[Closed] 20mm tubeless tape on a 25mm internal rim?

You need wider than the internal cavity width. On a 25mm internal rim, 27mm is the idea width of tape…

Useful chart here on Hunt’s site to help…

https://www.huntbikewheels.com/products/hunt-blackshield-tubeless-rim-tape?variant=12743994441805

Hope that helps.

Might work, but will be easily damaged when removing a tyre and is unlikely to last long

I've done it before where it just covers the spoke holes.. it works but, as above, easy to nick it when removing the tyre.

You could use the narrow tape but do 2 wraps, one to either side of the rim bed.

I can do what @frogstomp suggests as ive got a fair length of it.. will joining in the middle be a problem?

I'd do 3 wraps. One in the middle and one each to either side with 2-4mm up the sidewall.

I do one wrap the go round the lot with lecky tape.

The strength of the tubeless tape is only for the big holes.

will joining in the middle be a problem?

Well, there'll still be an edge that the bead can catch on when you take the tyre off.

I got away with tape that was too narrow for a while, until I left the wheels in the car on a warm day and the tape lifted. If you use tape that's wide enough, there are no edges that can lift and let air out because the tape is pinned down by the tyre beads.

Interesting discussion.
In the old days before "tubless rims" the tape would go full width to help seating.
Nowadays I just use tape to cover the holes, so prefer narrow over wide any day. I have never had a seatng issue or any tape issues using this method for the last 4-5 years.
Why does the tape need to be wider?

Is the rim welded or sleeved? If it's sleeved and the rim taoe is too narrow you could get a leak at the rim join.

leak at the rim join.

Milk fixes this in minutes though.

Cheers for link mboy 👍
Need to try again with wider tape 🙈😂

You need wider than the internal cavity width. On a 25mm internal rim, 27mm is the idea width of tape…

I know you used to be a bike mechanic.

But I have never put tape on that's wider than the spoke hole bed and never had any issue other than the odd edge lifting that I have sorted with electrical tape. What benefit is waiting for extra width if it's not actually necessary? As long as the spoke holes are covered obviously.

Depends on the rims. My current Sonder Alphas came with a thun tape up the middle just covering spoke holes and they up tubeless without issue. WTB rims however have given me grief if they aren't 5mm wider than the internal width.

Why does the tape need to be wider?

If the tape covers the full width of the rim, the seal is formed completely between the tyre and the tape, so it doesn't matter how well the tape is stuck to the rim, and there's no way that it can lift. It also doesn't matter if the rim joint is sealed, because the rim isn't exposed to the air in the tyre.

It also avoids the problem of the bead catching the edge of the tape when you remove the tyre.

How much of a problem any of this is will depend on how tight your tyres are, how often you remove them, where exactly the edge of your narrow tape falls, and how leaky the rim joint is. Using tape that's wide enough avoids a load of possible problems, but that doesn't mean that narrow tape can't work.

It'll work fine as long as they're sealed/welded rims. It'll not be ideal since as mentioned above, when you change tyres you're much more likely to damage it. But that's a problem for the future.

joshvegas
Free Member

But I have never put tape on that’s wider than the spoke hole bed and never had any issue other than the odd edge lifting that I have sorted with electrical tape. What benefit is waiting for extra width if it’s not actually necessary?

So basically 2 answers. The first is, not all rims are sealed so if you don't tape to the edge they leak- mostly cheaper pinned ones, quality rims are almost always welded and fully sealed.

The second is, as above if your tape goes up onto the raised part of the rim, but not all the way to the edge, then it's likely to get pushed off when you change tyres.

So really it's all about the rim. But whenever possible I do it like you describe- tape the middle, not the sides. Modern rims being so wide you can generally do this and just tape the well in the middle, and that way you get a perfect seal but also, it's immune to being damaged by the tyre as it's sunk away. Absolute best of all worlds ime but it'll just not work on some rims.

Yeah so its just about unsealed rims and those problems are always fixed by milk.

Not for me. The thing that convinced me to always do full width was when the tape lifted when left in a car on a warm day. With narrow tape, you're relying on the adhesive to seal the tape to the rim. With full width tape, the tape doesn't need to be sealed to the rim, only to the tyre.

Yeah so its just about unsealed rims and those problems are always fixed by milk.

Well, it is I suppose, apart from all the other reasons

Well, it is I suppose, apart from all the other reasons

...and as with my experience with WTB rims, the sealant doesn't solve it and you just fill your rims with goop that leaks out of the spoke holes.

So in the end i put a strip over the spoke holes and a strip from either side so covered every base. Tried to seat tyre and air is coming out of the valve hole.. 🙁

@ turbo1397,

If you like, DM me your postal address. I've got an un-used roll of Stans' finest brittle yellow rim tape in 25mm flavour (although as has been said above, you might want 27mm tape for a 25mm rim)

Oh, never realised this was such a big deal. I always just used whatever I had to hand, always a bit narrower than rim and never had problems. Only issue I had was when I tried gorilla tape once and it did come away at the edges. Live and learn…(or not, as I’ll probably keep doing what has worked for years)