I like the look (and price) of the new Shimano MT66 wheels so much that I’m thinking of taking the plunge at last and going tubeless.

But can someone explain to me whether running UST rims and UST tyres I still need the sticky white goo stuff, or is that only necessary to help ‘tubeless ready’ conversions seal properly?

TBH its the messy goo thats put me off tubeless so far, so I’d rather do without it if its not necessary with a full UST setup.

you need the goo if you don’t want the first thorn that goes through the tyre to let all the air out.

you need the goo if you don’t want the first thorn that goes through the tyre to let all the air out

Good point, but where I ride I’ve never had a ‘normal’ puncture, only pinch flats, so I wouldn’t use goo just for puncture protection, only if its necessary to get the trye & valve to seal properly. Or are the UST tyres more prone to punctures for some reason?

no more prone than any other tyre – they tend to have slightly better puncture resistance I think.

I run UST rims and tyres with the goo. No hassle, just check and top up twice a year (unseat one of the beads and check inside). No punctures for two years (which of course means I’ll get one this weekend).

Use the goo. Daft not to. It is no problem.

but where I ride I’ve never had a ‘normal’ puncture,

Well that’s a puncture guaranteed the next time you go out 😀

Also the goo will help get it sealed in the first place.

PS. follow all the hints like fitting with a normal tube to start with.

JRA wheel milk is my goo of choice.
Cheap and works. Cycle surgery sell a syringe thing with car valve on end. makes squirting in very easy and tidy.

Use the goo. Daft not to. It is no problem.

+1

def use the goo., it’s not difficult.

Thanks guys – can’t help noticing the theme here is to “use the goo, daft not to”, but why is that?

Is it for puncture protection or to help the bead seat and seal? As I said, the first isn’t much of a reason for me, but the second could be. However, I thought ‘true’ UST rims & tyres weren’t supposed to need this – afterall we don’t run goo in our car tyres, and I don’t see many of them having burping problems!

I just that I don’t see the point of messing around with the sticky stuff if it isn’t necessary – but willing to be persuaded if someone can convince me of a real benefit…

‘Normal’ tyres and goo for lighter wheels?

Is it for puncture protection or to help the bead seat and seal

Both.

It’s really no issue sticking 60ml of slime in before you inflate, why run the risk of running over a thorn and not having protection? Makes almost no sense.

For me, the peace of mind offered in having an almost leakproof tyre seal, all year round, outweighs any of the fussing around

willing to be persuaded if someone can convince me of a real benefit…

the slightly smug feeling when you literally hear your tyre puncture, hiss for a second or two, then seal itself of its own accord.

My understanding was UST Tyres and Rims don’t need the goo (UST Tyres being thicker to prevent reduce the number of punctures, and UST rims having a better seal).

As others have said, might as well put some goo in there to seal any punctures you might get, or you could try without and see how you get on?

/\ that’s true enough, but with slime you can also easily run 99% of non-UST tyres.. they are lighter and you will notice the difference when riding.

it’s sexy.

Also the goo will help get it sealed in the first place.

PS. follow all the hints like fitting with a normal tube to start with.

That’s totally irrelevant with proper UST. They go on and seal with just a track pump with no sealant and no pissing about.

As for the original question: no they work fine without sealant. Only add it to protect against thorn style puntures.

Get a proper UST repair kit though (especially if not using sealant): one of the string ones like the Weldtite one. If you do get a puncture it’s then a doddle to fix.

/\ that’s true enough, but with slime you can also easily run 99% of non-UST tyres.. they are lighter and you will notice the difference when riding.

it’s sexy.

And they burp more easily…

For the OP, if you never ever get thorn punctures, then fair enough, go UST without any sealant in. Before Stans was big, I ran UST rims and tyres for a couple of years, without sealant. Never really had any problems as such, but yes, they are susceptible to thorn punctures like that.

Almost all of my punctures used to be pinch punctures rather than thorn punctures, due to how I rode and where I was riding, and UST solved that even running dry. UST tyres are a bit thicker anyway, so they’re more puncture resistant as is, though only slightly. If a thorn wants to go through it, it will, and then you’ve either got to patch the tyre from the inside (or more likely just put a tube in it track side after removing the thorn), or run some sealant anyway.

FWIW, I’ve tried almost every combination you can think of regarding rims and tyres for compatibility tubeless wise, over a period of about 9 years. I’ve come to the conclusion that proper tubeless tyres are the answer for reliability purposes, no matter what rims you run, and that even in a full UST system a small amount of sealant (you won’t need much at all) makes sense just in case you do get a thorn puncture. I’ve changed tyres before and noticed embedded thorns inside the tyre when I’ve removed it, and wondered how long they’d been in there, and how each one of them would have caused me grief had I not been running any sealant!

But if you think you’ll never ride over a thorn, go dry… It works fine as long as you use UST tyres on UST rims and make sure you inflate them up to like 50-60psi first (to get the bead to seal properly) before letting them down to your preferred pressure.

Great, thanks – that starting to make sense now!

Now can’t wait until the new MT66 wheels hit the stores 😀

these are nice and cheap right now at Merlin, any good as all round XC/AM wheels, or weak, or some catch? can be run well tubed and tubeless? only 24 spokes hmm.

Hi Smiff, noticed you resurrected my old thread!

I didn’t go for the MT66 in the end. I found out they’re kinda a halfway house between full UST (like the XT wheels) and conversions like stans. Even though they have a UST rim profile, the spokes still penetrate the rim and they come with rubber caps to seal the holes, rim tape and sealant.

I decided to spend a few more pennies and get the XT M785 instead, and I haven’t been disappointed – like I expected, and others said above, with ‘proper’ UST rims and tyres its a piece of p1ss to install and ride. Only downside I can see for a full UST setup over a conversion is that the conversion is lighter. But saving weight wasn’t why I went tubeless, and I love the no-hassle factor of the proper UST system. And no, I didn’t go with goo in the end either…

PS: If you’re worried about the strength of the MT66, might be worth waiting until the MT68 come out, as they are more of an AM wheel with a slightly wider rim (same as the difference between M785 and M788 wheels in the XT lineup).

thanks good info, the m785 seems to be £100 more now though (or if you like 10,000p :/), so that’s a different market really..
maybe these then:
http://www.merlincycles.com/bike-shop/wheels/mountain-bike-wheels/factory-mountain-bike-wheels/mavic-crossride-disc-wheels-2013-pair.html
the shimano ones still look a deal though. if i was paying £250 ish i’d being going for Hope.

Crossride aren’t UST though, so if you ever want to go tubeless with them you’re back to all the problems of compressors, goo, rim strips, burping etc.

The benefit of a proper UST profile rim is threefold:-

1. Inside the rim has ‘shoulders’ that the tyre beads sit on and effectively makes an airtight seal even before they’re inflated. So then you can pump them up with a normal pump. This is what causes the most issues when you try and convert a normal rim to tubeless, the lack of this shoulder and the problems this causes getting the tyres to seat initially.

2. A proper UST rim is sealed on the inside – the spokes don’t penetrate the inner rim, so you don’t need rim strips and sealant to get an airtight seal.

3. UST rims have a different bead hook, which matches the different bead of a proper UST tyre, so that the tyres seal and ‘lock’ into the bead hook. In fact, even after deflating a UST tyre, you have to push the bead out with your fingers to get the tyres off, as they lock in so well!

You can see each of these features in this diagram

Normal rims like the Crossride don’t have these features, and therefore need to be ‘converted’ to tubeless with rim strips, sealant etc, but can still be prone to problems like not seating easily without a compressor, losing air, burping etc.

The MT66 has the shoulders and bead hook of a proper UST rim, but you still need to use rim tape and sealant to seal the spoke holes – but they are about teh cheapest way of getting a UST rim.

Full UST rims like the XT have all these features, but the downside is the extra metal in the rim, and extra rubber in the tyres, makes them heavier than a conversion, and yes they are more expensive. For me, this was an acceptable tradeoff, but YMMV.