Friday, March 01, 2013

Get the most out of your rear shifting.

I was on a ride a few years ago with a woman who was in town form Charlotte, NC and after the ride she made the comment that she hadn't shifted her bike that much in a long time. CLT must be flatter than central PA. None the less it got me thinking about cyclists, their riding habitats and how equipment selection can reflect that.

Shifting can't be totally dismissed on the bike unless you're choosing the ways of the Jedi via single speed drivetrain and that's a whole other story. The rear derailleur experiences more use than the front derailleur and sometimes become the bane of every cyclist's existence depending on their riding conditions and maintenance techniques.

During my last bike build for a local cyclist, he requested use of white cable housing on the bike. The housing was cut for him at a local shop which he received in a large loop. This allows custom cut lengths by the mechanic, in this case, me. When it came to running the rear shifter cable, the stock cut housing from Shimano, by my preference is too short.



A short rear derailleur housing length will shift fine for the first 1k miles but after that, things need adjusting due to 'cable stretch'. i.e., friction and internal wear at the derailleur housing loop. You need to cut the rear derailleur housing to length of 36mm. (Also use alloy housing ferrules on the ends of the housing instead of plastic ones which will crush after time thus affecting cable tension.) 36mm will provide a large enough loop to keep the cable pulling smoothly versus the stock housing length. During the lifespan of the rear shifter housing, too small of a radius in the housing loop will create more drag at the cable.


 From another blog, I explained that I'm a big advocate for using Campagnolo Ergo cable kits with my SRAM Red kit. The stock Campy cable for the rear derailleur will not allow you to use a 36mm loop nor the stock cut housing for said derailleur. In this case, I'll sub the stock Campy rear shifter cable for an Delta Duracote Teflon shifter cable and use a section of Shimano SP41 grease injected shifter housing. Easy operation.

Shift away.
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