SRM cranks

stulemanski said:

Quick question here to help me in my quest to some SRM cranks. I've seen some for sale, but they're square taper and I'm currently running shimano octalink. Soooo....

Is it possible to swap the square taper crankarms for shimano octalink crankarms?

As a real long shot, would it be possible to swap the crankarms to shimano 10-spd crankarms with an integrated BB axle?

I guess that it all depends on whether the crank-spider interface is the same for each of these models, but not having actually seen any that have been taken apart, I don't know whether it is theoretically or practically possible...

Cheers,
Stuart

If the cranks you're looking at are of fairly recent vintage but not the D/A 10 model, then the answer is yes, you can swap the crankarms to Shimano Octalink (and/or a different length if you like). The powermeter disk itself is attached to the crankarms via three Torx screws, so all you have to do is unscrew them, pop out the old arms (which will be very tight), pop in the new ones, and retorque to 15 Nm. New arms will cost you $170 from SRM.

Unlike the version immediately before them, but like even earlier SRM cranks, the powermeter used in the D/A 10 version cannot be separated from the crank arms.

SRM does sell individual crank arms so if you already have a left crank arm (Shimano or whatever), you can save some money buying just the right arm.

Some of the first Octalink SRMs had 5 Torx screws inside the powermeter spider securing it to the crankarm. Newer Octalink SRMs have 3 external Torx screws.

I'm not sure how the Dura Ace 10-spd SRMs are attached to the crank arms but I think the spiders and crank arms can be separated.

acoggan said:

If the cranks you're looking at are of fairly recent vintage but not the D/A 10 model, then the answer is yes, you can swap the crankarms to Shimano Octalink (and/or a different length if you like). The powermeter disk itself is attached to the crankarms via three Torx screws, so all you have to do is unscrew them, pop out the old arms (which will be very tight), pop in the new ones, and retorque to 15 Nm. New arms will cost you $170 from SRM.

Unlike the version immediately before them, but like even earlier SRM cranks, the powermeter used in the D/A 10 version cannot be separated from the crank arms.

stulemanski said:

Quick question here to help me in my quest to some SRM cranks. I've seen some for sale, but they're square taper and I'm currently running shimano octalink. Soooo....

Is it possible to swap the square taper crankarms for shimano octalink crankarms?

As a real long shot, would it be possible to swap the crankarms to shimano 10-spd crankarms with an integrated BB axle?

I guess that it all depends on whether the crank-spider interface is the same for each of these models, but not having actually seen any that have been taken apart, I don't know whether it is theoretically or practically possible...

Cheers,
Stuart

It seems to me that just buying a new ultegra/Dura-ace BB would be cheaper than buying the $170 arms.

just a thought

PSU

PSUcycling said:

It seems to me that just buying a new ultegra/Dura-ace BB would be cheaper than buying the $170 arms.

I was going to suggest that as well, but perhaps when stulemanski said that he's running Shimano Octalink he meant on multiple bikes.

In any case, you want a Campy or Campy-compatible b.b. to go with the SRM square taper crank arms. The Japanese standard for a square taper spindle is slightly different, which over the long run (and possibly over the short run, if you're always moving your SRM around) will speed the demise of the cranks.

acoggan said:

I was going to suggest that as well, but perhaps when stulemanski said that he's running Shimano Octalink he meant on multiple bikes.

In any case, you want a Campy or Campy-compatible b.b. to go with the SRM square taper crank arms. The Japanese standard for a square taper spindle is slightly different, which over the long run (and possibly over the short run, if you're always moving your SRM around) will speed the demise of the cranks.

this is true, the campy and shimano square taper are different, the angle of the taper is not the same. When you snug the aluminum crank onto the steel spindle, the aluminum gives slightly and makes a perfect fit, moving that style from spindle to spindle is a bad idea (each time the aluminum arm gets a little more pushed open and thus moving your crank more inboard) , and even worse if you put it on the wrong version.

Squint said:

Some of the first Octalink SRMs had 5 Torx screws inside the powermeter spider securing it to the crankarm.

I (obviously) did not know that - thanks for the info.

Squint said:

I'm not sure how the Dura Ace 10-spd SRMs are attached to the crank arms but I think the spiders and crank arms can be separated.

Well, it's an original Shimano crank arm that SRM has been cut up, so it obviously has to be attached somehow, which in turn means that there has to be a way of separating the pieces. OTOH, SRM doesn't seem to sell replacement D/A 10 crankarms, so it's a bit of a moot point.

Thanks to everyone for the helpful advice - I'm now much better informed to make the right decision as there are a couple of pairs advertised at the moment and it's a pretty expensive piece of kit (even 2ndhand) to buy the wrong thing!

Cheers,
Stuart