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Quick and kinda urgent question - tubeless conversion

KameramanDan's picture

By KameramanDan - Posted on 17 October 2014

NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.

Hey guys, pulled my tyres off to do a tubeless conversion, and am a bit stuck. I've never even seen the inside of a rim before so this may be a massively stupid question, but I don't want to proceed til I've got an answer.

I have the notubes sealant, valves and a roll of 25mm rim tape. My rims are 20mm (flat bit in the centre, not outside width) and I'm fitting a Minion to the front, High Roller to the rear.

My rims are double walled (not sure if all rims are like this or not) and so there are two holes for the valve, one in the outer wall (the wall the tube rests on) and one in the inner wall (the one closest to the hub). There are small holes in the inner wall that look like they are there to allow air to flow in and out from the tyre chamber as the tyre flexes around the tube.

I was following this video:

...they have a similar setup and it appears they seat the valve on the outer wall but they also fit a rubber rim strip which looks like it would seal up the small holes.

I don't have a rim strip; LBS said they don't use one in these setups. Do I seat the valve on the outer wall (the one the tube would rest on - as per the attached photo) and cover the holes with tape or do I enlarge the outer hole so the valve seats on the inner wall (nearest the hub) and therefore the chamber between the two walls is pressurised?

Or a third option?


fairy1's picture

I thought the little holes would have been at the joint but they are all the way around, never seen that before. Is that an old Dirt Bag rim?

I would think it would be almost impossible to make that work well as a tubeless wheel.

EDIT- I'm an idiot, you could still do the ghetto tubeless setup with a stretched BMX tube.

DOUBLE EDIT, My brain is fried, If those holes just go in to a hollow void in the rim it might work fine but you will lose your goo in to them so running some neutral cure silicone over them could be a good idea.

Ian_A's picture

I have only ever used Bontrager rim strips because they worked so well the first time I set them up.

Tape first then carefully poke the valve through. Maybe poke a nail through first.

CyclinAl's picture

If they don't lead to the outside of the rim through other holes, they shouldn't pose too much of a problem I would think.
1- It looks as though they'll be partially covered by the tyre bead when it's seated.
2- If they don't lead outside the rim, they won't create a leak as such. That space they lead to will just pressurize to the same level as the tyre.
The problem with trying to tape them, I think, is that it's likely to interfere with the bead trying to seat onto the rim.

CyclinAl's picture

Actually, why don't you fit your tyre, using a tube.
Then deflate, pop one bead.
Remove the tube.
Have a look at how much of the little holes are still showing on the bead that's still seated, if any.
The less, the better I guess.
And regarding the valve. That's pretty standard: Run the tape over the spoke nut wells making sure it overlaps on either side. Poke a hole through the tape and insert your valve. DONT enlarge any of the holes.

pharmaboy's picture

Geez, this is getting off topic quick! Eye-wink

Valve goes in the outer hole - when you install t you'll find this is the only way possible anyway. I am making the assumption you have either gorilla tape or stans rim tape for the job - tight is good, one thickness of tape round the rim is enough . Pierce the tape through the valve hole with something like a pen or 2mm Allen key, and as you tighten the valve onto the inside of the rim, the rubber grommet on the end of the valve will make an airtight seal.

KameramanDan's picture

Thanks guys.

To answer your questions:

CyclinAl - Yes the holes lead to outside air. They lead into the chamber between the two walls which leads to atmo.

fairy1 - Yes it's a dirtbag rim. I thought you must have a damn good eye for rims then realised the logo is clear as day in the first pic Eye-wink The holes aren't all the way around but there is also a set directly opposite the valve (on the other side of the rim).

CyclinAl question 2 - I can't really 'pop' a bead, there is no seat for the bead at all so it doesn't sit on anything. I'm new to bikes but I know a thing or two about tyres and I can see that I would be able to push a tyre off these rims with almost no effort.

After a proper look and a think about it I feel like I would need split tubes or go ghetto tubeless. I think I'll return all the bits and run tubes for now.

KameramanDan's picture

So fit the valve to the outer wall, seal the little breather holes on either side of the valve, creating pressure outside the outer wall and no pressure between the inner and outer wall.. yes?

CyclinAl's picture

Or as Bollo the ape of The Mighty Boosh would say:
I got a bad feeling about this...

KameramanDan's picture

AWWWW I love bollo. Thanks for reminding me to download the entire mighty boosh... haven't watched it in AGES but something came up at work the other day about Johnny Twohats and I've been meaning to grab it ever since.

TBH I think I'm just going to return the tubeless stuff (rear shock comes back from a $250 service on Monday so I should be right to get a credit towards that) and stick with tubes.... I had no real reason for going tubeless, I just kinda wanted to do something to the bike over the weekend Sticking out tongue

BUT I will take the rims and stuff in with me tomorrow and have a talk to the guys in the shop, see what they reckon.

Cheers for the help

fairy1's picture

If that is the DH rim it is a seriously heavy beast and you would be better off throwing a lighter rim on. But if you can get your money back on the kit that's probably the best option.

I've done my tubeless on the cheap using a tough masking tape and home made goo, seems to work as well as the Stan's I had before but I haven't had any big holes yet.
I used a mix of Glycol, Latex, glitter, water and Polenta, recipe was thieved from the net somewhere.

KameramanDan's picture

ok to be clear about this I do not want to spend any more on this bike... will ride tubes for years if I have to.

Thought I could go tubeless cheap and it might be a fun couple-of=hour project for a friday night.

Turns out maybe not, happy to just go back to tubes and return the tubeless kit Smiling


hawkeye's picture

Go ghetto tubeless. All you need is a roll of fibreglass strapping tape to cover the spoke holes, a couple of Schwalbe BMX tubes with the removable valves, and some Stan's (or other brand) tubeless sealant.

Those welding vent holes won't be an issue, they will be covered by the tube. However, the narrow shoulder on the rim bead seat may mean you need to make a ghetto compressor out of a 2litre fizzy drink bottle to dump the air in there fast enough to make it bead up. Or if you have a decent home compressor use that.

CyclinAl's picture

Fairy1, Ok that's your Carb Loading taken care of. But what do you put in your tubeless tyre? Eye-wink
KameramanDan, sounds like a lot of farting around and the reliability may be a bit uncertain. The benefits of tubeless are pretty compelling though so why don't you run tubes in your current rims and keep a lookout for a cheap set of tubeless rims. Maybe set up each set of rims with different characteristics tyres and use them to suit the conditions. I'm sure a preference will develop from that comparison.
Just don't come too close to the edge if you ride Manly Dam mate. I hear Old Greg has his summer residence there. You really don't want to see his mangina...

Scottboy's picture

I told you to get a couple of 20inch tubes and go ghetto using them all should work .

lorax's picture

The reason you drill the valve hole is to help the valve seat properly. I have double walled rims and drilled through both walls and everything works fine. You could just drill out the inner wall and it would work just the same. I have the Stans universal tubeless kit with the valve integrated with the rubber rim tape. These work a treat. My rims aren't made for tubeless. Don't return the kit, do the conversion, you'll spend heaps more time riding rather than fixing flats. Use 2 cups of goo and check/refill every 6 months.

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