Help getting Stages 105 Power Meter on Older Bike

I wound up buying a 2017 Salsa Warbird 105 (5800) this Spring. Conveniently Stages was clearancing out their Shimano 105 5800 LH Power Meters. Works great, no complaints.

However, I would like to get it on my road bike as well. I have a 2008 Cervelo RS with Dura-Ace. Unfortunately, Dura-Ace doesn’t extend to the cranks. Has a FSA front crank, and 10 speed cassette in back. Went to my FLBS yesterday, and the mechanic could not figure out a way to get new Shimano on it. The new 105 stuff is all set up for 11 speed, and he thinks there’s a good chance that getting the 105-7000 front crank and a bottom bracket wouldn’t work.

It would be so much better if I could ride both my gravel and road bikes with power, hoping someone has some clever way that I could make it work.


IIRC, all of the Shimano Hollowtech II crank parts are compatible with each other. So you could get, say, an Ultegra 6700 crank, which is 10-speed, and put a Stages 105 left arm on it.

I’m curious why he doesn’t think the 105-7000 crank and bottom bracket would work?

The nice thing about Shimano Hollowtech II is that you can mix and match left/right sides all day long (I have a 2018 4iiii left side powermeter crank mated to a 2005 Dura-Ace right side, zero problems).

And an 11 speed crank will work with a 10 speed chain.

So I can’t imagine why your LBS didn’t suggest a new bottom bracket and whatever Hollowtech II drive side fits your budget.

Sorry for the delay in response, work got crazy the last couple weeks.

I wasn’t totally clear: LBS mechanic knows the Stages 105 crank will work with a new Shimano front crank of whatever variety… he’s concerned that the front derailleur on my old Dura Ace might not be compatible with the new drive cranks, because the old Dura Ace is 10 speed, all of the new components would be 11 speed. He was confident there was some difference, and thought there was a 50/50 shot of getting it to work.

My wife would kill me if I bought new Dura Ace to convert everything to 11 speed (although I wonder if my rear wheel could handle 11 speed?). Would hate to downgrade, as even 10 year old Dura Ace is still better than brand new 105 (I think). But it’d sure be nice to have power on my road bike…

@jpowers: LBS can only get new parts, I suppose they’d probably install 2nd hand parts if I paid them… On this bike I’d prefer to go with new if possible, it’s my garage queen bike :star_struck:


Highly doubt that’s an 11 speed wheel so to convert to 11 speed would m an a lot of new parts.

As far as 10 year old Dura-ace vs new 105… the new stuff will be better… for sure.

I also can confirm that a new 11 speed crank will work just fine with a 10 speed chain, Rd FD, etc. I’ve been doing that for a while now.

I am running a 105 5800 11 speed crank with everything else being Ultegra 6700 10 speed. Everything works great.

Shimano’s new 105 groupset is definitely superior to your old DuraAce in every way, except for potentially weight. But IMHO you should not try and upgrade your groupset on such an old frame. Bottom bracket standards are a royal pain.

Instead, I’d look into getting a pedal-based power meter such as Garmin’s Vector 3 or Fabio Assiomas.