Shimano Power Cranks (DA & Ultegra) - still FUBAR

[MichaelB]

If you hadn't heard, the Shimano PM's R8100 & R9200 (and I think prior) have unusually for Shimano, been woeful in terms of accuracy, but they have just released a software update to fix it.

Except it didn't ...

GPLama does a brilliant summary and analysis, as always ....



Yikes ....

[Dave_rh]

Anyone with Shimano 24mm axle crank sets, wanting reliable power, would be best considering alternate options.

For each option, you keep your existing bottom bracket and swap your existing chainrings onto the replacement spider.

- Rotor 24 modular axle/crankarms (Ahdhu24 or Vegast24 crankarms) with a power2max NgEco PM - This can be bought as a set from FESports AU.
- Magene PES P505 Base PM and axle/crank set - Not sure where this is bought from?

If the asthetics of a non-shimano crank bother you, Stages seem to have a reliable offering that uses the new shimano 12 speed crankset too...

[lone rider]

Anyone with Shimano 24mm axle crank sets, wanting reliable power, would be best considering alternate options.

For each option, you keep your existing bottom bracket and swap your existing chainrings onto the replacement spider.

- Rotor 24 modular axle/crankarms (Ahdhu24 or Vegast24 crankarms) with a power2max NgEco PM - This can be bought as a set from FESports AU.
- Magene PES P505 Base PM and axle/crank set - Not sure where this is bought from?

If the asthetics of a non-shimano crank bother you, Stages seem to have a reliable offering that uses the new shimano 12 speed crankset too...

I bought a Magene crankset from Panda Podium. Their prices are in $USD but it was around $450 AUD middle of the year when I bought it. They couldn't get one for nearly a month so it's was shipped Express for free. Even being Chinese based, their communication was always prompt and they were happy to refund if I didn't want to wait.

[g-boaf]

The one thing I liked about the DA9100 power meter cranks was the long battery life.

Anyhow, they’ve been replaced with brand new ones at Shimano’s cost.

[MichaelB]

[Dave_rh]

Shimano road (but NOT mtb) design seems unhealthily obsessed with having the spider and the crank arm as "one" piece... but actually comprised of 2 separate pieces glued together.

It's a credit to Shimano that they get even vaguely accurate power on the right side at all. With all the crazy shapes, different materials, big/vs little chainring forces, pedalling forces etc.

Maybe they want the marketing claim of measuring left vs right power, even if right side is wrong.

Quarq, power2max, rotor, etc worked this out long ago by using a separate direct mount spider PM. This eliminates all the interference and weird shapes and forces from sharing a spider with a crank leg.

[CmdrBiggles]

Quarq, power2max, rotor, etc worked this out long ago by using a separate direct mount spider PM. This eliminates all the interference and weird shapes and forces from sharing a spider with a crank leg.

The spider-integrated Quarq power meter (in SRAM groupsets from RED to Rival) can suffer from interference, although exceedingly rare in country/regional areas, but evident in frequency-saturated cityscapes. It is characterised by brief drop-outs or abnormally high or zero power. I have experienced this once; the anomaly was confirmed subsequently by SRAM in a recent email query raised with them.

[Dave_rh]

Quarq, power2max, rotor, etc worked this out long ago by using a separate direct mount spider PM. This eliminates all the interference and weird shapes and forces from sharing a spider with a crank leg.

The spider-integrated Quarq power meter (in SRAM groupsets from RED to Rival) can suffer from interference, although exceedingly rare in country/regional areas, but evident in frequency-saturated cityscapes. It is characterised by brief drop-outs or abnormally high or zero power. I have experienced this once; the anomaly was confirmed subsequently by SRAM in a recent email query raised with them.

Was not aware of that electrical interference issue . To clarify my earlier comment on interference. I meant specifically physical interference i.e. the shimano right crank leg and spider are a "single" and slightly asymmetric shape. Quarq uses direct mount which isolates the 2 different twisting forces of the crank from the spider and chainrings from each other.

If shimano used direct mount chainrings, it would mean the right leg power meter would behave and function just as normally as the left leg.

[g-boaf]

Never mind the accuracy, just mind that the cranks don't split apart and cause the unlucky rider to crash.

I have FC-09 cranks so I can criticise them.

[CmdrBiggles]

Never mind the accuracy, just mind that the cranks don't split apart and cause the unlucky rider to crash.

I have FC-09 cranks so I can criticise them.

He'll crash anyway, because he's transfixed by the facts and and figures on his Whoppee Wahoo, and did not see the lateral crack then pothole in the road that was his point of undoing...