Differences Rotor crank and Rotor SRM crank - swapping arms

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Timmetje
Posts: 11
Joined: Wed Nov 12, 2014 2:01 pm

by Timmetje

I am considering buying a (used) SRM with rotor crank arms. My position is dailed in but I am thinking about trying some different crank lengths this season. Therefore, does anyone know if the crank arms used on the rotor 3D SRM are any different from the ordinary rotor 3D arms?

If they are identical it would allow me to change the crank for a different length (as described in other threads). It would be similar to for example a power2max where the powermeter is simply the spider part of the crank. However, the dura-ace SRM crank arms are different from the ordinary dura-ace arms, and are thus not easily swapped. Of course the swapping procedure is similar but it would mean crank arms are only being sold via SRM, which makes it very costly.

I suppose the SRM rotor crank arms have several extra holes drilled in them to bolt them to the SRM spider, but I need to know for sure. Can I buy an ordinary rotor 3d crank and use this for an SRM?

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Pokerface07
Posts: 213
Joined: Wed Jun 06, 2012 11:43 pm

by Pokerface07

Just saw this post. I'm sure you found the answer already - but for anyone else - the Rotor crank arms used for the 3D SRM are specially machined for the SRM unit. So no, you can't just swap in standard ones. (The NDS arm is standard).

If you have a 3D+ version though, I believe it's a straight swap of arms from a standard road crankset.
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Tillquist
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Joined: Fri Dec 30, 2005 3:33 pm
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by Tillquist

Image

Here is a SRM Rotor 3D, it is NOT standart mount from Rotor


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Geoff
Posts: 5395
Joined: Sat Dec 13, 2003 2:25 am
Location: Canada

by Geoff

As a related aside, I am running a Rotor SRM on Danny Martin's bike from last season and it is a really good unit! It is impressively stiff and light. I would recommend that system to anyone.

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