Switching to 25s

Challenging day for a ride. Temp 73F (nice!), but wind from the south at 16 mph, gusting to 36. It was even blowier than last week, when I cut the ride short because the gusty winds made the bike seem unstable.

But I rode today anyway, because I have new toys. Actually, they’re a lot more important than toys. I bought new tires. The ones on the bike were showing signs of wear. The Specialized Mondo Pro on the front was the original tire, so it’s been on almost a full year. I felt it was losing grip, and the surface was cut up. The Vittoria Rubino Pro on the rear was a nice tire, but had flattened in the center of the tread, and was due for a replacement.

So I put on a pair of new tires. They had to have puncture resistance, and I decided that they had to be 700C x 25mm, rather than 23s. Nashbar had a nice price on just the tire I was looking for, so the bike now has a pair of Hutchinson Top Speed Kevlar Protech tires.

Why 25s? I mentioned a couple of months ago that one of our club members had switched to them, and liked them. That planted the idea. After reading more about the difference between 25s and 23s, I concluded that they were worth trying.

I figured my best bet on a windy day like today was the Veloway. It’s a three-mile circuit, so it would be into the wind half the time, but thickets of cedar and live oak that line the track block the wind somewhat, part of the time.

The ride over there was a taste of things to come. A gentle downhill a mile into the trip often gives me my highest speed of the ride, but today going into the wind, I topped out at 16 mph.

One benefit of the 25s was immediately apparent. They were more stable in the wind. I was also putting the good advice I got last week about riding in the wind to good use, and that helped — but the tires were the biggest change I’d made, and I was pleased to see the difference.

Once I got on the Veloway, another difference was evident. Better grip. I could attack the turns on the course with more confidence than I’d had with the old tires. I did five laps and then headed home, for a total ride of 21 miles. The 25 mm tires do seem to offer a softer ride than the 23s.

One of the arguments people use against 25s is that they have greater rolling resistance than 23s. According to Al Ardizone in the Feb. 5, 2009 edition of Road Bike Rider, that’s not true. He says 25s actually have less rolling resistance, and suggests riders use their weight to determine which size tire to ride. I’m still over 200 lbs., so according to his formula, 25s are right for me.

He’s also a proponent of lower tire pressures, for greater comfort with no loss of speed. Al suggests 85-100 pounds pressure. I had been running 105 lbs. in my old tires, and have the new ones at 100 now — recommended pressure is 87-101 lbs. I’ll decrease the pressure a bit on upcoming rides to figure out what’s right for me.

Interestingly, these might be last year’s model, because Hutchinson’s web site doesn’t list a Top Speed model. Their current Equinox seems to have the same specs as my tire. A check of Road Bike Review shows mixed reaction to the Top Speeds — some say they performed well, other say they’d never buy another pair. Anecdotal evidence is interesting, but a sample of only five reviews is not enough to generalize from.

So I’m looking forward to riding with the new tires. I’ll be watching closely to see if they’re as puncture-resistant as billed, and if they deliver increased comfort with no loss of speed. But after only one ride, I think I can safely say that I won’t be going back to 23s.


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