John C. Kirk (johnckirk) wrote,
John C. Kirk

Rim tape

# Sometimes when a bike tyre goes flat on you,
# Just look at the rim tape, to gather a clue

(Sung to the tune of "Mix Tape" from Avenue Q)

I recently got a flat tyre on the Brompton's rear wheel. These are always a nuisance to fix, but fortunately they don't happen very often. My most recent repair involved an extra step, so I've now improved my understanding of how the bike fits together.

I took the wheel off the bike, then took the tyre off the wheel. I then noticed a worn patch on the "bottom" half of the inner tube:

Worn tube and exposed spokes

Those round lumps of metal are where the spokes join the rim, and the rim tape is supposed to cover them up, but it was in the wrong position. Here's a clearer view:

Clearer view of rim tape in wrong position

So, presumably the tube has been rubbing against the metal, without the tape to protect it. The actual puncture was elsewhere, but this didn't seem like a good situation, so I decided to replace the tape.

I got my first Brompton punctures in September 2009, and I commented that both wheels had blue plastic rim tape. I then took the bike into Evans so that they could replace the rear tyre (since I'd damaged the sidewall), so they must have replaced the blue plastic tape with this cloth tape at the same time.

I replaced the rear tyre again in April 2010, upgrading from Marathon to Marathon Plus. I assume that I must have looked at the new rim tape at that point, but I didn't notice anything odd about it. So, either Evans put it on correctly and it has since slid out of position, or they put it in the wrong place and I didn't pay enough attention to notice.

Either way, I wanted to get the rim tape into the correct position, and using new tape seemed easier than removing the existing tape and repositioning it. Digging around online forums, the general concensus is that the blue plastic tape that comes with Brompton wheels is rubbish and that Velox is a good brand. The tape should just go into the "well" (rather than going up the sides), so it needs to be the correct width: for a Brompton wheel, that's 10mm. I normally buy supplies like this from Evans, Wiggle, or Chain Reaction Cycles; they all sell rim tape, but none of them sell the correct width. For instance, the narrowest I could find at Evans was 16mm. So, that would explain why the existing rim tape was so wide, but I think they would benefit from stocking something narrower, if only for their workshop.

Instead, I went to Cycle Sports UK. I bought a frame pump for my Roberts bike there (after I had trouble finding it anywhere else), and they do fast/free delivery, so I'm happy with their service. They charge £1.99 for Velox rim tape, so I bought 2 rolls. Each roll is longer than I need, but only has a single valve hole, so you can't really share a roll between wheels. Still, that's not really a problem, since it's so cheap. Here's a comparison of the old and new tape:

Old and new rim tape

The old one was 18mm across, whereas the new one is 10mm across. I put the new tape onto the rim, which was very easy: I lined up the valve hole, then just kept unrolling the tape onto the rim, pushing it down as I went. When I'd gone all the way around the wheel, I cut the tape with a pair of scissors. (It's more like Elastoplast than Sellotape, so I think you'd struggle to tear it off.) Here's how it looked once it was in place:

New rim tape on wheel

I think that looks a lot neater than before, and hopefully it will do a better job of protecting my inner tube.

As for the repair work in general, I think I'm getting quicker with practice:
5 mins to take the wheel off the bike.
5 mins to take the tyre off the wheel (using Park Tool TL-1 tyre levers).
5 mins to replace the rim tape and inner tube (not including the time it took me to take photos).
30 mins to put the tyre back on the wheel (bare hands, no tyre levers).
8 mins to put the wheel back on the bike.

I've also started to keep a log of repair work, so that I can keep track of how long things last, e.g. how many km I can do on a tyre before the tread wears out.

Looking further ahead, I'm taking part in the Brompton World Championship next month. The video on their website is quite entertaining, with a Rocky-esque training montage. I don't expect to win, but it should be a fun day out. The race starts with all bikes folded up, so the quicker you can unfold yours the better: my best time so far is 12 seconds, and I'm practicing that on my daily commute.
Tags: cycling

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