12 April 2011

how to mount and glue a tubular tire

Tubular tires are the best. It's my blog so I get to say stuff like that. The weight savings alone over a clincher rim and tire combination are significant (at least 100 g) but you also get increased resistance to pinch flats, the ability to run lower tire pressure for increased traction (not just a concern for cyclocross!) and increased suppleness/comfort because of the taller tire profile.

Plus, no matter how far clincher technology advances, tubulars are PRO. As is most every niche/trendy/complicated/steeped-in-tradition thing in cycling.

That said there are drawbacks. Gluing a tire is not a quick process even if you are efficient and ideally you need 48 hours before you want to actually ride your tubular. And if you get a flat the process of removing the tire, cutting the casing threads, patching the tube, sewing the casing back up, gluing the base tape back on and re-gluing the tire is too much work for most people; usually they just buy a new tire.

In my experience if you train on clinchers and save your tubulars for races you can get two solid years out of a set of tires assuming you don't get a flat. Minimum. This is a good thing because quality tubular tires cost a lot. Even with a midweek race or two all summer long I have used the same tires for three(!) full seasons.

There are loads of techniques and variations if you will be using tubular tires for cyclocross, etc. but this post will primarily focus on road tires for use on road bikes.

Supplies
You will need the following.

  • Floor pump.
  • Two tubes of glue per tire.
  • Some Latex, etc. gloves or a plastic bag or a small, disposable acid brush for spreading the glue around. If you opt for a brush, be sure to buy several!
  • A truing stand is really nice but not essential if you have your bicycle in a work stand.
  • Very fine sand paper.
  • Glue solvent or acetone and some not very linty rags.
  • Box knife and/or putty knife.

New Tire/New Rim
This is the most common scenario and also the easiest. Here is what I do.

  • Mount the new tire on your wheel and pump it up to about 140 psi. Then let is sit for a couple of days. This will 1) stretch the tire and 2) make sure you did not get a lemon.
  • Remove the tire from the wheel and inflate it just enough so that the tire starts to turn inside-out and the base tape is facing up when you lay it on the ground.
  • Apply a thin layer of glue on the base tape of the tire and using a brush/glove/plastic bag spread it around so the entire base tape is covered edge-to-edge in a thin layer.
  • Set the tire aside to dry for 2-24 hours. Much longer is not recommended but one whole day is totally fine and can make the job of mounting the tire easier.
  • Put your wheel in the truing stand and lightly sand the tire bed. All you are trying to do here is rough it up just a tad so that the glue will have a better purchase.
  • Apply a layer of glue to the tire bed. Be sure that coverage is edge-to-edge here as well but do not get too much glue in the spoke holes or the valve hole. Better to apply with caution and then apply more as needed than to spluge the whole tube into your rim. It will never come out if you do.
  • Now is the time to clean up any glue that accidentally got onto your braking surface! If your braking surface has glue on it you will get a violent and unwelcome surprise the first time you apply the brakes. Set the wheel aside to dry for 2-24 hours.
  • Before you mount the tire, install your valve extender! It helps to use a tiny bit of plumbers tape/thread tape so air does not leak out when you pump up your tire. If your valve extender does not let you open or close the valve, open it all the way and don't worry about it. You will never lose any air by riding even at highway speeds down a mountain pass.
  • Put the wheel back in the truing stand and apply a second layer of glue to the tire bed. Again, be sure you get edge-to-edge coverage and don't get too much in any of the rim holes.
  • When you mount the tire start with the valve. Insert the valve all the way and then put the wheel on the ground with the valve at the top of the wheel. Grab the tire on both sides of the valve and pull it down HARD as you slowly mount the tire working your way around the wheel all the way to the bottom. The last bit will be hard but if the first layers of glue are dry enough and you have applied just the right amount in your second layer you should not get any (or much anyway) glue oozing out from under the tire as you pop the last bit on the rim.
  • Pump about 20-30 PSI in the tire and put the wheel back in the truing stand and spin it. If you see that the tire is not centered on the rim, grab it with both hands and lift it up and move it over and place it back down. You will probably not be able to simply slide it sideways.
  • Add a little air and repeat this process until it looks as centered as possible. Let the air out if needed to center it and then put a little back in.
  • Pump the tire up to 120 PSI and let it dry for 24 hours before riding it.

New Tire/Old Rim or Old Tire/New Rim or Old Tire/Old Rim
Once you own some tubular wheels and get a flat this becomes the most common scenario.

  • Deflate your tire all the way in case it still has some air in it.
  • Start opposite the valve and try to pry the tire off the rim from one side.
  • Do this on the opposite side of the tire as well.
  • Repeat the process working from both sides of the tire until you can 'tear' the tire off of the rim. In many cases you will need to use a screwdriver to help pry the tire off especially if you have done a good job of gluing it on in the first place. :) Just be careful so you don't damage your carbon rims! If you are just going to mount a new tire you don't need to care if you damage the tire.
  • Remove any big chunks of glue from the rim. This is where the box knife or scraper come in handy. Again, be careful not to damage the rim and always err on the side of leaving glue on the rim rather than trying to get it all off – you are only trying to remove the big, dry, blobs, NOT ALL THE GLUE. This is also a good time to clean up the braking surface if you have any glue there and even the edge of the tire bed. Having glue where there is no tire does not help. In my experience fine sandpaper is preferable to solvents which can make a big mess if you are not careful.
  • If the tire is new, inflate it so it turns inside-out and coat the base tape with a layer of glue.
  • If the rim is new, put it in a truing stand and apply one layer of glue to the tire bed.
  • Let your tire and/or rim dry for 2-24 hours.
  • Even if your rim has lots of glue on it, apply another layer being careful to get edge-to-edge coverage and not to force glue in any of the holes.
  • Mount the tire per the above instructions.

And that's pretty much it. Some people are WAY more meticulous than this insisting that you get all the glue off the rim each and every time you glue on a tire but in my experience this is absolutely not necessary. They are probably only saying that because of liability concerns and their legal team required it.

In my experience new glue will activate old glue and as long as there is good coverage and you have those three layers of glue and there is no dirt or old chunks of dry glue then you are good to go.

Here are some guides and videos from people that are much more meticulous than I am.

Park Tool
http://www.parktool.com/blog/repair-help/tubular-tire-gluing

VeloNews
http://velonews.competitor.com/2010/08/bikes-and-tech/technical-faq/video-how-to-glue-a-tubular-tire_132537

Zipp

Mounting and Gluing Tubular Tires

No comments: