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What will I be loosing in upgrading to 25 or 28 tires?(11 posts)

What will I be loosing in upgrading to 25 or 28 tires?niteschaos
Oct 18, 2002 7:19 AM
I ride 700x23 road tires at 120 to 110 to aviod pinch flatting on the awful roads of Atlanta. I bust rear spokes now with regularity. Would increasing tire size to 25 or 28 instead of 23 make a difference in breaking spokes? Would it allow a more comfortable ride? Would it increase rolling resistance.

These tires are going on my CXP21 Mavic training wheels, so weight isn't an issue. I just want to make my wheel bulletproof on the Atlanta asphault.
28 tires on 1 bike? that's a lot of rotational weight!_rt_
Oct 18, 2002 7:26 AM
hehe. sorry, couldn't resist.

increasing tire size to 25 or 28 will increase your rolling resistance somewhat (whether you'll notice is another issue entirely) and make for a somewhat more comfortable ride.

for training tires, though, they'll be fine.

rt
give it a tryDougSloan
Oct 18, 2002 7:40 AM
I used 28's on my Colnago (barely fit) for the last 100 miles of the 508 this year, expecting some nasty roads like last year (they repaved some, though, making it much better).

It's hard to quantify, but I did not notice a loss of efficiency, even on the smoother parts. I pumped them to 110 psi, which should make them decently efficient.

If the roads are rough, there is a chance you are actually faster with the wider (and taller) tires, as you bounce around a lot less. Bumps get absorbed, rather than deflecting you so much. If you do long rides, the extra comfort may result in a little less fatigue, too.

Sure, you'll have a little more frontal area, too, but if you are talking about using them in training, or when high speed is not critical, who cares.

As for a difference in breaking spokes, I have no idea. If spokes break from jolts to the rim, these tires would help. You may just have badly constructed wheels, though.

The feel of the tires was vastly different. They really smoothed out the little bumps, almost feeling like a small travel suspension (I guess it is, actually).

Try some Conti Ultra 2000's in 28 mm. They are not expensive, so it's worth the risk, I think. Excel had them for $30: http://www.excelsports.com/new.asp?page=8&description=Ultra+2000+Tire&vendorCode=CONTI&major=1&minor=27

You might need bigger tubes, but the standard ones might work, too. It may depend on the tube.

Doug
one more thingDougSloan
Oct 18, 2002 7:43 AM
Don't forget to recalibrate your speedo, too, as the circumference will be substantially larger. You might mistakely attribute lower indicated speeds to the larger tires, when you may not really be going slower.

Doug
I run 25 and 28, even 32...rwbadley
Oct 18, 2002 7:44 AM
I have 25 on the trainer and 32 on the town bike. A great way to go. As long as you have clearance, go for it.

The 32s on the cross bike I run at 90psi, it rides great, and is no slower than I am! They don't need to be expensive either. I have had some of my best luck with the 'cheapies'.

RW
Two things:Spoke Wrench
Oct 18, 2002 7:49 AM
1. 28's might be a little marginal fitting between your brake calipers. You might have to install the wheels with the tires soft and inflate the tires afterward.

2. If your CXP-21's are breaking spokes on the left side, you might just need a little more spoke tension. Try this: LOOSEN all of the left side spokes exactly 1 turn. Then tighten the right spokes 1/2 turn. Finally, tighten the left side spokes 1 1/2 turns. That should give you the tension you need on the left without rounding out the right side nipples.
re:Fixed many broken spokes on CXP21's on an AIDS ride.dzrider
Oct 18, 2002 7:53 AM
All were on Canondales and seemed to be built with the non-drive spokes pretty loose. I'd check out the quality of the build to remedy the broken spoke problem and use the bigger tires for comfort, flat resistance and durability.
re: Spokes and TiresChen2
Oct 18, 2002 8:42 AM
I don't think your tire size is causing your spokes to break. How are your CXP 21's laced? I've heard of several problems with radial laced CXP 21's of C'dale bikes. I like the answer Spokewrench gave you, provided that you can get the rims true. I'd think twice about going above 25mm on the tires, unless you're really a big person. I think tire sizes on road bikes should be relative to the total weight of the loaded bike and rider.
~Al
More info on the situationniteschaos
Oct 18, 2002 6:33 PM
My wheels are 3cross laced. I wiegh 190 pounds and ride 140 miles a week on some of the roughest roads still ridable by road machine. From reading other reviews, for training I can't go wrong with larger wheels. I'm not worried about rolling resistance, just cornering grip and increased smoothness.
More info on the situationTrent in WA
Oct 19, 2002 12:38 AM
My thoughts:

If you're breaking spokes, it's not b/c your tires are too skinny, but b/c your wheel wasn't properly tensioned. If I'm not mistaken, the CXP21's are pretty standard for machine-built OEM wheels. That's not a problem if the spokes were brought up to full tension by your shop, but if they weren't, you should take care of that before going on tire quest. Have a competent wheel guy at a shop tighten them up for you, or get a copy of Brandt's _The Bicycle Wheel_ and do it yourself--once you do it for one wheel, you'll do it for them all, and you'll be a much happier rider.

Having said that, once your wheels are as solid as they can be, fatter tires will make your ride much, much more comfortable, and I really doubt that you'll notice a speed difference. Give 'em a try. Avocet Duros are nice, as are Panaracer Paselas.

Hope this helps,
Trent
re: What will I be loosing in upgrading to 25 or 28 tires?jrm
Oct 18, 2002 6:38 PM
I went from a 23cc conti grand prix to 28cc panaracer Tserv's for messengers. For the streets of Oakland and SF they rock. It takes alot to flat. Their rated or 105 psi but pumping them to 120 isnt an issue. Tere claimed weight is 275gm each.