Powermeter help - P2M 3d & Cervelo S5

Discuss light weight issues concerning road bikes & parts.
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TomH
Posts: 5
Joined: Thu Jan 07, 2016 5:21 pm

by TomH

Hi guys,

I currently own a Power2Max Type S mounted to Rotor 3D cranks and Praxis works rings. Having just purchased a used Cervelo S5, which came with a Rotor Inpower crankarm, I'm just trying to work out what the best option's are for me:

My winter bike is a Trek Domane with BB86, which I currently run the p2m on.
My Summer/race bike is the Cervelo S5, with a BBright bottom bracket for 30mm axle's.
I also work abroad most of the year and run a fleet of Trek/Boardman bikes, all of which have press fit BB's for 24mm Shimano axle's

Ultimately I'd like to sell the RotorInPower and use/purchase a true left/right PM such as my current Power2max. What would be the best option here... Change the bottom bracket in the Cervelo to a 24mm spindle converter? I've heard BBinfinite are quite good here, but can't justify spending over £100 on a BB, any slightly cheaper alternatives? This seems like the cheapest route as I'd just keep one powermeter and change between bikes. Any discernable difference between 30mm and 24mm axles?

Any one have experience with the RotorInpower? Any less accurate than P2M spiders? I love my praxis works rings for sublime shifting but q-ring compatibility has peaked my interested in this and may be something i look at in the future. Is it worth just keeping this?

Lots of questions, just trying to work it all out. Thanks for the help!

by Weenie


jones1991
Posts: 16
Joined: Mon Oct 15, 2018 2:17 pm

by jones1991

what about a hambini bottom bracket, think mine was around £90 ish but thats with high quality bearings and when they eventually wear out you just pull them out and press in new ones.. cheaper in the long run

kafreeman
Posts: 102
Joined: Thu Jul 23, 2015 8:46 pm

by kafreeman

A Rotor 3d + p2max would be a good option.

The inpower is single sided, it should be a direct swap for a rotor 3d crank if the axle is the same length. The inpower uses strain gauges in the axle, so it can only "see" one side.

Sent from my SM-G965U using Tapatalk



marioc
Posts: 32
Joined: Sat Mar 26, 2016 2:26 pm

by marioc

If you have bikes with BB86 and BBRight bottom brackets, I would suggest going with 24mm axle PM. I had 30mm axle PM on BB86 with Rotor 4130 BB and it didn't last one season without starting to creak. 24mm axle will go without issues on frames designed for 30mm axle with propper BB.
Same as jones1991 I switched to Hambini BB and 24mm axle Power2Max and it's been silent so far.

ryanw
Posts: 750
Joined: Sat Apr 16, 2016 6:52 pm
Location: London

by ryanw

marioc wrote:
Fri Mar 29, 2019 8:09 am
If you have bikes with BB86 and BBRight bottom brackets, I would suggest going with 24mm axle PM. I had 30mm axle PM on BB86 with Rotor 4130 BB and it didn't last one season without starting to creak. 24mm axle will go without issues on frames designed for 30mm axle with propper BB.
Same as jones1991 I switched to Hambini BB and 24mm axle Power2Max and it's been silent so far.
Sorry, but what absolute tripe.

BBRight BBs are designed for a PF30. They're 46mm ID shells, so you would use a Rotor 4630, which is just their name for a BB30 / PF30 (obviosuly you can use any PF30, CeramicSpeed, C-Bear, Kogel etc).

BB86 is a 41mm ID shell, so yes you would use a Rotor 4130 which has the smaller bearings (not as robust).

I have used BB30 PM's on my BBRight Cervelo's without a single issue.

marioc
Posts: 32
Joined: Sat Mar 26, 2016 2:26 pm

by marioc

ryanw wrote:
Fri Mar 29, 2019 9:57 am
Sorry, but what absolute tripe.

BBRight BBs are designed for a PF30. They're 46mm ID shells, so you would use a Rotor 4630, which is just their name for a BB30 / PF30 (obviosuly you can use any PF30, CeramicSpeed, C-Bear, Kogel etc).

BB86 is a 41mm ID shell, so yes you would use a Rotor 4130 which has the smaller bearings (not as robust).

I have used BB30 PM's on my BBRight Cervelo's without a single issue.
You missed my point. Cranksets with 24mm axle will go without issues into frames designed to accept 30mm axle (BBRight, PF30, PF30A, BB30, BB30A, BB386 Evo) with a proper bottom bracket bearing. BB86 is Shimano's standard designed around their 24mm axle cranksets. Crankset with 30mm axle in BB86 frame is doable with Rotor 4130 or FSA PF41-86.5-30 , but bearings won't last as long as bearings for 24mm axle.

ryanw
Posts: 750
Joined: Sat Apr 16, 2016 6:52 pm
Location: London

by ryanw

marioc wrote:
Fri Mar 29, 2019 8:09 am
If you have bikes with BB86 and BBRight bottom brackets, I would suggest going with 24mm axle PM. I had 30mm axle PM on BB86 with Rotor 4130 BB and it didn't last one season without starting to creak. 24mm axle will go without issues on frames designed for 30mm axle with propper BB.
Same as jones1991 I switched to Hambini BB and 24mm axle Power2Max and it's been silent so far.
I didn't miss your point. You gave out wrong, inaccurate information and I corrected you. :welcome:

hambini
Posts: 436
Joined: Tue Nov 15, 2016 8:13 am
Location: Bristol UK / Cologne, Germany

by hambini

To chime in here.

The problem is running a 30mm axle in a BB86 shell means you have to either grind down a 6806 bearing or use a 6706 bearing. Doing both of these results in a load carrying capacity diminishment of about 75%. You could take this as the BB will only last 25% of the time or you can only put through 25% of the max power.

Either way it is not a great idea.

I think MarioC is quite correct, if you are running BB86 and BBright, then a 24mm axle is preferable because it will work in both. If you have a 30mm crankset, the lengths can vary so some will not fit BBright because it is asymetrical and offset to the non drive side and they need to be a minimum of 90mm length for BB86 otherwise they will not fit. If you go for 24mm axle, they are all 90m+ so there is universal compatibility.

Hope that helps
Hambini

marioc
Posts: 32
Joined: Sat Mar 26, 2016 2:26 pm

by marioc

ryanw wrote:
Fri Mar 29, 2019 12:46 pm
I didn't miss your point. You gave out wrong, inaccurate information and I corrected you. :welcome:
Then I'm missing your correction. You stated BBRight and BB86 dimensions, so please, point out what did you correct?

ryanw
Posts: 750
Joined: Sat Apr 16, 2016 6:52 pm
Location: London

by ryanw

I disagree.

BBRight is a 79mm offset shell with 46mm ID. Multiple PM manufactures produce units to fit this, normally with an 88-90mm length spindle.

A 'true' BB30 is a 68mm shell w/ 46mm ID, but nowdays nearly all chainsets sold as BB30 actually refer to the 30mm spindle, not the true BB30 standard, and have longer spindles. With this in mind, 11mm washers are included with nearly all PM's these days to accommodate the longer spindle.

BB86 is a 86.5mm shell with a 41mm ID, where a 24mm spindle is recommended.

So for BBRight, a 30mm spindle is recommended, also being lighter and stronger than a 24mm.

ryanw
Posts: 750
Joined: Sat Apr 16, 2016 6:52 pm
Location: London

by ryanw

And then I take it all back since I see the thread is about Rotor 3D not their 3D+.

My bad!

User avatar
LouisN
Posts: 2605
Joined: Mon Feb 19, 2007 3:44 am
Location: Canada

by LouisN

I have a P2M for 3D ( NG Eco) for sale if interested ;) ...

Louis :)

1415chris
Posts: 1244
Joined: Sat Apr 18, 2009 8:59 am
Location: Surrey UK

by 1415chris

ryanw wrote:
Fri Mar 29, 2019 1:34 pm
And then I take it all back since I see the thread is about Rotor 3D not their 3D+.

My bad!
Rotor 3D is/was available with 24mm and 30mm spindle versions.

ryanw
Posts: 750
Joined: Sat Apr 16, 2016 6:52 pm
Location: London

by ryanw

1415chris wrote:
Fri Mar 29, 2019 4:36 pm
ryanw wrote:
Fri Mar 29, 2019 1:34 pm
And then I take it all back since I see the thread is about Rotor 3D not their 3D+.

My bad!
Rotor 3D is/was available with 24mm and 30mm spindle versions.
The Rotor 3D only came as a 24mm.

The 30mm variant was called the Rotor 3D30.

The Rotor 3D+ was their top of the range cranks, essentially a 3D30 with lighter arms etc.

TomH
Posts: 5
Joined: Thu Jan 07, 2016 5:21 pm

by TomH

hambini wrote:
Fri Mar 29, 2019 12:55 pm
To chime in here.

The problem is running a 30mm axle in a BB86 shell means you have to either grind down a 6806 bearing or use a 6706 bearing. Doing both of these results in a load carrying capacity diminishment of about 75%. You could take this as the BB will only last 25% of the time or you can only put through 25% of the max power.

Either way it is not a great idea.

I think MarioC is quite correct, if you are running BB86 and BBright, then a 24mm axle is preferable because it will work in both. If you have a 30mm crankset, the lengths can vary so some will not fit BBright because it is asymetrical and offset to the non drive side and they need to be a minimum of 90mm length for BB86 otherwise they will not fit. If you go for 24mm axle, they are all 90m+ so there is universal compatibility.

Hope that helps
Hambini
Thank you for the insights, I've decided to sell on my Inpower and purchase one of your bottom brackets, could you please recommned the correct one for my bike? 2016 Cervelo S5, currently has a Rotor 46/30 BB, and my power meter is a Power2max with Rotor 3D arms/axle (24mm) Am I correct in thinking I need the PF30 to Shimano classic bottom bracket?

Thanks, Tom.

by Weenie


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