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Friday, June 21, 2013

How to Screw Up a Flat Tire Repair

As much as I ride, you'd think I'd be able to handle flat tires quickly and efficiently. But, I got my first road flat of the year yesterday, and I did just about everything wrong. Here's some lessons learned...

DISCLAIMER: I am a lousy bike mechanic. But, I'm typically able to fix a flat in a reasonable amount of time. Yesterday, not so much. Here's the post-mortem on what happened, and things I can do in the future to prevent the same issues. Thought I'd share this, as it will happen to every bicyclist at some point. (Note: this article is for tubed tires only, if you're running tubeless tires, there's nothing here for you...)

The Debacle

So, I needed a short lunch-time ride that included some climbing work. So, I decided to ride up Shaw Mountain Road to Tablerock Road, and do as many hill repeats as I had time for (from the end of the housing on Tablerock Road to the end of the pavement). Here's the route I ended up riding...

Very near the end of my third repeat, I got a flat. No problem, I thought - I had a spare tube, a pump, and a patch kit. I got the tire off quickly enough, and thoroughly inspected the inside and outside of the tire for foreign objects. I had a piece of kevlar liner between my tire and the tube, and I realized that I didn't know how to remount that liner. I wouldn't say it was a problem, but it took me about 10-15 minutes to figure out how to get the liner re-inserted.

I re-mounted one side of the tire, inserted the tube, made sure the liner was seated reasonably well, and was feeling confident at that point. I had just purchased a new pocket-sized pump that I'd read some great reviews about. And that brings me to Problem #1: I hadn't practiced enough with the new pump at home, and I quickly broke the valve stem off of my spare tube trying to inflate it.

Okay, no problem - the valve stem on my spare tube and my punctured tube were both replaceable, so I popped the valve stem out of my punctured tube and screwed it onto my spare. Problem #2: My pump has to screw onto the valve stem to make a seal, and I did not have a pair of pliers with which to sufficiently tighten the replaceable valve stem. So, after pumping up the spare tube, the valve stem unscrewed itself with my pump and all the air gushed right back out of the tube.

No problem, I thought - I have a patch kit! I'll just fix the punctured tube. Problem #3: The glue in my patch kit was old and drying out - and would not spread properly or adhere to the tube and patch.

Fortunately, another biker happened along and graciously offered up his spare tube. I popped it in, pumped it up (with his frame pump) and I was set. Thanks Nicholas!

This could have been a real debacle. I may have had to walk 6 miles or so back to work in road cycling shoes, completely destroying my cleats, or I would have had to interrupt a co-worker to come pick me up, assuming any of my friends even had time to do that.

Pretty much anything that could go wrong, did go wrong - and after a bit of reflection, I realized there were some lessons to be learned here.

Lessons Learned

  • Make sure you're carrying a pump, a spare tube, and a patch kit. I think it's fine to carry a previously patched tube as a spare, but some would tell you to discard a patched tube as soon as you can. That seems wasteful to me, though. If you do carry a patched tube as a spare, make sure and check it periodically to ensure it still holds air. If it's patched properly, it should last a long time, at least one season.
  • Know your tire and tube setup, and how to work with it. Do you have tire liners? Know how to reinsert them. (See  the "tips" section below)
  • Practice using your pump in the safety of your home. Especially if you're using a small pocket pump, which can be tricky to operate. Don't wait until you're stuck on the side of the road to try and figure it out.
  • In general, if you get a flat, I think the best thing to do is to replace your tube - and then repair the punctured tube once you get home.
  • Check your tire repair kits at least yearly. Once you've cracked open a tube of glue, check it more frequently. If the glue is starting to dry, replace the patch kit. I've done a bit of research on whether or not you can just replace the rubber cement in the patch kit, since the cement always seems to run out or dry up before you use all the patches. My conclusion? It is cheaper to just replace the whole darned kit. Also, you really should use the "special" type of rubber cement that comes with a patch kit, rather than a generic off-the-shelf rubber cement. The cement in your patch kit will create a stronger chemical bond between the patch and the rubber tube than will standard rubber cements.
  • Make sure your multi-tool has a gadget that will tighten a replaceable presta valve, or carry a tiny set of pliers.


Lastly, Bicycling Magazine has a lot of nice articles with easy-to-follow tutorials on common repairs. Here are a couple that are applicable to fixing a flat...
  • How to Fix a Flat on the Road - I think this is a great, simple article on how to fix a flat road-side. One thing I would add - I like to seat one side of the tire before inserting the new tube. I just find it easier to do than inserting the tube first. They talk about running your fingers along the inside of the tire to find the foriegn object that caused the flat. This is IMPORTANT! If you don't do this, you may get another flat tire 5 minutes later. In fact, I like to completely remove the tire, pop it inside out and carefully inspect it. I also inspect the outside of the tire for foreign objects like goatheads or pieces of glass.
  • Patching a Tube - one thing I think they forgot to mention in this article, though - is that if the patch is going to be covering a "bead" on your tube, make sure and sand the bead flat before applying the cement, or you may end up creating an air channel underneath the patch
  • Flat Prevention, and How to Install (or Re-Install) Kevlar Liner Tape - Pretty good article from REI - skip to the "Tire Liner" section to learn how to deal with Kevlar tire liners when fixing a flat...reading that section alone would have saved me quite a bit of time yesterday...
  • If you want to go deep on this topic (and I mean DEEP!) check out this Sheldon Brown article. If you can make it through this article, you will know it all.
Hope this helps. I know this article is far from comprehensive, if there are any good tips, suggestions, rebuttals - please leave a comment!


  1. REx, I've totally had the same thing happen with a valve stem breaking off! Glad I'm not alone. Do you carry a C02 cartridge? I carry a pump as back up, but the cartridges are awesome!

  2. Hi Kathleen! I don't carry a Co2 cartridge, but I'd been considering it lately. They don't seem like they'd add much weight, and it would be nice to not have to fool around with a pump if you didn't have to...