Ryan's Disc Bike #4 (Litespeed T1sl)

[RyanH]

Accuracy vs precision...

Accuracy of a power meter is less important as it can be corrected via slope adjustment. The day to day precision of the instrument though cannot be corrected for. These are just sample size of two but I'm getting meaningfully different numbers from yesterday to today:

First climb, average of 9.8%:



10.4% climb:



Longer segment of the above where it levels out a little near the top:



I'll get another ride in tomorrow and see if it drifts further. I did zero prior to riding. Today was 66* vs 69* for yesterday, so no big temperature diff.

Edited: first and second image were mixed up

[OtterSpace]

Thanks for sharing and I'm interested to see more as you have more data.

From what little research I've done the general online consensus of the Chinese power meters is that Xcadey is worse than Sigeyi. However, if you look through comments on GPlama videos some people complain about their Sigeyi power meter too.

The huge advantage of both of these Chinese power meters, over an SRM/Quarq/Power2Max is weight as the cost of a Sigeyi is close to a good quarq if you shop around.

[raisinberry777]

Certainly from what I've read most XCadey issues have been with their older Shimano crank arm power meters - the spiders seem to have been, for the most part, much more resilient.

Of course, the bigger issue is that if anything goes wrong, XCadey just seems to give people the silent treatment (or at least that's what I see looking on other forums).

[RyanH]

I've had multiple of the new Dzero and they've all been inconsistent. I did watch the GPllama review prior to purchasing this and he didn't point out any glaring issues. I'll see over the next few days how it fares. Rain in the forecast this weekend so I can see if that throws it off too. If it's not reading consistently, I'll order a Sigeyi to test next and then if all else fails, back to my good ol PM7.

[RyanH]

Forgot to include a photo of the bike with the new cranks, sitting at a little below 6.2kg:

[RyanH]

The Extralite wheels started creaking incessantly again. I thought my SiSL2 was having an issue which prompted the Elilee purchase but I spent an afternoon swapping parts only for the creak to continue until I swapped wheels.

Turns out the Extralite don't like rain much:





Fortunately I had some spare 61903 and 61803



I was reading another thread that Extralite does something with the bearings and them becoming toast quick is a common occurrence. Seems odd to me but the Enduro bearings in there have light blue seals which are different than the usual black seals I see. The other strange thing was that the inner freehub bearing and the inner body bearing was toast. Best guess is probably that the oring seal wasn't sufficiently greased and trapped water between the freehub and body.

[raisinberry777]

I've had multiple of the new Dzero and they've all been inconsistent. I did watch the GPllama review prior to purchasing this and he didn't point out any glaring issues. I'll see over the next few days how it fares. Rain in the forecast this weekend so I can see if that throws it off too. If it's not reading consistently, I'll order a Sigeyi to test next and then if all else fails, back to my good ol PM7.

That really sucks - though I'm thankful that you've tested because I've been looking at buying one.

Hopefully Sigeyi works out a bit better. Shame that Magene don't make a P505 for the Easton cranksets.

[RDY]

Accuracy vs precision...

Accuracy of a power meter is less important as it can be corrected via slope adjustment. The day to day precision of the instrument though cannot be corrected for. These are just sample size of two but I'm getting meaningfully different numbers from yesterday to today:

First climb, average of 9.8%:



10.4% climb:



Longer segment of the above where it levels out a little near the top:



I'll get another ride in tomorrow and see if it drifts further. I did zero prior to riding. Today was 66* vs 69* for yesterday, so no big temperature diff.

Edited: first and second image were mixed up

I don't think you can gather much meaningful insight on PM performance re: strava segments on different days. The numbers don't look anomalous. If you want to see how it's doing you'd need to compare it to a trainer or some PM pedals outdoors.

Both Dzero and Sigeyi have been fine for me, though the now ancient Dzero design isn't as quick to respond, and under-reads more than the Sigeyi (2-2.5% vs ~1%) relative to an Elite Diretto XR-T. Friend has a couple of the latest (wave design cover) Xcadeys and they're inseparable from Assiomas. I'll be using one on my new gravel build too.

[Ferry]

Fortunately I had some spare 61903 and 61803

I like that picture with the dog's paw, love dogs!
On topic, I am quite please with the PM7.

[RyanH]

I don't think you can gather much meaningful insight on PM performance re: strava segments on different days. The numbers don't look anomalous. If you want to see how it's doing you'd need to compare it to a trainer or some PM pedals outdoors.

Both Dzero and Sigeyi have been fine for me, though the now ancient Dzero design isn't as quick to respond, and under-reads more than the Sigeyi (2-2.5% vs ~1%) relative to an Elite Diretto XR-T. Friend has a couple of the latest (wave design cover) Xcadeys and they're inseparable from Assiomas. I'll be using one on my new gravel build too.

Yes and no. I've spent a lot of time on this subject and spent a lot of time and energy to make sure my PMs report accurately. On the flats, you cannot compare efforts because Rho (air density) becomes a factor as does wind. On a 10% or greater climb, particularly the one I use which is also relatively sheltered by the wind, things get tighter and more comparable. I plotted 200 data points for that segment over the weekend and tagged the PM used. My various SRMs had an absolute value average deviation between 1.5% and 2.5% when comparing average power by time (2-8 data points) with an average 1.75% variation and a max of 8.24%. Not taking absolute values, it's -0.94% variation.

Today, I took out the English with my Hollowgram SRM and did the same climb twice at 348 and 351 watts and the results were 1.1% and 1.1% different (higher) than prior data points for the same times (two different times).

If this were an SRM, I'd be able to calibrate it against my certified weight and then go from there. I tried calibrating this morning but it doesn't expose slope so I'm unsure how one would go about doing that. The other issue with lower grade PMs (and Shimano PM) is how they report cross chained and under different conditions. Anyway, my best guess right now is that it's reporting about 8% high, which I adjusted today and will test again, hopefully tomorrow.

With all of this said, I think the major discrepancy that I identified from the 28th to the 29th was the PM "settling" in. The 29th and the 30th were more consistent but I am concerned that the PM is more "off" at higher wattage (as a %) than at lower wattage.

[dudemanppl]

I went over to see this bike and Ryan told me to stop fingering his crankset

[gurk700]

I went over to see this bike and Ryan told me to stop fingering his crankset

“Oh, a rare dudemanppl post, lemme go check…”

“ofcourse”

[RyanH]

Took the bike to drop off and pick up the car across town. My wife thinks I need to replace the Litespeed decals since it's too much lol.

[spdntrxi]

just get the same color as the car