Road Cycling - Wheels, Tires, Size, & 'Comfort'

Hi everyone.

I have a Cannondale R400 with Mavic MA 2 SBD 622x23 wheels. Currently, the tires are Specialized Turbo/C 700x23. The bike *really* goes with this combination, but on longer rides I also "feel it" (though tolerable). I also would like a little additional comfort when cruising around with the other half. Here are my questions:

If I read the chart on Sheldon Brown's site correctly, the largest tires I can put on these rims are 700x25....is this correct? And if so, would a change to this size tire afford that much additional comfort as to be worthwhile, or do I need to consider a second pair of wheels/tires? Oh, and how large a diameter before a relative newbie/recreational rider of a couple months who digs a little speed now and then....compromises too much for the "comfort gain"? And one more...

How about rider-weight being a factor in "smallest advisable tire size"? Hmmmmm....okay, that's it. And thanks! ;)

You probably won't notice much (or any) difference by going to a tire that is 2mm wider. I would keep the tires you have now. Later when they need replacing anyway get the 700x25.

What exactly, do you mean by "feel it" after a long ride? Is your butt sore? Your hands? Maybe you'll get used to it after more time on the bike. Or maybe you need to tinker with saddle position or stem length. The tire size likely has nothing to do with it.

Originally posted by cycletourist
You probably won't notice much (or any) difference by going to a tire that is 2mm wider. I would keep the tires you have now. Later when they need replacing anyway get the 700x25.

Kinda thought that would be the case. Thanks for your advice though, tourist....think I'm gonna take it. :)


What exactly, do you mean by "feel it" after a long ride? Is your butt sore? Your hands?

Neither, actually. It's in the arms sometimes. Fatigue. Perhaps it's just the normal "jarring/hard ride" from riding on a style of bike I'm unaccustomed to, and you're right-on when you suggest conditioning and "getting used to it" will remedy the annoyance. I'm working diligently on that. ;)

I thought that larger tires might offer some shock relief and a "softer" ride.

I have MA-2s on my commuter and have used a Conti Top Touring 700x35 on the front and a 700x32 on the rear for years!!! The limiting factor, with that rim, is frame and brake clearance. Even with standard road bike clearances, I bet you could fit 700x28s, but it will only benefit you in terms of comfort if you can reduce tire pressure. What are you using now? Personally, I'd be afraid to use less than 120psi on a x23 for fear of pinch flats. But you'd probably be okay w/90-100psi on a x28. The bike will not feel quite as nimble with the wider tires, but you still can pump them up to 120 when you feel the need for speed.

It could also be the saddle. If it is tilted slightly so that you tend to slide forward, and you use your arms to stay in position, that would certainly do it. Sounds like it should be an obvious thing, but it can be pretty subtle.

Cheers...Gary

Thank you roadbuzz and gmason (I'll do some trial-and-error on the saddle position). And...


Originally posted by roadbuzz
I have MA-2s on my commuter and have used a Conti Top Touring 700x35 on the front and a 700x32 on the rear for years!!! The limiting factor, with that rim, is frame and brake clearance. Even with standard road bike clearances, I bet you could fit 700x28s

Aha....so it can be done! Thanks for the good news, roadbuzz. Took some quick measurements and found the clearances to be 33w x 32-33h in the front, and 33w x 34-35h in the rear. It is an older R400 with RX100 brakes. I'll have to find out how much of a width adjustment they afford, and/or whether I should just consider an upgrade if I ultimately decide to change tires. You guys leave me with many things to ponder and tinker with. I think I'm really beginning to dig this sport/hobby. :)


but it will only benefit you in terms of comfort if you can reduce tire pressure. What are you using now? Personally, I'd be afraid to use less than 120psi on a x23 for fear of pinch flats.

Right now I keep the 23's at 110 without any hassles (so far, at least).

I use Armadillo 700Cx28s @ 100PSI on my touring/commuting road bikes and Conti Ultra2000 700Cx23s @ 105(F), 110(R) PSI on the Bianchi. The heavier, wider tyres are noticeably, but not objectionably, less responsive, and they give me a good excuse when I lag a bit on a group ride.

Besides the clearance issues already discussed, keep in mind that a tire's nominal measurement is not always the same as its actual measurement. It's especially common for tires to be narrower than they're supposed to be. The combination of a particular rim with a particular tire can have an effect on this as well.

So you could move from a given 23 to a given 25 and at the same inflation pressure find no difference in their dimensions -- or a difference of 4mm instead of 2!

If your frame's tolerances are tight, sometimes it can pay to ask around for people with the same rims and the tires you're considering to take a caliper and actually measure them. It sounds like your frame isn't one of those wannabee types that have indentations in the back of the seat tube to the tire won't rub, so it may not be a problem for you. But be prepared.

As to your first question -- what's going to make a difference in ride softness is changing to a tire that's enough larger in volume that you can run it at a noticeably lower pressure without trhreatening your rims. Such a tire is going to not just be wider, it will also be deeper. Whether this would make enough of a difference to justify the cost is debateable, especially compared to easier and cheaper solutions like thicker chamois in your shorts, or a saddle with just a little spring in it, like the SI Max Trans Am, and maybe gloves with gel palm padding. This type of solution is less likely to affect your bike's speed and handling, as changing to fatter, softer tires will.

RichC

I always thought that riding a wider tyre at the same pressure would be more comfortable than a narrower one. At the same prerssure, a wider tyre will have lower rolling resistance.
The downside to wider tyres is weight and air resistance. My own choice for general road riding is a 28mm (real size not marketing dept 28mm).

You should be looking at running wider tyres, not lower pressure one. It just so happens that wider tyres take less pressure, so it can't be helped, but keep them as hard as possible.

I appreciate all the input and expertise assisting me to work this through, guys. Great forum. Lots of stuff to consider & digest. Now that I know it's feasible, I'm leaning toward another two months or so on the 23's, then giving 28's a go. As for the expense, I have a birthday in July and the better half will be wondering "just what would make a nice gift" for such a deserving fella as myself, so if you have any recommendations....price is no option! :D

I just put a Ti seatpost in my c-dale frame and notice a LOT more comfort. Not cheap though.

I also run a saddle with Ti rails. Be sure your saddle is comfortable for *your* butt.

You might also consider going with gloves with more or even gel padding. I used to be a minimalist glove-wise as i was on steel bikes. This is my first Al frame and i recently experienced my first hand-numbness. Switched to more-padded gloves and my hands are happier.

Good luck.

Originally posted by hyperdrive
if you have any recommendations....price is no option! :D
Depends on what you're looking for. Michelin has come out with a bunch of new tires, and my experience is with previous models. Anyhow, if you can stand a tire with green, the Axial Pro is my favorite, but it's a racing tire (read light, rear tire will only get ~2K miles, soft sticky compound which can be a glass magnet). The Michelin Super Comp is almost as good, costs about 1/2 as much, got better mileage, and wasn't as prone to glass damage. (I think Performance may still sell these.) Also had less green rubber than the Axial Pro. ;) The Conti Grand Prix 3000 is a tougher tire, but the ride is not as good as either of the afore-mentioned Michelins. The regular old Conti Grand Prix is a pretty decent tire for a reasonable price, but I've had so many sidewall failures on Contis with the brown rubber sidewalls that I've stopped using them. (Except for my commuter's Top Tourings, which just won't die.) FWIW, wider tires, like x28s, are less subject to sidewall damage, so it may not be as much of an issue.

Good Luck!