Latex tubes.....school me

Well, that's the deal for me.  If there is a flat in a sprint the race is over.......it's not a matter of finishing..... not happening, it'll be a walk off.  For me seconds is no matter, but not for my kids in their races....so are there seconds to be gained?  And if so, is a flat so much more common that it would negate any possible small gain?  Is there any concrete data on speed gain?

The savings from latex tubes varies by tire but data suggests for some tires it is roughly 3 watts per wheel.  This has a few comparison numbers:

http://www.biketechreview.com/tires_old/images/AFM_tire_testing_rev9.pdf

The GP 4000s is supposedly about 3 Watts per wheel as well.  You can use something like bikecalculator.com to see what 6W might save you in a sprint or Olympic but probably 15-30s.

The flatting question is probably harder to answer.  The consensus seems to be that Latex tubes are more prone to installation error flats.  Things like bits of tube stuck between tire and rim, or bad rim strips.  If you get the installation correct most people claim to actually get less flats.  They don't seem to suffer from pinch flats as easy as a butyl.  If a nail or glass makes it through your tire you are probably getting a flat either way.  Slowtwitch ran a recent test comparing tire sealants and their results showed that latex tubes seem to work better with tire sealants.  So best bet against flats may be a latex tube with some sealant.

The other con to latex tubes is that they simply lose air faster, so you'll have to inflate your tires before every ride.  Personally I think you should be doing that anyway.  Oh, CO2 makes this even worse, combined with the installation issues means you should carry a butyl for a spare.

How do you do that? (bolded part)

Normally you need a latex tube with a removable vale core, which I think most have.  You unscrew the valve core and squirt about 2oz of selant then put the core back in and inflate.  Here is slowtwitch's sealant test which may help you decide which sealant you may want to try.

LB, here is the deal on latex tubes. Better ride, 3 watts savings per wheel. They are NOT more likely to flat if installed properly.  However, you must be a bit more careful that the latex does not get caught under the bead during inflation. Additionally, they lose air more quickly; as in, you will have to pump the tires every day. Not a huge deal, but perhaps something to remember if you have to rack your bike the day before. Biggest thing is if you let it deflate too much, maybe don't inflate for a week, you must be very careful again when you re-inflate to make sure the latex has not slipped under the bead. The latex likes to be sneaky.

For "that guy" i would say its a no brainer to do it. You're probably saving him 2% of effort or gaining 2% of speed, who cares what the race distance is, that is certainly significant. As long as you are careful and pre-ride on the tubes before your race (that morning and the week of) there should be no problems.

As far as sealant, that will probably make the tubes worse than the butyl you were using. Sealant ruins rolling resistance and doesn't get you anything. A big puncture or blowout will not be helped by sealant.

On second thought, please give your son extra thick butyl tubes, lots of sealant, and gatorskins. I could use the extra 40 seconds.

ETA: I doubt he is carrying a spare in races, but for training rides definitely use a butyl.

x3...sums it up pretty well.

Leave the latex tubes in the race wheels and only use them for races.  Constantly changing from latex and butyl increases the chances for installation errors. 

Also, keep in mind that tubes and tires work together.  A latex tube in a crappy tire won't make a difference because the tire won't be supple enough to take advantage of latex's supple properties as well.  Sort of like buying a really soft down pillow and using a cardboard box as a pillow case.

Yeah install can be a bit more involved to ensure the tube gets seated properly and not pinched, learned that the 1st time I installed one!

Read Tom Anhalt's blog (http://bikeblather.blogspot.com/), he has data on some of the latest tires being produced with expected road wattage saving at 30, 40 and 50 kph.  GP4000s w/latex had ~5W saved at 30kph and ~8 at 40kph. With 5W worth ~1 sec per mile it can be worth it regardless of ability given any time saved at the finishline is the goal for most racers.

I've been using latex in my tubes for a couple years now, I got lazy and have left them in as I race and train the same wheels (Felt TTR2).  Have not had a flat in them since I've been using them, barely!  I say barely as if you or your son will be using them make sure you replace the rim tape with some real good rim tape.  My wheels had some good cloth tape and during my last sprint race all was well until I came back to transition after the race and found I had a flat, and thought "phew that was close".  I checked out the puncture and it was not due to anything in the tire but the tube found its way through a weakness in the cloth tape over a spoke hole, it eventually went through and popped.  The hole in the tape was tiny, like 1/32 tiny.

Exposed spoke holes is the only thing that have ever caused me a problem with latex tubes.  I've never flatted with them while riding but have flatted plenty with butyl.  When I had the spoke hole issue, the tube blew while I was inflating it.  It's a sickening sound hearing $15 go *POP*!

And I've only had 1 latex tube flat. That one was due to a staple working its way in. A butyl most definitely would not have survived because the spare I used did not make it either. (oops)

Anything I would have said on care in installation being about the only difference towards this has already been said in earlier posts.

Can I get some more opinions on the "feel and handling" aspect? It surprises me that the tube could really make much difference in the feel and handling, would think the tire does most of that. Is it really enough to feel a difference?

If the latex tube is more supple does that mean you have to run a higher pressure in the tire? Would seem if the tube is more supple, the same pressure would give you more slack in the tire and this increase rolling resistance. So do you have to go 120psi in a latex where you would normally go 110psi in a butyl?

If you assume 300 watts average power, which I believe LB's son is close to, 3 watts per wheel, 6 watts total, is 2% of the total power.  Running tubulars would require him to get new wheels.  And you spend how much time running and cycling and swimming to gain a few seconds in a race? Taking a few minutes to put in tires would seem like an easy investment.

Being more supple does not mean you need more pressure. A tire can be more supple. For instance your conti 4000s has a higher thread count than your gatorskin, making it more supple; you would use the same pressure. Optimal pressure is governed by load and by weather conditions.

The feel and handling is better because of how the tire will conform to the road. a more supple tire (and tube) will conform with less pressure applied, giving you better "grip." Tubular tires tend to have a better road feel because they do not have tubes inside them like a clincher does. A latex tube gets you closer to a tubular "feel."

I tend to just use what brand I can find. Most of them have removable valve cores so you could replace it with a longer stem, and move that stem from tube to tube if you so desired.

Not sure what you are on about, could you provide some evidence to back up whatever you are trying to say? There have been multiple published tests by third party sources that have all confirmed something close to a 3 watt/wheel difference when using a latex tube.

Yeah, he'll go 300 avg. watts pretty easy on a flat sprint course....and unlike my race, seconds absolutely count for him and could easily be the difference of a podium or not.  Last year at Sprint nationals the difference between 4th and 6th place overall was 1.18 seconds, with less than 25 seconds between 4th and 11th.

You want latex tubes and good tires for sure.  Install the tubes a few days ahead of time and get a couple of rides in on them to make sure they are installed ok and you'll be good to go.

and check the rim tape!  twice!