Here is a primer: https://www.slowtwitch.com/...der_How-To_3007.html

Schwalbe has up to 80mm with a removable core, which I don't believe is quite enough for your 808.

I know this isn't what you want to hear but I don't think you need to carry two inner tubes with you and to be honest I don't know many people that do. Hell a lot of people don't carry anything who are serious about placing high up. Blown tire blows the day.

This is my advice take it for what its worth. Carry one spare tube with a stem long enough for your 404. Remove the core and put an extender on that is long enough for you 808. Put the core in it. Now take one of those little black plastic "wrenches" and roll/fold up your inner tube with that little black piece sandwiched in the middle. Tape it up. Thats all you carry. Blow the back and change it. Blow the front and use the black "wrench" piece to unscrew the core and extender. Then put the core back on the stem without the extender. Now change the front. Blow a second tire and you are stuffed, it's just not your day so wait around for someone to help you out.

Now if you are new to this fiddling with the cores and extenders on the side of the road may seem difficult, but I can assure you with some practice it is not a big deal at all. My experience (contradicting the ST article) is that these cores and extenders with the rubber seal do not need teflon tape. Others may disagree but that's my experience with Silca extenders and anybody's cores. And they certainly don't need any torque just to get you to the end of the bike leg.

Thanks TravelingTri. I carry two tubes because one time on a training ride I had one flat, changed it, then got another in the same wheel 5 min later! There was a microscopic piece of glass remaining in the tire that blew the second tube out. And, of course, I was 20 miles from my car when it happened out in the middle of nowhere. But you're right... in theory the race is blown anyway if I had to change 2 flats (as I am slow anyway and barely make the cutoff) so will probably take your advice and just carry one.

I always carry two tubes, each set up for wheels I am using. If you happen to flat the same tire twice you will still have the ability to switch things around to at least get you by.

Get the Silca RVC valve extensions https://silca.cc/...alve-core-extensions

Size chart here

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Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

Take a look at Continental Gatorskins or the Gatorskin Hardshell for when you are out training. Good Luck.

I do the same as TravelingTri except that I have to remove the extender if it's for the back tire because I run a disc.

Removable cores in my experience are way less hassle because I always get a good seal. It just means that the little valve can actually be unscrewed and removed as opposed to putting the extender *over* it.

By the way, when you change a flat, it's a good idea to inspect all the way around the tire for what might have caused it. You can run your fingers slowly along the inside of the tire, just be careful not to do it too fast so as to get cut by whatever caused the flat!

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Coach at TriForce Triathlon Team: https://www.triforceteam.com

Thanks all... I appreciate the advice.