So with the ‘Finishing Touches’ series over and done with it’s time for the Tuesday Tune-Up to turn to the real hands-on stuff…
This week: Gluing tubular tyres.
Before I start, my apologies for the lack of images here – I don’t currently have any rims that need gluing so I’ve not been able to do this a step-by-step image guide. Hopefully it’s descriptive enough to be clear.
First things first, don’t go near any glue – get those tyres unpacked and mounted onto a set of rims. Doesn’t matter if they’re not built wheels yet, or even if they’re a spare set of clincher rims – all you’re doing is getting them pumped up to about 150psi to get them stretching for a couple of days.
One last thing before I crack on – myths aside, ageing a tub in a cellar, garage or anywhere else is not going to be of any use to man nor beast, and until anyone can give me concrete evidence that is serves any benefit beyond “but it’s what the pro wrenches do” then I’m not listening! Tyres are not good wines that need ageing to improve – they’re designed to be used! Besides which ageing rubber is only likely to harden it up and make it more brittle.
Now, where were we?…
On the question of how many layers to use, assuming everything is new I always put 2 coats on the tyre – the first generally just soaks into the base tape, and whilst that would probably hold I prefer the security of an extra layer. I try to allow at least 8hrs between applying layers. If you’re just putting a pre-glued tyre onto a previously glued rim then one coat on the rim should be sufficient.
When applying glue to the tyre, get some air into it (20 psi should do) then grab opposite sides of the tread in a ‘pincer’ grip so that the tyre forms a kind of figure-of-eight in your hand. This is easy to both apply the glue and manoeuvre the tyre around as you work.
With the rim the general consensus is that it needs scruffing up a bit before you glue. You can do this, but there’s evidence (yes, someone somewhere has lab tested this) to suggest it’s not necessary – you’ll be fine with just some acetone for a degrease (DO NOT use nail varnish remover, it’s not the same stuff). Make the first layer of glue reasonably thin. Leave to cure for 6-8hrs (or more, it doesn’t hurt) then apply another. 3 layers is probably enough, and I think I’ve even used 4 before, particularly if I was sparing (i.e. overly thin) on the first few layers.
DO NOT SCRIMP ON GLUE TO SAVE WEIGHT! Only an idiot would do such a thing – the weight saving is negligible, and you’ll regret it if you roll your tyre off on a corner and ruin your shiny light weight carbon rims in the process!
With 3 decent layers of glue on the rim and a decent coating on the tyres, I then apply a thin layer of glue to one of the rims only, then whack the tub straight on. There are numerous tips and tricks here (some leave that layer for 15mins or so, others use a spray of water before mounting to ease moving the tyre once it’s on), but ultimately it’s about what works for you, and how you can achieve the result you need.
For me, I have the tub at about 20psi because I find it holds its shape and I can still stretch it enough to get the tub on evenly – with 30 or 40psi which I’ve tried before I can’t apply enough stretch to effectively even out the tyre on the rim, and the last bit goes ‘thin’ as a consequence. As this translates to a bumpy ride I prefer to avoid it! Set the wheel on the ground, resting against your legs with the valve hole at the top. Stretch the tyre by pulling sideways as you put the valve into the hole, then set yourself so that you can force your weight down to stretch the tyre as it goes onto the rim. The last bit will be a pain (and obviously you can by then pick the wheel up to do it), but it shouldn’t be too bad if you’ve applied enough pressure at the top of the wheel. Be prepared to use almost your full weight stetching the tyre as you mount it. You can practice this with the unglued tyre and wheel before you start.
With the tub on the rim you can use the line of the base tape of the tube to ensure the tyre is even on either side of the rim – you kind of ‘lift and turn’ the tub to even it out, and this should be easy enough to do with the fresh layer of glue still being tacky. Once it’s fairly even looking on both sides you can then even out any side-to-side wobbles. Do this by either feeling the tyre and rim in your fingers as you run them around the rim (you can only understand how effective this is when you actually do it) or by sight when you spin the wheel. Again, you should be able to shuffle the tyre one way or the other to get it straight.
Finally, pump the tyre up nice and hard (again, around 150psi) then roll the wheel on a hard surface with all your weight on it to force the tyre into the rim. I’ve heard rolling the flat tyre along a broom handle on the ground also works here, and it’s easy to see how and why. Leave it around 12hrs, then reset the pressure to what you intend to run. Try to leave it a full 24hrs before using them in anger.
Ok, so it’s not all that easy the first time, but it does get better with practice! A few things that have made my life easier are:
- Using a tin of Conti glue with the brush in the lid (it’s just like painting)
- Good lighting so you can see where you’re applying the glue
- Keeping track of where the brush stopped last time you took it off the rim (use a spoke or a rim sticker as a reference point, but you can also often see where the glue is still wet)
- Having somewhere to hang the tyre or wheel once the glue has been applied (nothing worse than putting it down onto a fluffy carpet!)
- Having nothing around you that you want glue getting on, and turn off phones, email etc until you’re done
Things I have read that seem to have helped others so I’ll pass them on for you to try:
- Use an old toothbrush to spread the glue if you’re not using a tin with a brush in the lid
- Gloves seem like a good idea but often aren’t – especially thin mechanics ones that’ll often just tear and leave patches on the tyre and / or rim (you might get away with decent kitchen or garden gloves)
- Mask the rim wall with tape if you think you’re going to be messy (I’ve never needed to, and it could take as much effort to clean up the brake surface after tape removal as it might have been to clean up errant glue). Apparently electrical tape is much easier for this purpose!
- Use a wheel truing stand to apply the glue to the rim (also serves as a handy drying rack)
Other than that, make sure any valve extensions are 100% sorted and be sure to get the tyre orientation right BEFORE mounting!
Finally, enjoy it. Personally I don’t think there’s anything more cathartic in cycling than gluing tubs now and it makes me wonder why I took so long to get around to it. DO IT!
P.S. For anyone thinking “sod it, I’ll just use tub tape” – consider this: Tape is for wrapping presents, not mounting tyres. Please don’t, it’s nasty stuff.