Tuesday, February 09, 2010

Twaaaaang! #2

Well, more of a crack than a twang if I am honest. After this recent misadventure with a gear cable, on Friday I managed to do this to my rear derailleur gear cassette (click to biggify):

Yup, pretty sure its not supposed to look like that.......

This was incurred after I stopped and u-turned on my way to work to help a motorist with a flat tyre. I felt the bang as the cog was dismembered, but wrote it off as mere a mere chain crunch/slip. I suspected something might be awry when I couldn't keep it in top gear for the rest of the way to work, and confirmed that suspicion shortly after. Ironically, the previous day we had a free cycling maintenance workshop at work (as part of Bikewise month (link) ) where it was noted that my chain was worn and at risk of damaging a gear...

This weeks handy cycling hint: Don't get out of the saddle from a standing start and stand on the pedals with all of the power your mighty legs can put through the chain with your gears at extreme opposition. I had the gears set on the smallest and innermost front chain ring (low) and smallest and outermost rear cog (high). This puts the maximum sideways load on the rear cog, in this case enough to tear a piece of it clean off.

Funnily enough (now that I have belatedly looked it up), setting your gears like this is not recommended by the guru's :)

2 comments:

Andrew Mayfield said...

Bad luck with your bike. In the 90s your unrecommended position was called "cross chaining".

Off-Black said...

Yeah, I have always kind of instinctively known it was a bad thing to do, just didn't realise how potentially bad. It's only taken 20+ years of riding with a derailleur to find ou the hard way though! Oh well, lesson learned.