender 26c. Looking at the brake clearance, of which there is little, making changes pretty noticeable, I don't notice any difference. There's definitely more clearance than when I had Rivendell 28s, which are supposed to actually measure 27, and were the absolute biggest I could fit. I suspect the Kenda measures a little smaller than stated but I don't have calipers to check.

The Kenda is rated for 125 psi. 125 psi is fairly high for a 26c. PR2s are only rated for 102 psi in 25c size. (You won't see that on the websites that sell them. They only give the higher rating of the 23c.)

The Kendas were easier for me to mount than the PR2s.

I have only ridden a few miles so far but I did not notice a drop in speed. But I don't take anything away from that. Tires feeling faster or slower is not the same as tires rolling faster or slower. Sometimes it's even the opposite. That is because harder tires subjectively feel faster than softer ones whether they actually roll faster or not. So I'll have to ride my longer regular routes a couple times before deciding based on what the cyclometer shows. Based on the PR2s fine reptation, I suspect I'll be giving up a little speed, but only time will tell.

The Kenda weighs about 80 grams more than the PR2 25. Not insignificant. But not that much either if there are benefits for the trade off. One obvious benefit is the Konterders cost less than 1/2 as much. Another benefit is that I can run them at higher pressure if I wish. If they're really a mm larger (questionable for now), another benefit is I can get a little bit more volume and hence more shock absorbtion. Maybe they'll have better durability? I'm not riding a super light bike, I'm not a light rider, and I don't even pretend to race. So it seems like the modest 80 gram penalty is worth it for me if the tires hold up well.