If you think it makes you faster it makes you faster!

http://photos1.blogger.com/blogger/6...adthorns.3.jpg

These thorns (goatheads) are the source of 95% of my flats. They're all over the place around here.

Gak!

Darn goatherds!

Back to racer-tech...

Any problems with using a double chainring as a single in a 1x11 setup on my CX bike? Anything to pay attention to?

I'm using a SRAM Force CX1 RD with a clutch, so shouldn't need a chain guide. But should I use one anyway?

I believe you'll want a narrow-wide chainring with no pins/ramps to facilitate shifting, otherwise you could/will have a derailment in the front. They're not that expensive. Sram x-sync. People may say get chain retention in the front for 'cross as well.

A double chainring will have ramps and pins that may make it more likely to dump the chain than a purpose made single ring. Even with a clutch RD, I wouldn't personally run a 1x setup on a cross bike without either a chain guide or (preferable) a narrow-wide chainring. I like the Raceface narrow-wide chainrings which are a lot cheaper than the SRAM CX1 rings.

I think I have dropped the chain once with a narrow-wide in front and clutch RD, which is a lot less than I used to drop the chain with a regular single ring plus outer bash-type guide and inner k-edge catcher.

I do it, and I've had no problems. BUT I also have an FSA carbon bash guard and a K-Edge chain keeper that wraps over the top of the chain. The combination of the chain keeper and bash guard mean the chain cannot go anywhere.

I also don't use a clutch RD.

When I lived in West Texas, I rode Maxxis Refuse tires because they were cheap and very tough, and could stand up to most of the cactus thorns that were everywhere.

On the MTB, I had to run Slime Tubes.

so back to tires.. continental gp4000 ii vs vittoria corsa cx.. the gp4000 has lower rolling resistance, and has around 160 tpi. the corsa cx is 320 tpi, despite marginally higher rolling resistance. Is it safe to assume then that you get a hell of a lot more grip with the corsa cx? sliding out is a constant worry of mine, particularly for crits. I see videos of guys sliding out at tulsa tough on that final corner, and it scares the bejesus out of me.

so in that respect, are sworks turbo and corsa cx still the top of the line in racing not only because of lower rolling resistance, but also grip? What are some other characteristics that's desirable in a racing tire?

FWIW that particular corner has 2 manhole covers in the middle of it and the ideal line is to thread the needle between them. Guys sliding out are very likely hitting one of them. I've raced it twice, once in the rain, had no trouble on that corner.

I've raced on GP4ks, s-works turbos, and schwalbe ones. I've never washed out on any of them, but I do have a lot more confidence in the GPs and s-works than in the schwalbes, they just feel stickier underneath the bike. But honestly I think washing out is more often a failure of technique than a failure of tires.

LOL no. First of all TPI has nothing to do with grip, second of all the only tire you're liable to find that's as grippy as the GP4000S II is the S-Works Turbo (designed by the same people).

That said, I agree with GC. I currently am on Schwalbe Ones, and they feel very, very sticky indeed. So even if they aren't as good as the 4000S II in that regard, they're more than good enough. I've hit some pretty absurd lean angles on them. I have no real personal experience with Vittoria's tires, but a) there's no way they're grippier than the GP4000S II, and b) they're pretty much bound to be plenty good enough anyway.

And back to 1x :) ... a friend is perma-lending me an old aluminum cervelo P2 frame. I'm thinking of building it up with a 52 single chainring and 11x28. I figure that spins out around 42 mph and still gives me a small enough gear to get up small hills. I could also swap a 54 on there for super flat courses. I figure the bike will heavy enough that it wouldn't be ideal for any course requiring small ring climbing anyway, and the aero benefit of no FD is meaningful.

Yes, there are multiple factors that affect traction. you're referring to rubber formulation, and judging by the similar rolling resistances, I assume that the suppleness between the two rubber are pretty similar. thread pattern also has an influence. the vittoria's threads seem much better for dealing with the unevenness of the roads. the sworks turbo has very similar thread design as the corsa cx. seeing that they were designed by the same people who made the gp4k, there must be something about that thread pattern that's appealing to racers

"Nothing to do with grip" is an overstatement, but the point is that you can't look at the TPI of a tire and determine that it has better grip, anymore than you can look at the TPI of a tire and determine that it has lower rolling resistance. With these same tires being perfect illustrations of that fact about Crr. You could certainly make a case that tire suppleness will have consequences for grip, but provided you get your pressure right I don't think it matters much at road pressures. The Schwalbe One has a much stiffer casing than the GP4000S II, but so what? I run it at ~15 fewer PSI and traction isn't a problem. I've scuffed my Speedplays a couple different times with these tires.

15 fewer psi sacrifices, what like 2-5 watts?

More like 2-2.5. Per tire, though. If that's been my problem this season, I will eat my hat.

what's the difference between perma-lending and gifting?

also, don't they have TT's that are rolling hill? I assume that you'll be using a standard double crank, with only 1 ring, so what about cross chaining?

My guess is perma lend; its yours until I total my bike and need it.

We have a 50x11-28 (wife and I share) that I built for mild uphill TTs like Killington. Cielo ended up being way too hilly for that setup so we used road bikes. So as long as you know it's not the best tool for every job, build away. I went sram x-sync, 6870 RD and ultegra right side TT shifter. Cheap.

As for cornering grip: I've found that my mental limit is met before my tire limit in normal situations (no sand, manhole covers). I recall a situation at the end of an interval where I had about 10 extra MPH around a corner and was in the pain cave. Parts of my tire that have never seen pavement before finally met it, and it was fine.

Perma-lending is when the friend is kind of a hoarder and also can't be bothered to come up with a price. You should see this guy's basement. I doubt he'll ever want it back but if he does, well, it is still his.

I'd probably get a dedicated 1x crank but I have one chainring on a double crank on my winter bike and it's just a matter of spacing out the chainring to more or less center it.

Thanks for the advice [MENTION=221607]Harlan[/MENTION], I think I'll go for it.

how would you space out the chainring? the chainrings can only be spaced out in the opposite direction of where you would want it to be for a 1x. it may be trivial though. you can probably get away with just using the inner ring bolts.

The raceface chainrings have indents on one side. It seems to be centered, anyway. Hasn't been a problem.

The 1x ring I have is made so it's more towards the center of the crank, and they say you can run it on the inside if you have to (aggressive chainline).

in my testing, the corsa cx came out faster than the gp4000s ii in terms of rolling resistance. (tires can and do vary based on the samples you've got.)

that said, by subjective feel i believe the gp4000 has 'more grip' than the corsa cx. neither one is an issue in dry conditions, but i notice it when pavement is wet/slightly wet.

s-works turbo (gripton; not the turbo cotton) has a subjective grippy feel to it. rode them for the first time in the wet the past few days and i'd rank them at least as good/grippy as the gp4000.

i never rode the turbo cotton in wet conditions. it does offer a nice ride -- very similar to the Corsa in terms of quality. i feel like of the tires mentioned the gp4000s are the most harsh. we're not talking gatorskins, though.