Upgrading Crankset and Getting a Power Meter...Thoughts?

Hey Everyone,

I’m looking for some general thoughts/recommendations on upcoming upgrades to my 2018 Trek Emonda with Mechanical Ultegra R8000 and BB90 setup. The general options being considered (feel free to make alternative suggestions) are as follows:

  • I’m on the shorter side (172cm height) so the 172.5mm crankset is slightly long for me and, ideally, I’d switch to 167.5mm, but haven’t ruled out 165mm if the cost savings is too great to pass up.
  • Option 1 - Upgrade the crankset and get a pedal-based power meter system. Under this scenario, I’d go with either a 165mm Ultegra or 167.5 Dura-Ace crankset and would target the Favero Assioma Duo-Shi. Biggest question on this option (assuming I can source it) is the cost-benefit of 167.5 Dura-Ace.
  • Option 2 - Upgrade to a spider or crank based power meter. If I go the route of Stages, 4iiii, and a few others the primary limitation is no 167.5mm option and, of course, accuracy since these have had issues - Shimano format in particular. If I go the Quarq route, I get the 167.5mm option and a product known for its accuracy, but the limitations are the approximated left/right balance GXP conversion which may present some friction and/or wear issues.
  • General Notes - Rotor doesn’t appear to play nice with BB90 and SRM is twice the cost of the most expensive option above so that just can’t be justified.

Does anyone have any strong opinions/feelings on the above options? Also, feel free to propose some other recommendations or share what you’ve done. Thanks for the help and remember, it’s always fun to help others spend money on cycling!

A Power2Max NGEco with Rotor Aldhu 24 (24mm spindle) works with a BB90 bottom bracket. That’s my setup with a 2018 Emonda. It’s been a great PM. You can keep your Ultegra chainrings that way.

I’d be careful with 4iiii/Stages crank pod-based PMs as the chainstay clearance is tight.

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Personally I went the 162.5mm quarq route and have been happier with it than the other PMs I’ve tried (PT hubs, PT C1, stages, & garmin vector’s). That said I rode maybe 200 miles on my friend’s bike with Assioma’s and they seemed to work fine; I like my pedals though.

Before selling my 2015 Domane I was looking at Quarq DFour GXP and Power2Max NCEco. No real issues with my Stages gen3 Ultegra 8000 on the Domane, but GPLama got into my head about crank arm power meters on Shimano’s hollowtech arms.

I strongly recommend biting the bullet cost wise and getting something pedal based. They are essentially future proof for all your bikes, and will be 100% compatible (especially the garmins where you can change pedal bodies between road and SPD). It’s expensive, but it saves money in the long run (I’ve had to buy 3 PM’s in 3 years due to compatibility issues, before i settled on the Garmin pedals)

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What @Northshorerider wrote. And that’s coming from a Quarq user since the Cinqo.

@seamusmulliganferry Thanks for the recommendation on Power2Max. It’s an intriguing option. Probably the biggest question going that route is the elimination of the 167.5mm option. Also, great points on the 4iiii/Stages cranks having some clearance issues.

@Alaric83 Quarq is interesting to me and I’m glad you had a good experience. Out of curiosity, do you have a BB90 or some other standard? As for the Assioma’s, they now have the Duo-Shi option as well so that’s up for consideration so long as I’m comfortable sacrificing the 167.5mm crank for the 165mm setup. It’s hard to justify spending the extra money on Dura-Ace just to get 167.5mm cranks.

@WindWarrior I’ve heard from some that the GXP setup doesn’t always play nicely with BB90. I’m guessing you went a different route (pedals?) since @GPLama got in your head. What are you using now?

@Northshorerider Future proofing the investment so that you only have to buy an extra pair of pedals for an older bike is a great idea. While comparing the Garmin Rally 200’s to the Favero Assioma Duo-Shi’s, it’s hard to justify the extra $450-$500. Do you find a lot of value in the Garmin pedal dynamics or was the choice more of a, “ehh, that’s the available option”? As for cranks, regardless of a pedal-based system, I am looking at shorter options. Any thoughts on the 165mm Ultegra vs 167.5mm Dura-Ace?

@Landis I appreciate the recommendation from someone using a Quarq power meter. Any thoughts on the Assioma vs Garmin systems? Also, if I am looking at changing the crank length, any thoughts while we’re at it on the Ultegra 165mm vs Dura-Ace 167.5mm cost-benefit?

Most quarqs you can interchange the spider onto different axles so its just about as future proof as the others. I use a quarq GXP that has been interchanged onto BB30, PF30, BB86, BSA, etc without issue.

It’s a 2014 Cervelo S3, the BB is BBright I believe.

I sold the Domane and bought a Tarmac SL7 with SRAM Rival groupset (Dub). Put a SRAM Red/Quarq crankset on it, that I bought during Black Friday sales. Never found a use for the Stages “true left-right” power reporting, and have been very happy with total power on the Quarq.

@redlude97 Thanks for the insight. I suppose it’s in the interest of Quarq and any other company to make them adaptable. The tradeoff like comes in the ease of switching between pedals and cranksets.

Thanks for sharing the BB details. I’m curious if anyone’s had issues with conversion kits.

@WindWarrior That’s really helpful to know. Instead of worrying about the conversion you just bought the BB standard for the power meter…nice! While the ability to track left-right power separately is interesting, I’m not sure if anyone has made any major training strides from knowing that they’re 55/45 vs 51/49. Looking at it from another perspective, you might hear someone at TR tell you to instead focus on single-leg exercises and build towards equivalence that way.

With the Stages most of my rides were 49/51 or 50/50 or 51/49, with a few like 52/48 and what not. I simply don’t care with total power or left-right power. And I had outgrown the Domane, and wanted something with a more aggressive geometry. Also wanted electronic shifting and a year ago the only reasonably priced bikes had SRAM Rival or Force. So now I have Dub spindle and I think its a BSA threaded bottom bracket, although I never had problems with the Domane’s press fit.

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I’m 176cm and run 165mm cranks FWIW, I strongly doubt you’d tell much difference (either perceptively or in true performance/comfort) with a 2.5mm difference, so go the cost effective route I’d say. Also consider how easy (hard) 167.5mm cranks will be to replace/copy in the future…

As for the PM, nobody has mentioned the one glaring downside of the Assioma-Shi, which is the horrendously wide Q factor. Whilst some are not sensitive to it, some definitely are! And if you’re on the smaller side width-wise as well as height-wise, you really don’t need that extra wide stance. I personally run Dura-ace pedals for this reason, as they’re ever so slightly narrower than most pedals.

I use the Garmin xc100s because I only mtb and gravel. Currently very happy with them, but I use all garmkn products and love how seamlessly they work together. I’m perfectly happy with single sided as well, but I’ve never used dual sided so maybe ignorance is bliss?