Power2max S - drift when indoor training?

LeeDa

I've had a couple of the S Powermeters for about a year and in general they've been pretty good. However I seem to get quite a bit of drift in numbers when training indoors. Temperature of the room when starting is typically quite cold and small so temperature does change quite a bit as I go through any workouts. If after 20-30mins I stop pedalling and do the 5 sec calibration thing the power then rises sometimes by 10-20w - same gearing, same cadence. Also the issue isn't just a one time in a workout calibration thing - if I were to do at the 40min mark I would again see a change in the numbers. Both units seem to have the issue. I never notice the issue outside (obviously harder to notice in outside conditions but outside riding often freewheeling for the odd few seconds anyway so constantly calibrating).

I thought these had internal temperature correction that continuously corrected without the need to do the calibration. The only other thing I consider is it something to do with the lubrication of the roller drums (Kreitlers) that somehow changes resistance when you stop pedalling - though I'd find that just bizarre if was that.

Does anyone else experience this?

venster

Funnily enough, I had same issue a few days ago on the turbo.

I started off without the fan on in the garage but needed it after 20 mins or so but I had it blowing at my legs - and my P2M started reading really low...after stopping pedalling for 5 secs it was back to normal. Don't have the same issue outside either !

AK_jnr

Not sure if its the same with your turbo, but the resistance on mine goes up once its warmed up. I used to think it was just me tiring before I got a power meter!

twotyred

I have a 2011 P2M that does this. I sent it back to P2M to be upgraded when they introduced temperature compensation and that did help a bit but power readings can still rise 10W after about 10min use in a cold garage. Its not a huge deal as I know to auto calibrate after warming up and before I start any intervals. Even in the middle of a session I'll still autocalibrate to make sure. It's the only issue I've had with my P2M over 5 years use and the only thing that would stop me buying another so I'm disappointed to hear that the latest units might still have this problem. If I were you I'd get in touch with P2M and send copies of your power graphs to them and get them to accept the units back for repair.

LeeDa

twotyred wrote:

I have a 2011 P2M that does this. I sent it back to P2M to be upgraded when they introduced temperature compensation and that did help a bit but power readings can still rise 10W after about 10min use in a cold garage. Its not a huge deal as I know to auto calibrate after warming up and before I start any intervals. Even in the middle of a session I'll still autocalibrate to make sure. It's the only issue I've had with my P2M over 5 years use and the only thing that would stop me buying another so I'm disappointed to hear that the latest units might still have this problem. If I were you I'd get in touch with P2M and send copies of your power graphs to them and get them to accept the units back for repair.

Not a massive issue for me either, I too just do a quick calibration before an interval though it is more of an issue if doing a longer intervals. Certainly not big enough an issue to replace it but I probably would go for an alternative once it's time to replace.

twotyred

One place it is an issue is when going up an alpine climb where the ambient temperature can drop quite a bit and you don't want to/can't stop pedalling to autocalibrate. Its still possible to grab a few secs freewheeling at a hairpin but not ideal. These units are now used by pro teams who just would not put up with temp drift so I can't believe that the current units have this issue which is why I think you have faulty units.

janesy

ive had this issue once before. atleast noticable. 300watts became very easy. stopped peddling and it sorted.

meanredspider

I'd get in touch with P2M - if their customer service is half as good as Stages, you'd have had it fixed in less time than this thread has been running.

LeeDa

meanredspider wrote:

I'd get in touch with P2M - if their customer service is half as good as Stages, you'd have had it fixed in less time than this thread has been running.

I don't think it is so much a fault but just the temperature gadget thing isn't 100% effective. Actually lately mine don't seem so bad...I have removed the q rings but I wouldn't think that would not effect drift.

mankybianchi

Like other posters, I had my p2m under record an interval.

I had manually calibrated at the beginning and after the warmup. In the rests between the intervals, I stopped pedaling to let the PM do its auto-zero. The first two intervals were fine but starting the third one, I could see and definitely feel that something was not quite right. It seemed to be reading around 20 watts or so under for the same RPE. I stopped and calibrated through the Garmin which then returned the wattage reading and my effort to that of the previous intervals.

I contacted P2Ms service folk and they explained all was well. I was a bit disappointed when they then said that Power2Max was made for outdoors. Doesn't say that on their website or their literature, so I'm a bit grumpy about it.

Due to time constraints I do indoor training quite a lot which makes me think I've got the wrong thing.

janesy

It does say that the power meter does temperature compensation if you freewheel for 3 seconds. power reading goes to 0 it will auto calibrate.

I guess in that case its designed for outside... or you could just freewheel in doors a few times.

twotyred

The autocalibrate when freewheeling is separate from the temperature compensation. Temp compensation should be operating whilst you are pedalling.

amaferanga

MankyBianchi wrote:

I contacted P2Ms service folk and they explained all was well. I was a bit disappointed when they then said that Power2Max was made for outdoors. Doesn't say that on their website or their literature, so I'm a bit grumpy about it.

Due to time constraints I do indoor training quite a lot which makes me think I've got the wrong thing.

I don't understand why they would say it's for outdoor ONLY. Sure, the software algorithms may be designed to work best with normal riding outdoors, but it should work perfectly well indoors as well. Mine does anyway.

I suspect it works as well as most other power meters indoors. It could be worse - you could have bought a Stages....

Grill

Pretty normal. Just calibrate at the start of your ride and then at 20 minutes (also worth doing between intervals such as a 2x10 or 2x20).