Thanks in advance for any advice…

I'm thinking of converting to tubeless for racing, but will be using mavic 317 rims. Currently shod with Small Block 8s, which seem a little loose- will it be much hassle to get these working?

My main concern is how quick is it to sling a tube in while racing- presume a base tape stuck down with latex, and the other concern is how easy is it to change tyres bewteen laps in a 24 hour race, in the rain, in the dark? I suppose if it comes to it I will just put tubes back in?

Loose tyre's a problem, it needs to be a tight fit to work properly. You may get away with 'bulking' the rim out with tape, but you may not.

If you go for a Stan's conversion kit (or ghetto) you'll have a rimstrip in there, which you'll have to remove before installing a tube, it's not particularly easy. Saying that, in a number of years of using rimstrips for tubeless I never put a tube in, I don't even carry one now.

I've got 317 rims and I'm running them ghetto tubeless with non-UST tyres (Maxxis Advantage & Ardent). No problems so far. You'll find with Kenda tyres that it's not so much the looseness of the tyres that's the problem, it's the porous sidewalls which will piss sealant out for ages before they seal. Maxxis tyres seal immediately using CO2.

Thats good to know, if I was racing on my own it wouldnt be such an issue- but with mountain mayhem coming up I'm trying to decide whether to go for it and try setting it up this weekend. Having 3 team mates waiting on you and being towards the sharp end of the race makes these things play on my mind! In the event of changing tyres at short notice between laps (as you sometimes need to at MM when the mud starts sticking!), I presume it's straight forward to switch to tubes rather than mucking about?

Also- do you keep the original rim strip in place and put the tubeless rim strip over the top? If not surely you will puncture the new tube when you install it straight onto the rim- or do you put a different layer of tape down under the rim strip

With mine I've just got the normal cloth rim tape that you use with tubes, then the BMX inner tube.

It all depends how you do it. If you get the Stan's kit, you start with the bare rim, but the yellow tape down which seals the spoke holes, then stretch their rimstrip over the rim, put tyre on and inflate. Ghetto's the same really, but replace "yellow tape" with electrical tape and "their rimstrip" with butchered 20" inner tube.

I've personally just found a selection of tyres to cover all eventualities and conditions that I know will seal with a track pump. In a team of 4 at Mayhem you likely have about 2.5 hours at least to change tyres, there's not a huge time constraint!

FWIW I'm usually near the 'sharp end' in these things too, although I'm not sure what difference that makes, if the technology's good enough for the top pros in the world it's good enough for a slow poke like me! You're less likely to flat than you are with tubes.

If you want to switch to tubes then you have to take your rimstrip out, it's a bit of a faff, but not a major issue.

Flopppy tires should be fine, put on Racing Ralfs which were much more "floppy" than my previous tire Small Block 8's, just needed a lot of washing up liquid to get it seated. (neither of which were UST)

You'll need to do the old sloshing of sealant around the tire wall technique to stop any seeping air but once done should be fine.

I keep spare tubes with me on all rides/races just in case! But not had any major issues, during races.

Kendas are terrible for ghetto.

If it's too lose the air will just escape under the bead before the tyre seats, the tighter the tyre (within reason) the easier it will inflate.

if your planning on changing tyres regularly I would nt bother. Especially at Mayhem, what you need to do is buy a second set of cheap wheels and stick your mud tyres on them.

This will save you loads of agro at MM. Its not like your need a set of racing wheels when the mud really get going as your be carrying your bike anyhow.

Cheers Nick (its Chris / Matlock by the way- probably raced with you but not for a while). I'm not going ghetto- sod that for a game of faffing! I wasnt meaning to willy wave btw- but it is a consideration at team events that your kit is tried and trusted- as you've pointed out. I'll be taking small block8 s, Nobby Nics and continental 1.5s to cover the eventualities…

Ahh… yes, been a while.

Nics will be fine, I personally run Black Shark Muds in a 1.5" when it gets really muddy, and they work fine, although IIRC Conti XCs did also work alright. Not tried the Kendas, so can't really comment.

The Stan's kits are good, as I say the main consideration I'd make is that you may need a few extra turns of tape (electrical will work if you've not got enough of the Stan's stuff) to make the tyres tighter.