Gluing tubs

earth

When mounting a tub to the rim, the first 2/3rds are easy but just as with a clincher the last 20 cms don't want to seat because the tyre needs to stretch over the rim. With a clincher it's just a case of building those thumb muscles but with a tub the problem is the tyre pushes all the glue off the rim, onto the braking track and all over the side wall of the tyre, leaving little glue on the rim. Does anyone have a technique to avoid this? There's a market for some kind of nifty device that would stretch the tyre while you manoeuvre it in place before releasing it onto the rim.

Matthewfalle

some people run a pencil betwixt tyre and rim when fitting.

use it as a lever at ehd.

or pre-stretch tub before final fitting.

earth

Matthewfalle wrote:

some people run a pencil betwixt tyre and rim when fitting.

use it as a lever at ehd.

or pre-stretch tub before final fitting.

I pre-stretch them but the pencil sounds like it might help.

imposter2.0

earth wrote:

When mounting a tub to the rim, the first 2/3rds are easy but just as with a clincher the last 20 cms don't want to seat because the tyre needs to stretch over the rim. With a clincher it's just a case of building those thumb muscles but with a tub the problem is the tyre pushes all the glue off the rim, onto the braking track and all over the side wall of the tyre, leaving little glue on the rim. Does anyone have a technique to avoid this? There's a market for some kind of nifty device that would stretch the tyre while you manoeuvre it in place before releasing it onto the rim.

Got to say, this has never been my experience when gluing. How much glue are you using? Assuming you are pre-stretching the tubs (Contis in particular need pre-stretching) and assuming you are properly stretching them over the first 2/3, then they should never need to be forced over the final third.

Also, the pencil thing works fine for tape - it will just make a very sticky mess if you use one with glue on the rim bed. Just put about 20psi in the (stretched) tub before fitting, ie just enough for the tub to hold shape, and it ought to be very easy. When it's on, work it into shape, add a bit more pressure, work the wobbles out with your fingers/thumbs/rolling it on the floor, then when you're happy, leave it to set.

earth

Imposter wrote:

earth wrote:

When mounting a tub to the rim, the first 2/3rds are easy but just as with a clincher the last 20 cms don't want to seat because the tyre needs to stretch over the rim. With a clincher it's just a case of building those thumb muscles but with a tub the problem is the tyre pushes all the glue off the rim, onto the braking track and all over the side wall of the tyre, leaving little glue on the rim. Does anyone have a technique to avoid this? There's a market for some kind of nifty device that would stretch the tyre while you manoeuvre it in place before releasing it onto the rim.

Got to say, this has never been my experience when gluing. How much glue are you using? Assuming you are pre-stretching the tubs (Contis in particular need pre-stretching) and assuming you are properly stretching them over the first 2/3, then they should never need to be forced over the final third.

Also, the pencil thing works fine for tape - it will just make a very sticky mess if you use one with glue.

I do pre-stretch them. This one will be stretched for a few days due to delays. As for glue I use 2 layers on the rim with a day between each, a layer on the tape with a day for drying. Then on the day I mount the tyre a layer on the rim, 10 minutes until its tacky then I mount the tyre. I guess what you are saying is I should do everything to stretch the tyre as I put it on. This I don't find easy because its awkward while holding the wheel. I could try putting into the turbo trainer after the first 2/3rds are done. Then the turbo can hold it while I manhandle the tyre.

imposter2.0

I fit the tyre as soon as I've finished with the brush. Standing with the wheel in front of you and the valve hole at 12. Valve in the hole and then pull both sides of the tyre down hard from the 10/2 and then the 3/9 position as you go. If the tyre is properly stretched in this way, fitting the final third will be no problem. It will also reduce the amount of vertical roll-out you might get if the tyre tension is not uniform all the way round.

earth

Imposter wrote:

I fit the tyre as soon as I've finished with the brush. Standing with the wheel in front of you and the valve hole at 12. Valve in the hole and then pull both sides of the tyre down hard from the 10/2 and then the 3/9 position as you go. If the tyre is properly stretched in this way, fitting the final third will be no problem. It will also reduce the amount of vertical roll-out you might get if the tyre tension is not uniform all the way round.

So you have the valve on the far side, put that in first and pull towards you rather than valve on the near side and push. I'll try it.

imposter2.0

No, the wheel is standing vertical, on the floor in front of you with the valve at the top (ie 12). Valve in first, then pull from 10/2 (or even 11/1), then 3/9 and then 8/4 and the rest should be no real issue. A lot of people go straight to 3/9 when fitting a tub, which is where it all goes wrong afterwards.

earth

Imposter wrote:

No, the wheel is standing vertical, on the floor in front of you with the valve at the top (ie 12). Valve in first, then pull from 10/2 (or even 11/1), then 3/9 and then 8/4 and the rest should be no real issue. A lot of people go straight to 3/9 when fitting a tub, which is where it all goes wrong afterwards.

And I guess you have to lift it off the floor for the last 5/7.

imposter2.0

earth wrote:

Imposter wrote:

No, the wheel is standing vertical, on the floor in front of you with the valve at the top (ie 12). Valve in first, then pull from 10/2 (or even 11/1), then 3/9 and then 8/4 and the rest should be no real issue. A lot of people go straight to 3/9 when fitting a tub, which is where it all goes wrong afterwards.

And I guess you have to lift it off the floor for the last 5/7.

Yeas, basically, the last third of the tyre is done squatting on the floor with the wheel in your lap, so the final third is at 6 - ie furthest away.

Don't wear your best suit..

earth

Imposter wrote:

earth wrote:

Imposter wrote:

No, the wheel is standing vertical, on the floor in front of you with the valve at the top (ie 12). Valve in first, then pull from 10/2 (or even 11/1), then 3/9 and then 8/4 and the rest should be no real issue. A lot of people go straight to 3/9 when fitting a tub, which is where it all goes wrong afterwards.

And I guess you have to lift it off the floor for the last 5/7.

Yeas, basically, the last third of the tyre is done squatting on the floor with the wheel in your lap, so the final third is at 6 - ie furthest away.

Don't wear your best suit..

I tried it this way and it worked a treat.

pippi_langsamer-2

Conti' Comps are work of the devil for getting on, and no amount of stretching seems to help!

For this reason, I fully mask my carbon rims with electrical tape right up to the lip of the brake track, as it tends to be a very messy affair as I roll around the garage like Steve Irwin wrestling an Anaconda.

I actually do the masking prior to gluing, as it means I can be a bit more slap-happy with the glue. The stretchy nature of electrical tape means you can deform the tape around the circumference of the rim nicely, and it peels off nicely once the job is done.

And yes, I tend to use some kind of leverage device for the last part, but it certainly isn't a pencil for the Conti's!

cycleclinic

Chase the slack like when fitting a tight clinchers that help remove high and low spots too and wobble. The tub then mounts more easily. Pre stretching helps but it's not essential.

Some times I think I am the only one who does lot struggle with tyre fitting.

I only mount a tub once the glue has been left to fry overnight. He bond that results is firm. Vittoria mastik one always too. Tub mounting is easy. Nothing difficult about mounting a conti tub.

I am I the only one on this forum who find mounting tyre easy. Snowflakes I say (only joking). There must be tricks your missing. Drop by and I'll show you.

Alejandrosdog

thecycleclinic wrote:

Chase the slack like when fitting a tight clinchers that help remove high and low spots too and wobble. The tub then mounts more easily. Pre stretching helps but it's not essential.

Some times I think I am the only one who does lot struggle with tyre fitting.

I only mount a tub once the glue has been left to fry overnight. He bond that results is firm. Vittoria mastik one always too. Tub mounting is easy. Nothing difficult about mounting a conti tub.

I am I the only one on this forum who find mounting tyre easy. Snowflakes I say (only joking). There must be tricks your missing. Drop by and I'll show you.

#prothumbs innit.

cycleclinic

Practice makes perfect. I have had slot of practice mostly on my own bikes with tubs as not many people use them any more. It's a shame because tubular are structurally better than clincher rims.

Its not pro thumbs it knowing how to use them. When I see most people mounting tyres it's hire obvious why they struggle. The hands might a well be prosthetics for all the effective use they are making of the flexible digits. This is experienced cyclist too.

Many people think because they can't do something there has to be something wrong with the product. This does relate to the op of the op question now. Often products are made with a certain amount of of fitting skill and knowledge assumed. If your going to be a home mechanic then you have to learn those skill and get those pro thumbs because making products easy for the unskilled to fit in many cases compromises there function.