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Old 06-20-11, 11:07 PM   #1
beezaur
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How to Speed Up a Marin 29er?

My wife has a Marin mountain bike with 29-inch wheels. The tires are Serfas Drifter 29x2.0.

The bike is really slow.

I ride behind her on my mountain bike, 26x1.75 Continental Contact tires. When we coast downhill I have to start way behind her, slower, and then brake to stay behind. She is waaaay slower coasting than me. It's not a drafting thing, I'm much too far behind for that. Something about the bike.

She tried my bike today and had an instant 3+ mph gain.

We worked on her bike's geometry, which was part of the problem, but those tires suck speed. I can feel it when I take hers out for a test ride.

Any ideas for speeding up the bike? I tried searching for 29er tires, didn't find much.

Scott
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Old 06-20-11, 11:24 PM   #2
Jeff Wills
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29er tires are essentially fat 700C tires. If you're not riding cracked, broken pavement, you should try narrower, lighter, higher pressure tires. You have Alex TD-20 rims on that bike- you could probably run 700 x 32C tires on it with no problem. 700 x 32C or 35C Panaracer Pasela tires, pumped up to 90 or 100psi, and I bet she'll fly.

Are you sure she's not dragging the brakes? (That's my wife's trick.)
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Old 06-20-11, 11:28 PM   #3
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slick tires , ' a 700 32 will feel a lot lighter rolling.
On pavement, knobbys always lose pedal energy in squirming tread blocks

still want fat tire look? , consider Schwalbe big apple tires.
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Old 06-20-11, 11:34 PM   #4
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Are you sure she's not dragging the brakes? (That's my wife's trick.)
That was my thought too, but I don't think so. The bike feels really slow when I ride it.

Thanks for the info. Had no idea 700c would work. Roads around here are macadam, fairly rough but not too bad for potholes and the like.
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Old 06-21-11, 07:04 AM   #5
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slick tires , ' a 700 32 will feel a lot lighter rolling.
On pavement, knobbys always lose pedal energy in squirming tread blocks

still want fat tire look? , consider Schwalbe big apple tires.
That was my first thought too. Knobby tires on pavement suck.

I was surprised with I looked up the tread profile of the Serfas Drifters. That's more of an inverted tread tire so I wouldn't think it would be so bad. If it was my bike, I still think that I'd try the Big Apples just based on the number of good reviews that I've read.

Inverted tread tires have real thick treads. That's good for puncture resistance but not-so-good for rolling resistance. The Big apples are thinner for better rolling resistance but still have a light kevlar layer under the tread for a measure of puncture resistance.

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Old 06-21-11, 12:22 PM   #6
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That was my first thought too. Knobby tires on pavement suck.

I was surprised with I looked up the tread profile of the Serfas Drifters. That's more of an inverted tread tire so I wouldn't think it would be so bad. . . .
I had a tire failure on my 26" mountain bike that I use for commuting over the winter, so switched to the old knobby on the rear while I waited for new slicks to arrive. I was surprised at how well it did at maximum pressure (60 psi).

The Drifters are energy sucks. We got them with the bike (the 29er) because that was all the store had on hand, figuring they would be better than the gargantuan knobbies originally installed. I never tried the knobbies on that bike, but the Drifters . . . it's like having a phantom headwind or something. I had the impression my 26" knobby rear and slick front [and tire liners] was easier to pedal than the 29er bike with two Drifter tires.

Last edited by beezaur; 06-21-11 at 12:25 PM.
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Old 06-21-11, 07:28 PM   #7
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Could be the tires - could be something else.

Have you checked the way the wheel rolls when you spin it compared to yours? Could be bearing cone tightness and condition as easily as the tires.

If you have the money to budget, I`m rolling with the Schwalbe Marathon Supremes in a 700 x 2in size. Even faster, lighter and more puncture resistant than the Big Apples.
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Old 06-22-11, 10:17 AM   #8
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We went to the store last night and picked up a pair of Continental Contacts in 37-622 size, which I guess is basically a 700Cx37.

As an aside, I found this Sheldon Brown page about ISO sizing, which makes a whole lot more sense to me than the 28x business on the tire labels. Now I also understand more about rim measurement. The rims are 622x18, which according to the page linked to, will take anything from 28mm width to something over 37mm.

After a midnight ride - harder to keep up with her for sure - she's pretty happy with the change.

Thanks you guys for all the help. I would have wasted my effort insisting on something that said "29" and not gotten the same results at all.
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Old 06-22-11, 04:34 PM   #9
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Paint it red. Everyone knows that red bikes ride faster.

SB
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Old 06-22-11, 10:59 PM   #10
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Paint it red. Everyone knows that red bikes ride faster.

SB
Red with flames. And those sparkly plastic streamers that go in the ends of the handlebars.
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