Old 07-14-13, 04:21 PM
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7->8 spd...should I be concerned about the chainline?

Hi all,

This is somewhat related to my previous post (http://www.bikeforums.net/showthread...=#post15828314).

I've decided to take my '99 Specialized HR from 7 spd. to 8 spd. (wish I had considered this *before* I bought a new 7 spd freehub and cassettes late last year...very poor planning Setting aside the fact I know I'll have to re-dish the rear wheel (good news is rear dropout is 135 mm and a 5 mm spacer that sits on the axle opposite side from the freehub can be removed or maybe replaced with a 1.5 mm spacer to make room for the new 8-spd freehub and cassette), I was curious if I need to be aware of any issues that might be related to how critical the chainline setup would be relative to the cassette. Here's why I ask....

Based on chainline specs from Specialized, cassette dimension data from the Sheldon Brown site and my best ruler/eyeball process |^( it looks like the rear chainline sits pretty much on center (give or take) with the 4th cog/gear of the 7 spd cassette. When I install the 8-spd freehub, (again using Sheldon Browns data) it looks like the chainline would then line up almost 1/2 way between the 4th and 5th gear/cogs (~.1 mm closer to 5). So, it still looks like the chainline sits in the center of the cassette.

Intuitively, it would seem that this is a nice, ideal arrangement and that, other than getting the dishing right/straight and aligned, it should be a no-brainer process. If there is anything anyone thinks I should know about or be aware of in this, please speak now or I am off to potentially screw up my bike when the freehub arrives next week

Thanks in advance...Steph
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