could you go pedal based? maybe a powertap rear hub. I would think 150mm crank arms based power meters are hard to find.

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2019 T-Rex Tri Series

I don't believe there are any crank based power meters with 150mm arms.

I have one successfully running Power2Max with Rotor 3D+ 150mm

I'm pretty sure Rotor 3D + Power2Max is your only option.

So far that seems like the only option, and honestly a very reasonably priced option.

As for the other questions, Pedal based is not out of the question, but she would rather not have to change pedal platforms. It would also not be cheap between the $1k+ pedals and $250+ non power crank. A powertap hub is also not out of the question, but she is happy with the tubeless carbon wheels that came with the bike and the are not PT compatible. When you price a PT hub laced to Flos (and the 150mm crank we are replacing anyway) it probably makes more sense to just go the pedal route.

That is kinda what I figured. Thanks for the confirmation.

This leaves the question of the Rotor 4130 bearings. Anyone have any experience running a 30mm spindle in a bb86 or bb90?

I guess I was wrong

You can't... And you don't have to. Rotor 3D has a 24mm spindle, it will fit right into your BB90 without any adapters. I have the same combination (Rotor 3D and P2M) on my speed concept.

I'll second what sp1ke above has said as I have a Rotor/Power2max that I swap between my Speed Concept (BB90) and my Shiv (BB30). Easy peasy.

Power2Max does not list the regular 3D in a 150 (or 155). In fact I can't find a place that has a non power 3D in 150 that I can buy. I could buy the Power2Max unit separately if I could find a rotor 3D in 150 somewhere.

Is the Rotor 3D24 the same as the old 3D? Did they redesign the crank or just change the naming convention? Will a power2max for a rotor 3D fit a 3D24 crank? So many questions.

It most certainly is possible to run a 30mm crank in a 41mm shell. The question is how well it works and how long the bearings will last. Hopefully someone on slowtwitch has some experience.

last time I checked, this store had 150mm rotor 3d+, you can give them a call.

https://www.twohubs.com/

The Power2Max site has the 3D+ type S in stock in 150mm. It's even on sale.

The question remains whether I can find a regular 3D with the 24mm spindle, which would be the ideal option.

I'd go with Powertap too.

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Developing aero, fit and other fun stuff at Red is Faster

I also suggest Power2max. Even if you needed a longer arm length I would still go that route. Highly reliable power meter. And the price is really good too.

I would NOT suggest P1 pedals. I cannot get a good working set from them. Several other riders in my groups have given up on their P1 pedals. Just not reliable.

You have gotten a little bit of bad info above. You CAN use the Rotor 3D+ (30mm spindle) in a BB86 frame. The specific bearings are 4130. They are a little smaller than what we consider normal bearings. I recommend these - http://wheelsmfg.com/products/bearings/sealed-bearings/bb86-to-30mm-sealed-bearing.html.

I'm pretty sure you cannot get the Rotor 3D+ (or any of their 30mm spindle cranks) into a BB90 frame as those frames are a touch wider than the 30mm Rotor spindles.

The 24mm version of the Rotor 3D (Rotor 3D24) allegedly has a 155mm option, but I have never seen one available any shorter than 165. The actual Rotor store website has them listed, but I couldn't tell if they are actually in stock.

The 30mm Rotor version of the Power2max will not fit on the 24mm Rotor cranks.

You always have the Watteam Powerbeat. It takes some manual work and you need to have hollow aluminum cranks, but DCRainmaker gives them a decent review. Also pretty decently priced.

They have a compatibility list on their site, most are shimano cranks.