# Rpm’s fluctuating **URL:** \ **Category:** Bugs and Support\ **Created:** [July 1, 2024, 8:19pm UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889 "2024-07-01T20:19:27Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![D\_R7](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/d_r7/32/531476_2.png) [@D\_R7](https://forums.zwift.com/u/D_R7)\ **Post date:** [July 1, 2024, 8:19pm UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/1 "2024-07-01T20:19:28Z")
My rpm’s are rising and falling while my cadence remains steady. Just started doing this when I changed bicycles on trainer. Use a Tacx Neo smart trainer. I’ve tried unplugging all components and restarting. ---
**Author:** ![chris\_andrews\_TO](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/chris_andrews_to/32/465274_2.png) [@chris\_andrews\_TO](https://forums.zwift.com/u/chris_andrews_TO)\ **Post date:** [July 1, 2024, 11:59pm UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/2 "2024-07-01T23:59:02Z")
I use the same trainer and rpm does vary a bit even if I try to hold a steady cadence. How much is the variance? ---
**Author:** ![Paul\_Southworth](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/paul_southworth/32/538336_2.png) [@Paul\_Southworth](https://forums.zwift.com/u/Paul_Southworth)\ **Post date:** [July 2, 2024, 12:15am UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/3 "2024-07-02T00:15:04Z")
Does this happen if you test it with the Tacx app? If so talk to Garmin. Also if this is a Tacx trainer that has a built in cadence sensor, it’s possible the sensor is not detecting the crank arm. That would be consistent with your comment about switching bikes. Garmin may provide you with a metal plate to strap onto the crank arm, or you can find some random piece of steel to do that yourself. > **[How Do the NEO 2/2T and NEO Bike Series Trainers Measure Cadence? | Garmin...](https://support.garmin.com/en-US/?faq=btBijKpQyY6MQ11TybJVE9)** > > Garmin Support Center is where you will find answers to frequently asked questions and resources to help with all of your Garmin products. ---
**Author:** ![D\_R7](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/d_r7/32/531476_2.png) [@D\_R7](https://forums.zwift.com/u/D_R7)\ **Post date:** [July 2, 2024, 11:12am UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/4 "2024-07-02T11:12:57Z")
Drastic, I’ll be spinning at 80 rpm and it drops to 25. Even the avitar slows to a walking pace. I also had mounted a MTB on trainer so I selected MTB off the Zwift menu. Do u think that messed things up? ---
**Author:** ![D\_R7](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/d_r7/32/531476_2.png) [@D\_R7](https://forums.zwift.com/u/D_R7)\ **Post date:** [July 2, 2024, 11:17am UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/5 "2024-07-02T11:17:28Z")
Good question! I’ll read info u posted and see what is going on. Thanks! ---
**Author:** ![Paul\_Southworth](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/paul_southworth/32/538336_2.png) [@Paul\_Southworth](https://forums.zwift.com/u/Paul_Southworth)\ **Post date:** [July 2, 2024, 12:43pm UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/6 "2024-07-02T12:43:03Z")
Selecting the MTB in game will not affect those readings. It just reduces your in-game speed unless you are riding on dirt or gravel. ---
**Author:** ![Daren](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/daren/32/5836_2.png) [@Daren](https://forums.zwift.com/u/Daren)\ **Post date:** [July 2, 2024, 1:02pm UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/7 "2024-07-02T13:02:09Z")
> [@D\_R7](#): > > Use a Tacx Neo smart trainer. The Neo 2 at least is known to be a bit flaky if your crank isn’t big enough to trigger the sensor. I have a piece of metal as an extension to my crank to make sure something passes over the cadence sensor. ![image](https://global.discourse-cdn.com/gozwift/original/4X/c/e/b/ceb2229f51d76d7dba154241d67d9d164f76b5c1.jpeg) Might be the same on the Neo, and could have changed if you’ve got smaller cranks on the new bike for example. ---
**Author:** ![chris\_andrews\_TO](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/chris_andrews_to/32/465274_2.png) [@chris\_andrews\_TO](https://forums.zwift.com/u/chris_andrews_TO)\ **Post date:** [July 2, 2024, 1:10pm UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/8 "2024-07-02T13:10:20Z")
yes, that is far too much and isn’t normal. It must be connected to the change in bikes so try what Daren is suggesting. ---
**Author:** ![D\_R7](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/d_r7/32/531476_2.png) [@D\_R7](https://forums.zwift.com/u/D_R7)\ **Post date:** [July 2, 2024, 7:40pm UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/9 "2024-07-02T19:40:35Z")
I unplugged everything and rebooted app and it seems to be okay. I only did an 8 minute test ride, I’ll know more on Thursday when I have a training ride scheduled. I only Zwift 1 or 2 times a week because it’s been so perfect outside. Thanks all for helping !! ---
**Author:** ![D\_R7](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/d_r7/32/531476_2.png) [@D\_R7](https://forums.zwift.com/u/D_R7)\ **Post date:** [July 8, 2024, 3:49pm UTC](https://forums.zwift.com/t/rpm-s-fluctuating/631889/10 "2024-07-08T15:49:01Z")
U were right. My MTB had 2 inch longer chain stays. I put metal rod extension off crank and back to normal. Thanks Daren