From 35 to 25. How much difference?
 

Hi,

It is a noob question.
My current bike has Kenda Small Block 8 700x35 tire (350 grams).
I'm considering changing the tire to Conti Gatorskin 700x25 (250 grams, folding).
Does this make a big difference in performance?
I'm averaging about 17mph at a flat surface with Kenda tires.
I wish to improve the speed at about 20mph.

Thanks!
and Happy New Year!

I think you'll get 1-2mph increase. some may say this isn't a big increase, but I think it is. Saving 200grams of rotational weight will dramatically make your bike "feel" faster. Accelerations will be faster and it'll take you less energy to move your bike forward. You are losing like half a pound of weight plus reducing your roller resistance.

Thank you! So that sounds like a good investment to me.

The fact you are going from a knobby tire to a smooth one will make the largest difference.

I literally just made the same switch. I went from 700x32mm WTB cross tires to 700x25mm Conti Gatorskins and before I mounted them I expected there to be some difference but I was mostly skeptical. My first ride felt like a completely different bike. It felt faster and it almost felt like it handled better (quicker maybe?). I'd say it is definitely a worth while investment.

You will notice a huge difference in speed. You will also notice a huge difference in ride quality (it will get rougher).

In my experience, I actually got faster going from 25s to 35s, due to the increase in the corners.

+1

The weight difference probably makes a minimal difference, but those are very different tires.


This is somewhat true, but I wouldn't give it unqualified agreement. The small block tires do absorb more irregularities in road surfaces, but on decent pavement I much prefer the way a slick tire feels. YMMV

At those speeds, the change in aerodynamic drag (less frontal area on narrower tires) will probably be just as significant as the change in rolling resistance. By the way, while you're making the change, get the extra-light ~70-gram tubes to go with those tires too.

Also recalibrate your computer so it gives you accurate speed readings with the smaller tires.

The answer is 10. Do I get a smiley face sticker or anything?

Actually like others mentioned changing from knobbies to slicks is a huge difference in terms of speed. Also, I did notice a difference in weight when I changed tires from a heavier one to a lighter one (Michelin Trans World City's to Specialized FatBoys). Although I do understand they are different tires.

Thanks for all nice and helpful comments! I got the purchase approval from my wife. :)

Used to have a hybrid that came with 700X40 medium knobby tires.
Switched to 700X28 slick tires, didn't see a huge improvement on my
commute time(1 hour and 1/2 each way). Maybe 5 minutes faster.

Oh Crap! I bought the tire, but my tire tool is broken while removing the old one.