Tiagra to Ultegra crankset upgrade?
 

I'm planning to get a power meter and would like to upgrade to the Ultegra crankset. I have inquired with a few LBS and have gotten conflicting information where some shops say that it's incompatible with my bike's current setup: 10 spd Tiagra components with Praxis Works Alba crankset and others say it's doable.

Currently on a budget and was originally considering the Praxis Works Zayante crankset with 4iiii power meter. A friend suggested going with a Stages power meter with the Ultegra crankset.

If I go with the Praxis Works Zayante crankset, I'm able to reuse my current bottom bracket thus the cost may be lower. The Ultegra crankset will require more parts but appears to be more compatible with other Shimano parts.

Not sure which route to go... Any advice or insight would be greatly appreciated. Thanks!

Ultegra bottom brackets are $20 new. What are they saying isn't compatible?

I specifically inquired only about the crankset from Tiagra to Ultegra. The rear cassette and derailleur will remain the same.The following is the response I got from a "reputable" LBS. Yet other LBS tell me it's very doable.

"What you are attempting to do is not possible. 10 speed components are not compatible with 11 speed components.

It would be best to just stick with the cranks your bike come with. "

There's a miscommunication somewhere. If all you want to do is change the the crankset, then it's not a big deal. You can run a 10-speed chain on an "11-speed" crankset. (Cranksets really don't have "speeds")

On the other hand, if you're talking about changing shifters and cassettes to get 11-speed, then your LBS is correct. You'll need to change the shifters, RD, cassette for sure. Possibly FD and freehub too.

What is the cost of doing it your way with parts and labor?

Have to agree with caloso, must be a miscommunication. You are not changing from 10 to 11 speeds, just changing out the crank.

I'm trying to keep everything sub-$1k if possible including power meter. Going to bring it to the other LBS to get a quote.

I did a follow up on this matter, they said it's not possible because the spacing with the cranks are different. The different spacing supposedly would cause my shifters not to work properly...

Yup just the crankset, I even followed up and once again they said it wasn't possible. Something about the crankset spacing being off that would affect the shifters from properly functioning.

Why not scrap what you have. Avoid mismatched parts and get a whole new 105 groupset for $450 - $500 and the 105 power meter for another $300. $100 for labor?

I'm considering the 105 option as well. It might be more viable since it's an entire group set vs. specific parts.

Seems more logical in terms of performance, reliability and aesthetics. I really can’t think of a reason not to go in that direction.

I changed out a 10speed Tiagra crankset with an 11speed RS 500 (nonseries 105) crankset. Sill running all the other original 10speed components. No issues in a couple of thousand miles.

Keith

You will be fine running 10 speed on an 11 speed crankset. However I would take off the Tiagra and upgrade to 105 because matching is good and if you are interested in power meters then having a more reliable groupset in a more modern flavor is a good thing.

You should ask them what spacing would be off. Both cranks give the same chain line and the space between chainrings is the same for the 10 and 11sp cranks in seen.
I've used a 10sp crank with 11sp drivetrain and it works fine too(reverse of what you want).

That is simply an uninformed shop. There is no difference in chainring spacing between 10 and 11 speed double cranksets.

I agree. This makes no sense. I have run the same crank (Quarq) on 9, 10, and 11 speed set-ups. Worked fine on each.