It’s both surprising, and not, if you think about it. The way I’ve usually seen it happen is first the rear tire goes flat, then the front one. My theory is that both tires went through the same pile of glass/thorns/metal bits and they both picked up junk. the reason for the flat occurring on the back first is because there’s more weight on that tire, so the offending article works its way through the tread more quickly.
Based on what we found, we chose the most relevant items and used them all. To test patches, I repaired holes using four different types of patches, from Novara (REI’s now-discontinued house brand), Park Tool, and Rema. Patching a tube isn’t hard but there are a few tricks, and the key was attention to detail and patience. I was extremely diligent in following proper patch procedure, which includes a thorough sanding of the entire area to be patched (for max stickiness) and properly letting the vulcanizer dry on both surfaces before applying. For the peel-and-stick patches, I went so far as to prep the area with canned air to ensure as tight a seal as we could possibly muster.
For the budding mechanic:  A good pocket sized repair guide.   One good option is the “Pocket Guide to Emergency Bicycle Repair”  by Ron Cordes and Eric Grove.   It’s only 3.5×4.5 inches and a half inch thick.   I don’t carry this myself, but for someone who’s new to this whole bike repair business, it’s really helpful to have. A future blog post will cover this book in detail.
There are patches that don’t require vulcanizer—the infamous peel-and-stick. One brand, the Park Tool GP-2, has some genuinely enthusiastic endorsements, so we tested it. I applied Park Tool patches to four different tires, at three different psi levels (60, 90, and 120). Three of the four didn’t hold—two released within minutes. The fourth deflated overnight. I redid the test, but repeated a second time, they all leaked within a day.
Unlike floor pumps, most hand pumps do not have pressure gauges. To get readings during my original round of testing for this guide, I built a special rig involving simple hardware-store parts. But the experts I spoke to seem divided on the usefulness of gauges. Half thought they were unnecessary, added bulk, and drove up cost. Why do you need a gauge if you know 100 pumps inflates your tire? But the other half liked them, because the “thumb test” is notoriously inaccurate.
I got some problems with my gears and I was wondering how to fix it, then got the idea on the internet about KELLY'S,I decided to go with them to fix the errors, that was my first time and was a great experience,they are all very accurate with their profession,very friendly,very polite and very honest as well,they just took half an hour to make me free.so,with the first experience I have become the fan of Kyle's.definitely suggested to everyone.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.
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