# Physical or mechanical issue?

**URL:** <https://www.trainerroad.com/forum/t/physical-or-mechanical-issue/69723>\
**Category:** Equipment\
**Created:** [February 19, 2022, 4:49pm UTC](https://www.trainerroad.com/forum/t/physical-or-mechanical-issue/69723 "2022-02-19T16:49:34Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![getbent](https://sea2.discourse-cdn.com/trainerroad/forum/user_avatar/www.trainerroad.com/getbent/32/85073_2.png) [@getbent](https://www.trainerroad.com/forum/u/getbent)\
**Post date:** [February 19, 2022, 4:49pm UTC](https://www.trainerroad.com/forum/t/physical-or-mechanical-issue/69723/1 "2022-02-19T16:49:34Z")

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When I am riding on my trainer, and I am doing 100% ftp there is some clunky/grinding feeling in my drive train (pedaling) at lower cadence below 75 but when I spin above that it smooths out and no grinding type feeling/noise. This does not happen when I ride at lower ftp. Any thoughts, is this normal?

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**Author:** ![batwood14](https://sea2.discourse-cdn.com/trainerroad/forum/user_avatar/www.trainerroad.com/batwood14/32/30318_2.png) [@batwood14](https://www.trainerroad.com/forum/u/batwood14)\
**Post date:** [February 19, 2022, 4:56pm UTC](https://www.trainerroad.com/forum/t/physical-or-mechanical-issue/69723/2 "2022-02-19T16:56:09Z")

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Replace your bottom bracket immediately. Today.

I speak from experience. Good luck.

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**Author:** ![getbent](https://sea2.discourse-cdn.com/trainerroad/forum/user_avatar/www.trainerroad.com/getbent/32/85073_2.png) [@getbent](https://www.trainerroad.com/forum/u/getbent)\
**Post date:** [February 19, 2022, 7:52pm UTC](https://www.trainerroad.com/forum/t/physical-or-mechanical-issue/69723/3 "2022-02-19T19:52:24Z")

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Took it to the LBS and waiting to hear back thanks!