Cycling UK Forum

I've recently started to use Tubular Tyres on 700c wheels - does the adhesion run across the rim (edge to edge) or is it in the centre? They were put on the rims by a LBS who has buiolt several bikes in the past for me.

AlSo is it worth trying to seal any potential gap between the tyres and rim - any recommendations?

Thanks in advance

If you use tubular cement to fix them then you cover the whole surface, which leaves you trying to remove the cement that is squeezed out on inflation. If you use tapes than the tape is one width which is pretty much the width of the rim, and you don't have any mess to clean off.

Gaps between the tyre and the rim

Where?

tatanab wrote:If you use tubular cement to fix them then you cover the whole surface, which leaves you trying to remove the cement that is squeezed out on inflation. If you use tapes than the tape is one width which is pretty much the width of the rim, and you don't have any mess to clean off.

Gaps between the tyre and the rim

Where?

I suspect the OP means 'tubeless'(no inner tubes with 'clincher' tyres) rather than 'tubular'(tyre and tube combined)

^^^ that did cross my mind, but since the question mention adhesion I took that to be a typing error for adhesive. Hence response for tubulars. I could not imagine the use of adhesion/adhesive relating to tubeless. No doubt we will find out.

QUIST wrote:I've recently started to use Tubular Tyres on 700c wheels - does the adhesion run across the rim (edge to edge) or is it in the centre? They were put on the rims by a LBS who has buiolt several bikes in the past for me.

AlSo is it worth trying to seal any potential gap between the tyres and rim - any recommendations?

Thanks in advance

The tub needs to be fully glued edge to edge. If there is a gap, maybe due to the tub not sitting nicely due to the stitched seam, or too narrow tub tape, or too little glue, then I would just take off the tub, clean it all up and start over again. Rolling a tub in a corner is not something to look forward to! Try to roll the fully inflated tub off the rim using your hands, if there is any chance of this happening then don't trust it.

I now use this stuff:-

http://www.chainreactioncycles.com/effe ... prod150152

Have been using it for a little while now. This evening I really struggled to remove a tub that had been glued on for over a year. The glue was still extremely strong and sticky, not dried or brittle anywhere. Finally managed to get a screwdriver shaft under the tub and worked my way around. Need to glue a new tub back on for a race on Friday.

By far the easiest and best way I have experienced to glue a tub. The barrier tape is very strong and there is no chance of ripping it as you peel it away with the tub in place.

The only downside is the price, £10 per wheel!

QUIST wrote:I've recently started to use Tubular Tyres on 700c wheels - does the adhesion run across the rim (edge to edge) or is it in the centre? They were put on the rims by a LBS who has buiolt several bikes in the past for me.

AlSo is it worth trying to seal any potential gap between the tyres and rim - any recommendations?

Thanks in advance

Tubular tyres stay up mainly by adhesion, but also because of their pressure.
Road tubulars on normal road rims for tubular tyres ought to have a good contact, because of the matching radius of the rim to the round profile of the tubular tyre.
Old rims for tubular tyres used an average wider radius than today, so they were more prone to show a gap in their edge. Yet, a job well done get the tubular tyre to stick on most of the rim's width. Modern rims would often get a smaller radius, which in turn means that the tubular tyre can be more difficult to fit, but in this case the adhesion is better.

If you are not sure about the job, try to lift off a portion of the tubular tyre from the rim (use a tyre lever), you want to have adhesion on at least 3/4 of the rim/tyre contact surface, that 1-2mm on the sides does not need to be sealed unless you do CX with wide tyres and low pressure.

I'm not sure why I really stopped using tubs - I still have them on one bike - the exceedingly dry weather Eroica machine. I used to use them for everything except touring year round and when tub tape was launched - manna! I could actually change a tub from halt to back on the move in @ 4 minutes! The tape can last a couple of tyres - liquid cements really should be replaced at every fitting - oh hang on it was the mucking about which caused me to change to open tyres!

I didn't always use a continuous strip of tape - several 2cm gaps - maybe 3 or 4, wouldn't affect riding but could make removal easier particularly on the tighter tubs. Now Wobbly Juniors needed every bit of glue you could fit on the rim they were so slack!

This video shows the correct way to fit. https://www.youtube.com/watch?v=2DLSG2WT0mc It's also advisable to put a couple of layers of glue on the tub and rim and letting it dry between each application if they are new.

pete75 wrote:This video shows the correct way to fit. https://www.youtube.com/watch?v=2DLSG2WT0mc It's also advisable to put a couple of layers of glue on the tub and rim and letting it dry between each application if they are new.

That is exactly how to do it, from pre-stretch of the tyre on the rim, to de-burr the valve hole, and cleaning the contact surface.
I would only add: give a shot with the air-gun to the floor where you're going to lean the rim with the glue, so to remove any dust

foxyrider wrote:...

I didn't always use a continuous strip of tape - several 2cm gaps - maybe 3 or 4, wouldn't affect riding but could make removal easier particularly on the tighter tubs. ...

That is not a good advice.
The tub tyre needs to have 100% adhesion. Do not leave any gaps, it's pointless and can cause tyre wobble and unwanted release in off-camber turns. When you see guys in CX with tubs rolling off, it's because water seeping in between the rim and tyre (thus unbonding), irregular glue disttribution, or the glue was very old.

Gattonero wrote:

foxyrider wrote:...

I didn't always use a continuous strip of tape - several 2cm gaps - maybe 3 or 4, wouldn't affect riding but could make removal easier particularly on the tighter tubs. ...

That is not a good advice.
The tub tyre needs to have 100% adhesion. Do not leave any gaps, it's pointless and can cause tyre wobble and unwanted release in off-camber turns. When you see guys in CX with tubs rolling off, it's because water seeping in between the rim and tyre (thus unbonding), irregular glue disttribution, or the glue was very old.

Don't dis it until you've done it - I used tubs for 20 years and never had one roll. I wasn't offering it as the way to do it, just making an observation as to how you 'can' do things. A gap of 2cm will not make any difference to the overall adhesion - you already have a gap at the valve after all. One advantage of using tape rather than 'glue' is that it doesn't dry out, distribution is always perfect and water seepage isn't an issue i've ever heard of. Just saying.

foxyrider wrote:...

Don't dis it until you've done it - I used tubs for 20 years and never had one roll. I wasn't offering it as the way to do it, just making an observation as to how you 'can' do things. A gap of 2cm will not make any difference to the overall adhesion - you already have a gap at the valve after all. One advantage of using tape rather than 'glue' is that it doesn't dry out, distribution is always perfect and water seepage isn't an issue i've ever heard of. Just saying.

I install about 100 tubulars per year, by two decades.
There's no reason to leave gaps, the tub has to be glued to stay there, not to make the removal easier.
Some particular situations, like CX where the very low pressure makes the bonding critical, to leave gaps is only looking for trouble and I do not advise to do so.

I haven't used tubs for years.

I started using tub tape when it first became widely available. Shortly afterwards I moved to Spain and started to experience the tub rotating on the front rim under braking. If I didn't stop and reverse the front wheel in the dropouts from time to time the tube would fail around the valve. I put it down to the higher ambient temperatures and the heat generated from braking on long alpine style descents. Does anyone know if this is still a problem with modern tub tapes?

On long descents with the brakes full on and hot climate, the tub can rotate whether you have it glued or taped.
It is obviously related to the rider's weight, the speed, the outside temperature, the type of brake pads and rims, and more.

The sure thing is: if one has to stay for so long on the brakes during a descent, then it's probably a journey that is best to avoid unless prepared to let the bike safely go. Staying for miles with the brakes on, doesn't do good even with normal clinchers.

Just how can anyone make tape last? I have yet to find a removal, when using tape, where half didn't stay on the tub and half on the rim, hence making road side replacements a pain. Glue however stays there and assuming the spare is an old one with some residue left will go straight on. Ideally it may be re glued at home . As for gaps. With tape , no idea but with glue I always was told as a nipper to leave an inch or so opposite the valve to help removal as other wise the tub was there for ever. Good gluing of course.
As an aside I was given a very light but elderly tub the other day. Like most decent ones it won't hold air for weeks. But about 40ml of tubeless tyres sealant has solved that. Its kept 100psi for nearly a month.