Power meter and Sub Compact Chainrings

Triathlon Forum
1

I’m building up a gravel bike and have decided on a 2x system with 46/30 front chain rings. The BB is BB86 if that makes a difference.

There are only a few manufacturers producing 46/30 rings right now and fewer that make a compatible PM.

Right now I think my options are in no order:

  1. Absolute Black 110/4 oval rings in 46/30 on a Stages Shimano Ultegra Crank. I’ve never ridden oval rings and these rings have a funky chain line to fit these sized rings on a 110 BCD crank.
  2. Easton EC90SL Cinch with their 46/30 direct mount rings and axle based power meter. I’ve read mixed reviews on the power meter, but there isn’t that much out there on them.
  3. Easton EC90SL and 46/30 rings with a Stages left crank arm.
  4. FSA SL-K Adventure crank with 46/30 rings and Stages left crank arm.
  5. Ride without power.

So essentially a couple different versions of Stages and Easton are my PM options.

Anyone have an option that I am missing or solution I hadn’t thought of?

2

Powertap hub?

I assume you want MTB pedals so the pedal based solutions would be out. But the IQ Square solution may be something sometime next year. They haven’t shipped the kickstarter orders yet.

3

Could you use a Mountain bike Power Meter or would that be too wide?

4

I was thinking a mountain would be too wide and the chain line would be funky.

5

I found some absolute black chainrings in a 46/30 but they are oval

https://absoluteblack.cc/oval-road-chainrings-30-46-and-32-48-for-110-4bcd/
.

6

I think they can be paired with a Quarq DFour Powermeter.

https://www.clevertraining.com/quarq-dfour-powermeter-spider-8-bolt-110-bcd

Someone needs to check over, might have to mill off the extra material on large chainring to fit the DFour. The inner looks like it will work.

7

I found some absolute black chainrings in a 46/30 but they are oval

https://absoluteblack.cc/…-32-48-for-110-4bcd/

That was the option #1 in the original post. If they were round, it would be problem solved.

8

I should learn to read better. At least this kept the thread at the top :stuck_out_tongue:

9

Thinking about a new frame build up also from my steel tank for racing next year. Currently running an FSA Energy 46/30 with Stages left crank on my Kona Rove. Ample clearance for the stages on this frame.

  1. Power readings can be higher with oval per Stages: https://support.stagescycling.com/en/support/solutions/articles/1000158537-can-i-use-the-stages-power-meter-with-oval-or-osymetric-chain-rings-

  2. Currently running this and works great. However the Stages pod won’t clear the frame I am looking at. If not an issue, I can recommend.

  3. Same issue as 4.

  4. This looks like my best option, and with Easton also being left leg only in the spindle, power should correlate well to my other bikes with Stages left only.

  5. Oh the horror :slight_smile: Did it for 15 years, and now with a year on power, it’s like I forgot everything.

  6. Wait until Spring and cross fingers that something new comes along.

10

Maybe post this question on the wattage group, they may be able to help.

11

If you can, hold off a couple of months. There are products to fit this niche coming down the pike.

12

If you can, hold off a couple of months. There are products to fit this niche coming down the pike.

Thanks for the tip… I’ll be patient.

13

I was thinking a mountain would be too wide and the chain line would be funky.

The chainlink would indeed be funky. I would not advise this route.

14

I might have found another option.

Rotor made a 46/30 Spidering that is compatible with their 3D+, 3D30 and Flow cranksets. I presume it will be compatible with the same power meters. Some places have stock, most are out of stock. I don’t see a current offering that uses the newer crank/spider interface. If some here knows better, I’d appreciate any clarification.

I’d prefer to have a both leg power meter so I think that limits it to the 2INPower. I’m not real familiar with that PM. The Rotor website sucks a bit and finding specific info on the compatibly of this 2017 model Spidering and the 2017 Power Meters is a chore. I contacted their customer service department in hopes to clarify.

15

Have you thought about whether you could get the same effective gearing with a standard 50/34 crankset and a custom cassette?

16

I’ve done the gear inch calculations for a 48/34 with all sorts of different cassettes that are readily available. My other requirement is Shimano shifter/brakes, so there are some workable solutions.

With 48/34 rings and a Shimano XT 11-40 cassette paired with a Ultegra RX GS derailleur on a Wolftooth hanger extender gives a slightly larger range as a 11-34 paired with 46/30.

Here’s a link to that comparison- and also my new favorite tool for gear inch calculations.

I’m not adverse to that solution, just exploring my options.