Leaky front tire, Stelvio

[CTYANKEE]

2014 Stelvio, 250 miles. I was going for a ride, checked the pressure in front, and in two weeks it went from 40 to 22psi.
I haven't hit any big bumps, there's no foreign object in the tire, and as you can see, bike is practically new. Any ideas on what to look for how to check/ what it might be etc?

Thanks

[BMWDavid]

Other than the obvious nails or screws I'd check the valve stem core. Be sure its screwed in snugly. I've had numerous slow leaks on cars and bikes that turned out to be a loose valve core.

[cloudbase]

Another possibility is a leaking o-ring on one or more of the spokes.

You can test by submerging parts of the rim or using a soap solution sprayed on the suspected area.

[Kiwi_Roy]

I believe you have the tubeless rims, each spoke is sealed by an "O" ring, perhaps one of those is leaking.

Is it still under warrantee?

Otherwise a sealant like Slime perhaps

[CTYANKEE]

thanks all, yes, still under warranty, bought last October. I wasn't sure if this is a warranty item.

[Wayne Orwig]

thanks all, yes, still under warranty, bought last October. I wasn't sure if this is a warranty item.

A couple of people have had the O-rings on the spoke nipples leak like that. Find it with some soapy water. Not hard to fix. Should be a warranty item. But you may have something in the tire too. So I would track it down before contacting the dealer.

[motrhead]

What kind of tire? I had a Heidenau K60 Scout installed by the dealer, and about 300km into the trip home, in the dark, it went flat...adventure ensued, but for the next few weeks it was fine and maintained pressure...until about 1000km into my trip to Inuvik, when the tire began to howl because the pressure had leaked down to 20psi, the center blocks were worn to wedges, and raising the pressure back up couldn't save the tire. I swapped it for a TKC80 in Whitehorse, as one face of the center blocks was down to the level of the carcass (wedge shaped) and I couldn't see it making it to Dawson City, let alone up the Dempster and back!  I got about 3500km out of the K60. The TKC80 has held pressure just fine...and has about 6500km on it already.

[Lannis]

Another possibility is a leaking o-ring on one or more of the spokes.

You can test by submerging parts of the rim or using a soap solution sprayed on the suspected area.

Mine was leaking just like that.   Easy to find the offending spokes with soap solution.   I bought a handful of o-rings, nipples, and split rings from Harper's and will just repair the ones that need it at each tire change.

Lannis

[CTYANKEE]

thanks, will try the soap thing. It's a stock tire, believe it's pirelli scorpions, but I'm at work so I cannot check.

[fotoguzzi]

Does anyone else think sealing each spoke with an o ring is a bad idea?

[rocker59]

Does anyone else think sealing each spoke with an o ring is a bad idea?

Alpina has been doing for a long time, and it's been successful with the system.

Supermoto racers use the system quite extensively.

The wheels are much lighter than the EV wheels and the BMW GS wheels.

Everything has its compromises.  I like the external spoke mounting of those German wheels, but the added material to accommodate them makes the rim really heavy.  Just the part of the wheel where weight matters the most.

[mrrick]

This Alpina system looks pretty cool to me, cleaner than gooping up your rims with silicone and duct tape, or whatever, to permit tubeless tire usage.
http://alpinawheelsusa.com/products/motorbike-tubeless-kit-conversion/
Of course, they want you to use their rims, precisely drilled (9mm it seems) to make the o-rings work.
The question I'm interested in: could one successfully modify standard Borrani or other rims, to make it work and not have to buy (Guzzi content) their rims?
Are the Alpina rims perhaps made with an unusual cross-section to permit use of their "security ring", which holds the nipple in place?
 

[Wayne Orwig]

Drilling the tapered holes, getting those spokes with those special nipples all to be right. Sounds like more pain then just gooping it up.

When I got my Stelvio, that was at the top of my list of worries. I've never had a problem, and the few people that have, simply replaced an oring or two as far as I know. I did oddly break a spoke. The nipple stayed in place and did not leak a bit.

[kirb]

Order up a few nipples (complete) and a few o-rings and carry them with you. Should solve any slow leak problem.

978810 Nipples
AP8101744 Tubeless tyre valve 1
978811 Snap ring 36
GU90706061 O-ring OR2025

[racasey]

What is the role of the split rings?  How is the thread inside the nipple sealed against the threaded spoke?

TIA

Ciao,
Dick

[Phang]

What is the role of the split rings?  How is the thread inside the nipple sealed against the threaded spoke?

TIA

Ciao,
Dick

I think the C clip is to prevent the nipple dislodging from the nipple hole and cause a rapid tyre deflation when a spoke broke.

[Lannis]

What is the role of the split rings?  How is the thread inside the nipple sealed against the threaded spoke?

TIA

Ciao,
Dick

The split ring is there to keep the nipple in place, sealed, and not fall into the tire if the spoke breaks.   Looks like a thin sort of thread-sealer is applied before the nipple is threaded on to the spoke.

The whole thing sounds dodgy, with 40 potential leak-points per wheel, but it also seems to work.

Lannis

[Wayne Orwig]

What is the role of the split rings?  How is the thread inside the nipple sealed against the threaded spoke?

As far as I know the ring keeps it in place and leak free if a spoke breaks. But then when mine broke, the ring never touched the rim from what I could tell.

The nipple is not an open through hole. It is a blind hole, so solid on the inside.