Indoor trainer tyre question

[Henley 1]

I have a Wahoo Kickr Snap – the one with the bike’s tyre running on a steel wheel. Software Zwift. Besides plenty other Zwift-related irritations, I sometimes find that my power output varies substantial from one day to another, yet heart rate and perceived effort is the same (and route is also the same). Watt readings can vary + and – 20% for no reason known to me. Yes, I check the tyre pressure, and try to keep the wheel to IDT slip resistance constant. Yes, I do a “spin down” every few rides …. What else should I do to achieve more constant power output?

 

[Dubber]

No other suggestions I'm afraid.  Temperature may play a role, but I doubt to the extent you describe.

 

Wahoo do recommend a Spin Down before every ride.  But, that said, I don't think it would make such a big difference.  But I could be wrong.

 

There are a couple other troubleshooting tips you could use to get to the bottom of things:

 

1:  Try another app and see if you get the same issues (if not, issue lies with Zwift).

2:  If you have the means, switch protocols i.e. from ANT+ to Bluetooth etc.  If you can't change protocols, try getting your laptop/pc as physically close to the trainer as possible.  Even put it on the floor next to the trainer for a ride - just to see if things improve...  If it does, maybe you have some interference.

3:  If you have a friend with a power meter, invite them around.  Compare output numbers from trainer to power meter.  Alternatively, take trainer to bike shop and ask them to test...

 

I know there are specific tension settings required - I'm assuming you have followed the setup process correctly

 

Edit:  link to setup process just in case:  https://support.wahoofitness.com/hc/en-us/articles/115000382224-How-When-do-I-Perform-a-Spindown-Calibration-on-the-KICKR-SNAP-

Edited October 2, 2020 by Dubber

[SwissVan]

I have a Wahoo Kickr Snap – the one with the bike’s tyre running on a steel wheel. Software Zwift. Besides plenty other Zwift-related irritations, I sometimes find that my power output varies substantial from one day to another, yet heart rate and perceived effort is the same (and route is also the same). Watt readings can vary + and – 20% for no reason known to me. Yes, I check the tyre pressure, and try to keep the wheel to IDT slip resistance constant. Yes, I do a “spin down” every few rides …. What else should I do to achieve more constant power output?

Sorry I can’t offer a solution, but for troubleshooting purposes I would suggest trying another online platform instead of Zwift, this would eliminate one possible cause.

If the same thing happens on another app then you know the problem is at home....

Either your IDT is faulty or the transmission of the data from the IDT to the app is intermittent.

 

Rouvy free trail link

https://rouvy.com/en/pricing

[Shazybug]

I have a Wahoo Kickr Snap – the one with the bike’s tyre running on a steel wheel. Software Zwift. Besides plenty other Zwift-related irritations, I sometimes find that my power output varies substantial from one day to another, yet heart rate and perceived effort is the same (and route is also the same). Watt readings can vary + and – 20% for no reason known to me. Yes, I check the tyre pressure, and try to keep the wheel to IDT slip resistance constant. Yes, I do a “spin down” every few rides …. What else should I do to achieve more constant power output?

I used a Tacx Satori "semi-smart" wheel on trainer from Feb this year. This worked quite well, with consistent power output Decided to upgrade to a Snap last week. Saw the same issues you reported. Despite checking everything, and recalibrating, I saw no improvement in the power stability.

 

Does not help you, but I returned it the next day and "reluctantly" dug deep into my pockets for a Core. Has been superb so far.

[Henley 1]

Thanx guys for informative response. Just another thought that crossed my mind: maybe the surface area (read “smooth” for worn Gator Skin) of a tyre plays a role too? Difficult to set the pressure between tyre and IDT without letting slip happen and not damaging the bearings. Powering hard in granny gear requires quire a tight setting …. ? thanx again   

[Harryn]

It shouldn’t. I use old tires on my trainer bike, on my snap, until they literally start falling apart, and have not experienced the issues you describe. I do check tire pressure before every ride and do a zwift spindown before every ride to try and keep things constant. Power variance seems to be within the 5% range claimed by Wahoo.

[RobertWhitehead]

If you find the variance only on one metric (power) and not the other two (cadence and speed) then the problem is not likely to be with the connection. Like suggested by some of the others: try another platform like: Sufferfest, Rouvy, Fulgaz etc to see if this resolves the issue

[Vetplant]

I ride the old Computrainer(The grandaddy to all the wheel-on smart trainers)

 

My protocol is always:

-Check tyre pressure is correct(ie. 7bar, or whatever you prefer)

-Begin with no contact between wheel and trainer, spin up wheel.

-Turn knob on resistance wheel until contact is made, then turn another 5 quarter turns.

-Ride 10mins at fairly decent warm-up rate.

-Do Spin-down.

 

Only then, continue onto training workout or race.

 

With this approach the readings from Zwift and the Computrainer match up almost identical to what my Power Meter registers on my Garmin.

 

(The Garmin and powermeter is the combination I use for all critical metrics that go to Fitness Apps. Zwift and Computrainer just drive the workout. I know I can actually feed the PowerMeter readings to Zwift during the workout but it feels jaggy compared to leaving the Computrainer to do all the work itself. )

 

Don't know if this will help, but pretty sure the guys from Wahoo SA/Ikhambi will be happy to jump in and assist where they can. Have heard great things about their aftersales support.

[Henley 1]

Thanx all! this is what one would expect from this forum! take care on the roads