Alright Single Trackers! Did not bad at the Full Beam Day/Night Mini DH at Innerleithen on Saturday on my Five (placed 13th out of 29).

On my final, fastest run everything was perfect. Well quick. Then my rear tyre came off the rim after one of the bottom jumps into a fast berm (part of Matador I think). Raging.

I’m pretty sure it was the speed and sidewaysness of my bike round berm that caused it. I ride DH at Inners loads and loads on my Five and this has never happened before.

I’m running a 2.35 60a Minion DHr. Which is ideal in terms of grip/shredding-ability. It’s on a UST 819 rim. However the tyre is not UST.

This was my first race and I really don’t want it to happen again. So.. should I:

a) Stop running tubeless to race DH on a trail bike, ya fanny!

b) Get a UST Minion.

c) Stop moaning and accept it happens to everyone and crap-luck is part of racing

Thanks!

b) Fit a UST tyre

B & C, definitely. I had a similar thing happen to me racing at Ft Bill in 2008, except it was my front tyre. Minion on a Mavic rim with stans tubeless conversion. Non UST Tyre and Rim, running around 25psi, it was asking for trouble really.

Life goes on…

a

B)

DOH!

The key to successful tubeless, as I keep pointing out to anyone/everyone who has failures, is running proper tubeless tyres… The rim and the tubeless method you use is almost totally irrelevant, it’s the use of proper tubeless tyres that matters!

Wait until wednesday. The laws of physics are getting a service update to address gnarr-bugs like this. Once updated going dead fast round corners will be fine.

I think your rims are too narrow.

d) fit wider rims

c)

Now and again stuff’s gonna go wrong.

I’d suggest looking at tyre pressure – I use non UST Minions tubeless and have no problem with them – but I run at 35PSI as below that, it just feels all wrong and squirmy.

d) +1.

819’s are rated by Mavic for tyres between 1.50 to 2.30. You’re outside that range already, and IMO that range is marking out what the rim can handle with *moderate* use, not full-on downhill gnar.

Thanks for all the responses!

Wait until wednesday. The laws of physics are getting a service update to address gnarr-bugs like this. Once updated going dead fast round corners will be fine.

I’m running a pirated copy of physics so I don’t receive updates.

I run my rear tyre somewhere around 30psi according to my ancient EBC track pump…

To be honest the rim is knackered so looking to replace it anyway. I’ll take all this great advice on board and will:

1. Get a UST Minion.

2. Get a wider UST rim. I prefer the Mavic tubeless system over Stan’s so EX 823 I guess.

3. Run the tyre a bit harder.

4. Stop moaning!

C & d also it wasn’t your fastest run as the time at the end is used to measure that

819 definitely too narrow for 2.35s at low pressure.

I’ve done the same thing numerous times(and on the front, proper scary!), max I would run is 2.1 if going <30psi

wider rim, or smaller tyre, or more pressure

I’m not a downhiller so probably don’t ride fast enough for this to be relevant, but I have run super tacky minions on my five (819s) on a trip to the sierra nevada and had no problems at all. 2.35 USTs at 25-30 PSI on some pretty terrifying and rocky descents.

(They’re still in the garage if you want to buy them, mail me for pics etc.)

What pressure were your running? Sounds like it was probably too low for your “fastest run” gnar level

Edit: tyre size is fine. Everyone knows the Maxxis measuring tape is wonky

Rim too narrow! So d).

I’m running a pirated copy of physics so I don’t receive updates.

😀

I’ve had success running Maxxis UST tyres on Stans Rims. Easy to fit and inflate with just a track pump and no leakage once sealed with fluid.

I had the same problem with 2.35 minion rear, fine for cross country but a little unreliable for down hill (especially for heavy sideways landings which are my speciality).

I’m on 2.5 UST now and they have survived all sorts of incidents.

and you do need a wider rim, perhaps a chance to run big tyres on a wide rim a lighter tyres on your 819s?

What pressure were your running? Sounds like it was probably too low for your “fastest run” gnar level

Somewhere around 30psi according to my crap pump.

I’ve had success running Maxxis UST tyres on Stans Rims. Easy to fit and inflate with just a track pump and no leakage once sealed with fluid.

I use Stan’s rims on my hardtail. I have a 2L coke bottle inflatermajig so seating tyres isn’t an issue. I just prefer the Mavic system ’cause there’s no faffing with tape. Stan’s rims are a fair bit lighter but I’m not too bothered about that.

I have rolled lots of tyres off the rim, when running below 30psi. If you run low pressures then you take the risk of rolling them.

Doesn’t matter if the tyre is UST or not. Below 30 psi there is simply not enough pressure to hold it on the rim.

if you dont like faffing with yellow tape I think the new flow EX have a sealed rim bed like mavic 819s

Could the answer not be j) you punctured and that why the tyre came off the rim?

For a downhill trakc surely its h) run dual ply tyres

not many people run tubeless for dh. because the cornering is so hard it’s just unreliable.

if you dont like faffing with yellow tape I think the new flow EX have a sealed rim bed like mavic 819s

Nope, you still need yellow tape as a minimum.

b) Fit a UST tyre

+1

swingbin – are you sure re: yellow tape? I got this from JRA website:

“No need for a rim strip – just use the Universal valve”

http://www.justridingalong.com/wheel-parts/rims/flow-ex.html

I took that to mean it was fully sealed, like mavic

nosedive – Yep sure.
Straight from the Stans website – “Fully tubeless compatible with the 25mm yellow tape and valve stem.”

I also have these rims. They are very much the same as the Arch Ex but quite a bit wider.

Slight slip up from JRA I think, no need for a rim strip, yes, but still need for a rim tape.

I’m running a pirated copy of physics so I don’t receive updates.

then come Weds you’re in for a world of pain

[video]http://www.youtube.com/watch?v=vfl33Tn0pYc&feature=relmfu[/video]

Wider rim…tyre possibly rolled off rim…

Markie – Member

d) +1.

819’s are rated by Mavic for tyres between 1.50 to 2.30. You’re outside that range already,

No he isn’t, it’s a Maxxis 2.35 therefore well within the limits of a 819.

I’m going to go for e) It hasn’t happened before and might never happen again, so don’t freak out over a one-off.

I went for e) when it happened to me. I was really annoyed when it happened again the week after.

Pretty confused. Don’t want to throw money at a problem that is just down to crap-luck / my stupidity.

Short-term I’ll try running my tyres a bit harder and hope it doesn’t happen again. Long term I’ll get a wider rim and UST tyre.

Riding Dunkeld this weekend – if it’s going to happen again it’ll happen there.

I’d certainly say b), a bit of c) and maybe if you intend to do more DH racing/riding f) – consider buying a cheap used DH bike to save your Trail bike from getting battered (I think d) and e) are taken now)…

Short-term I’ll try running my tyres a bit harder and hope it doesn’t happen again. Long term I’ll get a wider rim and UST tyre.

Put a medium weight tube back in would be the easiest short term solution with a standard tyre – if you don’t want a repeat roll-off.

Stans Flow Ex would be my rim choice for running tubless – nice wide + low profile. Once the yellow tape is on tubeless is a doddle.

To finish first, first you must finish. Maybe learn a wee bit of mechanical sympathy?

I’m running a 2.35 60a Minion DHr

so nowhere near proper 2.35.

Swing bin got a flow ex at home, I quite assure you it’s got loads of holes in it. Yellow tape needed. IIRC EX rims are recommended not to use UST tyres as they are just too tight a fit.

Oh and I did once burp a UST tyre on a UST rim, but that was a 2.5 on an 819 at low pressure so fair enough I guess.

Riding Dunkeld this weekend – if it’s going to happen again it’ll happen there.

Not unless Dunkeld suddenly has new high speed berms that I don’t know about. Cornering loads are totally different to what a rock garden dishes out – you are however very likely to puncture a single-ply up there. Thinking about it, I’m not sure I’d bother riding Dunkeld without dual-plys

D0NK – you’re preaching to the converted!

Northwind, I understand you’re saying the tyre in question is less than 2.3 in reality, but I still think it’s marginal at best and that the narrow rim is the main reason for the OP’s problem.

D0NK – you’re preaching to the converted!

sorry, i reread it, it was nosedive who wasn’t sure about flow ex, doh!