Kickr V5 power accuracy issue

naavt

Hi all,

I’ve bought a Kickr V5 which was already replaced twice, waiting now for the 3rd replacement! (I must say that Wahoo is being awesome here and always ready to solve my issue).

Why it was replaced for the 3rd time? Power accuracy issues.

I’ve begin to notice that my Sufferfest workouts were more difficult to finish after my swap from the initial Kickr Core to the Kickr V5, and decided to mount my powered meter bike on it, just to compare.

Results? An exponential difference in wattage where more watts resulted in a bigger difference, from my Quark power meter to my Kickr. As an example, intervals made at 100 / 200 / 400 on Sufferfest were registered in my Quark as 110 / 225 / 460 watts.

To make sure that it wasn’t my bike reading to high, I’ve tried a bike with a Power2Max power meter which came to the same results.

So for what it seems, I’ve had the same exact power accuracy issue on 2 different Kickrs.

Have any V5 owners experimented similar issues?

Wahoo told me that they’ve found a bug in their power module and that the team was working in a new FW release, which I think was already released a few days back. I’m still waiting for a 3rd Kickr and really hope this issue to be solved.

One other question: Doing some cadence drills where I pedal with one foot only, the Kickr reads half the cadence but my bike cadence sensor reads it right.

Is this also a normal behaviour on the Kickr?

Best!

whyamihere

I can't comment on the power accuracy, I'm also on my 3rd Kickr but I've only had v4s, I may need to raise a support ticket because it seems to be having dropouts.

The cadence observation is to be expected. The Kickr's cadence measurement works by looking for pulses in the power, which correspond to the downstroke where you put out the most power. Normally, there will be 2 of these per crank revolution, one for each leg. When doing single leg drills, pulling the crank up probably isn't producing enough of a pulse for the trainer to recognise, so it's just calculating off the downstroke of that leg.

thistle_

If it's a firmware issue, can't Wahoo just send you a firmware update to fix it rather than replacing the whole trainer?

I have a Suito and I'm pretty that the power measurement from the trainer is lower than using a crank power meter but I haven't been able to check for certain yet. There would be a a slight difference due to any losses in the drivetrain, but I'd expect it to be very small.

naavt

@whyamihere Thanks for your observation on the cadence reading. If that's a design aspect I will probably switch to an external cadence sensor.

@thistle_(mbnw) I don't know. It would be better for everyone really but if they are replacing my trainer is because it's not a FW issue and that scares me.

It seems that I'm not the only one and I've found other owners with the same exact issue that already gave up and just dial the effort percentage in Suf, Trainer Road or other Apps, but I find unacceptable for an owner of a trainer like this to use such workaround.

I'm a Wahooligan really, and every Wahoo gear that I have I've bought it with the confidence of having a great support team behind it. For now they have been tireless and super friendly.

For now I'm just waiting for a new Kickr, which is a bummer since it's raining for days and I don't like to get out on these conditions to train, but I just hope the next one to be flawless.

N0bodyOfTheGoat

thistle_(mbnw) said:

If it's a firmware issue, can't Wahoo just send you a firmware update to fix it rather than replacing the whole trainer?

I have a Suito and I'm pretty that the power measurement from the trainer is lower than using a crank power meter but I haven't been able to check for certain yet. There would be a a slight difference due to any losses in the drivetrain, but I'd expect it to be very small.

Reading power from the crank compared to at a direct drive turbo should supposedly be ~3% higher at the crank (more if drivetrain is all gunked up).

Zwift gave me an FTP estimate increase notification after doing a TT last night, but I think my Direto (used last night as using mobile Zwift app) over-reads by ~4% compared to my 4iiii (taking account of 3%), so I won't be changing my FTP estimate until I do a 4iiii effort.

naavt

N0bodyOfTheGoat said:

I have a Suito and I'm pretty that the power measurement from the trainer is lower than using a crank power meter but I haven't been able to check for certain yet. There would be a a slight difference due to any losses in the drivetrain, but I'd expect it to be very small.

Reading power from the crank compared to at a direct drive turbo should supposedly be ~3% higher at the crank (more if drivetrain is all gunked up).

Even if it were 3% higher it doesn't add up. I have more than 70w difference on an interval made around the 400w mark. That's a 18% difference!

N0bodyOfTheGoat said:

Zwift gave me an FTP estimate increase notification after doing a TT last night, but I think my Direto (used last night as using mobile Zwift app) over-reads by ~4% compared to my 4iiii (taking account of 3%), so I won't be changing my FTP estimate until I do a 4iiii effort.

On a single sided power meter you're prone to have a bigger difference if your left leg is the weaker one.

bobmcstuff

N0bodyOfTheGoat said:

thistle_(mbnw) said:

If it's a firmware issue, can't Wahoo just send you a firmware update to fix it rather than replacing the whole trainer?

I have a Suito and I'm pretty that the power measurement from the trainer is lower than using a crank power meter but I haven't been able to check for certain yet. There would be a a slight difference due to any losses in the drivetrain, but I'd expect it to be very small.

Reading power from the crank compared to at a direct drive turbo should supposedly be ~3% higher at the crank (more if drivetrain is all gunked up).

Zwift gave me an FTP estimate increase notification after doing a TT last night, but I think my Direto (used last night as using mobile Zwift app) over-reads by ~4% compared to my 4iiii (taking account of 3%), so I won't be changing my FTP estimate until I do a 4iiii effort.

I don't particularly rate the Zwift auto-detect function - they gave me 295, whereas my last actual test result is 283 (which neatly corresponds to my efforts on ~hour long races).

It's OK to give an indication but I wouldn't be setting workouts off of it - if I did all my workouts at 295 (a bit over 4% up) I would be failing them.

pblakeney

bobmcstuff said:

N0bodyOfTheGoat said:

thistle_(mbnw) said:

If it's a firmware issue, can't Wahoo just send you a firmware update to fix it rather than replacing the whole trainer?

I have a Suito and I'm pretty that the power measurement from the trainer is lower than using a crank power meter but I haven't been able to check for certain yet. There would be a a slight difference due to any losses in the drivetrain, but I'd expect it to be very small.

Reading power from the crank compared to at a direct drive turbo should supposedly be ~3% higher at the crank (more if drivetrain is all gunked up).

Zwift gave me an FTP estimate increase notification after doing a TT last night, but I think my Direto (used last night as using mobile Zwift app) over-reads by ~4% compared to my 4iiii (taking account of 3%), so I won't be changing my FTP estimate until I do a 4iiii effort.

I don't particularly rate the Zwift auto-detect function - they gave me 295, whereas my last actual test result is 283 (which neatly corresponds to my efforts on ~hour long races).

It's OK to give an indication but I wouldn't be setting workouts off of it - if I did all my workouts at 295 (a bit over 4% up) I would be failing them.

Agreed.
The figure Zwift gave me was more than I have ever managed to actually meet.

N0bodyOfTheGoat

bobmcstuff said:

N0bodyOfTheGoat said:

thistle_(mbnw) said:

If it's a firmware issue, can't Wahoo just send you a firmware update to fix it rather than replacing the whole trainer?

I have a Suito and I'm pretty that the power measurement from the trainer is lower than using a crank power meter but I haven't been able to check for certain yet. There would be a a slight difference due to any losses in the drivetrain, but I'd expect it to be very small.

Reading power from the crank compared to at a direct drive turbo should supposedly be ~3% higher at the crank (more if drivetrain is all gunked up).

Zwift gave me an FTP estimate increase notification after doing a TT last night, but I think my Direto (used last night as using mobile Zwift app) over-reads by ~4% compared to my 4iiii (taking account of 3%), so I won't be changing my FTP estimate until I do a 4iiii effort.

I don't particularly rate the Zwift auto-detect function - they gave me 295, whereas my last actual test result is 283 (which neatly corresponds to my efforts on ~hour long races).

It's OK to give an indication but I wouldn't be setting workouts off of it - if I did all my workouts at 295 (a bit over 4% up) I would be failing them.

The new figure Zwift gave me the other night matched up with 95% of my best 20mins according to Elevate For Strava plugin (formerly known as Stravistix) and www.crickles.org gave me.
Usually this figure works for training zones in ERG workouts, albeit I usually struggle with the sprint intervals, but rare 60min all out efforts are always lower than 95% of 20mins.

bobmcstuff

N0bodyOfTheGoat said:

bobmcstuff said:

N0bodyOfTheGoat said:

thistle_(mbnw) said:

If it's a firmware issue, can't Wahoo just send you a firmware update to fix it rather than replacing the whole trainer?

I have a Suito and I'm pretty that the power measurement from the trainer is lower than using a crank power meter but I haven't been able to check for certain yet. There would be a a slight difference due to any losses in the drivetrain, but I'd expect it to be very small.

Reading power from the crank compared to at a direct drive turbo should supposedly be ~3% higher at the crank (more if drivetrain is all gunked up).

Zwift gave me an FTP estimate increase notification after doing a TT last night, but I think my Direto (used last night as using mobile Zwift app) over-reads by ~4% compared to my 4iiii (taking account of 3%), so I won't be changing my FTP estimate until I do a 4iiii effort.

I don't particularly rate the Zwift auto-detect function - they gave me 295, whereas my last actual test result is 283 (which neatly corresponds to my efforts on ~hour long races).

It's OK to give an indication but I wouldn't be setting workouts off of it - if I did all my workouts at 295 (a bit over 4% up) I would be failing them.

The new figure Zwift gave me the other night matched up with 95% of my best 20mins according to Elevate For Strava plugin (formerly known as Stravistix) and www.crickles.org gave me.
Usually this figure works for training zones in ERG workouts, albeit I usually struggle with the sprint intervals, but rare 60min all out efforts are always lower than 95% of 20mins.

I thought it was just doing 95% of your best 20 mins, but two things:

1) My Zwift given one (295) doesn't match ZwiftPower's calculation, even though both were set in the same race (ZRL Everything Bagel race) and supposedly use the same basis (ZP gives me 95% of 303 watts = 288 watts FTP), so I am not really sure what Zwift is up to. Could be something to do with zero values in the race maybe (see below).

2) I am not sure that taking it from an unstructured ride is totally valid.
If I look at that best 20 mins from that race, it is not a steady effort. The power is all over the place, I was descending in supertuck for parts of it:


(graph from TrainerRoad)

That doesn't look like a good FTP test profile, does it... Leaving aside that I set massive power PBs in that race which I haven't been able to repeat (something about nearly getting dropped 4 or 5 times...).

I prefer intervals.icu to Stravistix btw, although similar in concept.

kevin4AqoFaYD

Naavt - (first time posting here!) I've had a very similar experience. I've owned Kickr's for ~ 3 years. Have had 2 Kickr 18s that I used for some time that ultimately had to be returned for HW/noise issues. Received the new Kickr V5 under warranty a few weeks back and have set up. FWIW - the 2 Kickr 18s were essentially identical in power readings before they crapped out due to noise issue.

The power / wattage benchmarks are way different from the past 2 trainers (which matched nearly identically) The difference is about 15%. In other words, 250 watts on the 18s feels WAY easier than the 20. Like two totally different products. Similar percentage drops as you describe.

I have contacted support and they've been responsive. Asking me to pair to the Wahoo app vs TrainerRoad, make sure all other pairable devices are powered off, check for firmware update etc. Going to give all this a go but it is sure demoralizing thinking that my numbers from the last 3 years could be artificially inflated vs reality...we'll see.

How was your issue resolved? Really interested in if there was an issue and a fix potentially. thx
KTB

redvision

kevin4AqoFaYD said:

Naavt - (first time posting here!) I've had a very similar experience. I've owned Kickr's for ~ 3 years. Have had 2 Kickr 18s that I used for some time that ultimately had to be returned for HW/noise issues. Received the new Kickr V5 under warranty a few weeks back and have set up. FWIW - the 2 Kickr 18s were essentially identical in power readings before they crapped out due to noise issue.

The power / wattage benchmarks are way different from the past 2 trainers (which matched nearly identically) The difference is about 15%. In other words, 250 watts on the 18s feels WAY easier than the 20. Like two totally different products. Similar percentage drops as you describe.

I have contacted support and they've been responsive. Asking me to pair to the Wahoo app vs TrainerRoad, make sure all other pairable devices are powered off, check for firmware update etc. Going to give all this a go but it is sure demoralizing thinking that my numbers from the last 3 years could be artificially inflated vs reality...we'll see.

How was your issue resolved? Really interested in if there was an issue and a fix potentially. thx
KTB

Sounds like a faulty unit as the v5 had a fix issued recently and according to Dcrainmaker it has addressed all accuracy issues.

naavt

@kevin4AqoFaYD

Yes, @redvision is right!

It took 3 Kickrs to solve this but it's done (thanks to all Wahoo staff involved on solving my issue! You were super friendly and unwearying!).

Only yesterday I had the time to test my 3rd unit and I was very happy to see that all numbers added up!

I've done a short interval training (Sufferfest Cash Register), which has some solid Tempo efforts mixed with some sprints, the ideal scenario to test the Kickr's ERG and power responses.

I've forgotten to disable Power smoothing on Sufferfest's App and that's why that power curve is smoothed out, but you can see that both power curves (Kickr and my Power2Max NG), tracked beautifully.

Hope this helps you on finding a solution for your issue!

kevin4AqoFaYD

What ultimately was wrong with your Kickr v5? Did they ship you a new one that matched with prior Kickr Core numbers?

They told me to update my firmware via Wahoo App which I will try. They also said there is a possibility of slight differences in watts between the 18 <> 20 v5. I cant see how it can be in the range of 30-40 watts though. My plight to solve this continues....frustrating.

naavt

This was my 3rd Kickr V5. Wahoo swapped my Kickr 2 times.

This last one is spot on with both my Power2Max and Quarq bikes.

My previous 2 Kickrs were off by more than 40w at the higher end of my wattage.

Sprints At 900w had a difference of almost 80w plus