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Turbo Cotton or GP4000SII up front?
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If I have one Specialized Turbo Cotton and one GP4000S II, which am I better off using as front versus rear?
I chewed up/sidewall blew out one of the GP4000s way before the end of their life, so it feels silly (and expensive) to buy two new tires right now.

IG: idking90
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Re: Turbo Cotton or GP4000SII up front? [iank] [ In reply to ]
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The GP may be more aerodynamic, in which case it makes more sense up front. Also good to have the lowest RR tire (Turbo Cotton) on the rear because it bears more weight than the front.

But the GP also may have longer tread life, in which case it could make sense in the rear.

Your call on optimizing speed vs wear life.
Last edited by: trail: Jul 4, 15 6:58
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Re: Turbo Cotton or GP4000SII up front? [trail] [ In reply to ]
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I have a 4000sII up front and a turbo cotton in the back. The durability and grip difference is striking. Both in favor of the 4000sII. I have less than 100 miles on the turbo and it is near need of replacing. Several cuts in the tread and I locked it up twice due to the grip difference. The lock up almost killed the tire, it was an emergency stop but is pretty bad.

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Re: Turbo Cotton or GP4000SII up front? [Poseidon2600] [ In reply to ]
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I've got about 150 miles on a set of Turbo Cottons and while I love them for the smooth ride, clearly they are not a tough-duty tire. From now on they will be my race & TT tires only, for use on good pavement. The 4000's to me aren't quite as nice a ride, but their durability on our area's crappy rural roads is exceptional. I would think that if you have to run one of each, that you would get more miles out of the Turbo up-front.
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Re: Turbo Cotton or GP4000SII up front? [iank] [ In reply to ]
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If you are racing, Turbo on the back and neither on the front.
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Re: Turbo Cotton or GP4000SII up front? [rruff] [ In reply to ]
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Ok, so then what do I put on the front that doesn't cost me anything? Right now I only intend to buy one tire, as I still have a good GP4000, and I weigh not dropping $60+ as more important than the relatively limited gains I get from upgrading from the GP4000.
This is strictly for my race wheels, so they might get 20-30 uses a year, including pre-riding the day before and if I'm lazy and have back to back race weekends. The training wheels have a Gator Skin and and an Armadillo tire. I wouldn't dare race with those save maybe a training crit where I don't care about the outcome. As it is, keeping up on Wednesday Night Worlds on those sucks.
My longer term solution is to replace with faster tires on the race wheels than the GP4000s, though. A couple years ago I bought into them as the holy grail of triathlon race tires without much thought. Ready to move beyond them now, but just can't justify tossing the good one.

One question I did just think of re: the Turbo Cotton, is how its cornering characteristics are. I race ITU as well, with the same wheels, so if the Turbo Cottons are fast as hell in a straight line but slide out from under me on wet cobbles, I'd need to think a bit more.

IG: idking90
Last edited by: iank: Jul 4, 15 13:22
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Re: Turbo Cotton or GP4000SII up front? [iank] [ In reply to ]
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Put the GP4000 on the training wheels.

Turbo Cotton should corner fine.

What wheels do you have?
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Re: Turbo Cotton or GP4000SII up front? [Poseidon2600] [ In reply to ]
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Poseidon2600 wrote:
I have a 4000sII up front and a turbo cotton in the back. The durability and grip difference is striking. Both in favor of the 4000sII. I have less than 100 miles on the turbo and it is near need of replacing. Several cuts in the tread and I locked it up twice due to the grip difference. The lock up almost killed the tire, it was an emergency stop but is pretty bad.

That is not a problem with the turbo cotton, it is a problem with you touching the rear brakes at all during an emergency stop. If you are trying to stop as fast as possible, only use the front brake (for a tri-bike on the road, obviously a cyclocross bike in mud, mountain bikes on slippery surfaces, and low riding recumbant this may not apply). The reason for this is due to the high cg and cg being ahead of the rear wheel results in the max braking resulting in the rear wheel lifting off the ground. When there is no weight on the rear wheel it can not apply any braking force. If you are getting any braking force on the rear wheel, that just means you are not braking as hard as you can.
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Re: Turbo Cotton or GP4000SII up front? [rruff] [ In reply to ]
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The point you're overlooking is that I'm not replacing both tires right now. Eventually I plan to, but I'm leaving the GP4000 on one of the wheels because it's not worth the money to replace it prematurely right now.
For race wheels I've got 808 pre-firecrests with a disc cover in nondraft races.

IG: idking90
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Re: Turbo Cotton or GP4000SII up front? [rruff] [ In reply to ]
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Is the gp4000s really that bad a tyre?
So it's worth going for a set of supersonics instead?
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Re: Turbo Cotton or GP4000SII up front? [Tomato] [ In reply to ]
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It isn't bad, I just don't believe it's optimal for racing. For a durable long lasting tire they have low Crr and good aero properties. Depends on your priorities, I guess.
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Re: Turbo Cotton or GP4000SII up front? [iank] [ In reply to ]
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If you aren't interested in using the fastest tires you can get for racing, it seems like a moot point.

I'd probably put the GP4000 on the back because it's more puncture resistant and will wear out sooner back there.
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Re: Turbo Cotton or GP4000SII up front? [rruff] [ In reply to ]
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I am trying to use the fastest tires I can, but here's why I'm not sure that's reasonable:
Based on Tom A's table, the two-tire difference between GP4000s and Turbo Cottons is 4 W@40km/h and 6 W@50km/h.
If I have one of each of those tires, it seems reasonable to assume it would be a 2-3 W differential off of a pure set of two Turbo Cottons.
Turbo Cottons are $80 each. That means I could be spending $27-40 per watt gained while essentially "throwing out" probably 100-200 miles worth of riding to be done on the GP4000.
If money were no object, of course I would buy a pair of Turbo Cottons. I would have done it a while ago, as soon as I realized I was giving something up by riding the Gp4000s, just as I would have upgraded from my CAAD10 to a Venge, S5, etc.
Now, if my math is off or I can somehow get a pair of Turbo Cottons for under $100, then of course I'll go ahead with it.

IG: idking90
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Re: Turbo Cotton or GP4000SII up front? [iank] [ In reply to ]
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"Throwing out" 100-200 miles to be done on the GP4000? Zeros missing? Put it on the front of your daily set and it will last a long time.

I doubt the Turbo Cotton is the best thing on the front anyway. You can buy the good Conti tires for ~$40 from Ribble (cheap latex tubes also). I haven't tested a TC, but I've tested 3 Vittoria Corsa and they are nearly as good as the 23mm SS and ~15% better than the GP4000 for Crr. And those are cheap from Ribble also. Which is why I don't use TC.
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