Anybody have any experience with a wired cannondale SRM install on an SL4 SWorks Tarmac? I'm thinking about picking one up and was curious as to whether there was anything special I needed spindle-wise for the install.

I'm currently running a wireless Hollowgram SRM on my SL4, and you'll need the special SRM spindle, which is a tad longer to compensate for the SRM spider.

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"black on black, is a crime"

You may need extra room on the drive side to fit the SRM electronics. There is a two stage solution to this problem. The SRM specific spindle moves the setup ~1mm to the right and the SRM specific dust shield moves the setup another ~1mm to the right. You can use either or both, depending on your frame's clearance needs.

If you already have a "normal" spindle and need just 1mm of space, get the dust shield as it's only $15. If you don't have a spindle yet, get the SRM version as buying the normal spindle and then discovering you need more room would be expensive.