Baseline resistance too low in SIM mode


I’ve done a decent mileage so far on Zwift, member for almost 2 years now. Using KICKR 2018 Smart Trainer (+CLIMB and HEADWIND) and running Zwift on MacBook Pro (late 2013 model).

Until today, I’ve been using ANT+ FE-C connection, which suddenly failed (probably moisture in the dongle), so I’ve switched to Bluetooth FTMS. I’ve immediately noticed a massive difference in the resistance, that’s set by Zwift - it is suddenly much, much lower. I’m basically always in the hardest gear regardless of the incline, changing to easier only when it get’s above 4%. I can’t reach my peak power (1000W+) without ridiculous cadence and half of my cassette is now useless. That wasn’t an issue previously via ANT+.

Now my bike setup is a bit unusual - I have a 26” MTB hooked on the trainer, it’s 3x11, chainring is 40-30-22 and the cassette 11-40. So you might think undergeared - which I agree, but to my surprise was somehow never a problem on ANT+ connection. My FTP is 287, so I was able to reach 60kph sprints in 40x11 gear with a reasonable cadence. Now I’m barely doing 40kph in 40x11 / 90rpm at my FTP and as soon as I switch to next easier gear 40x13 I immediately spin out and the power drops to 200-ish. I can do most climbs in 3rd or 4th gear on 40 chainring. Out of 11!. Trainer difficulty is always on max.

I’ve seen a few posts at various places about small differences in baseline resistance between ANT+ and BLE. This is much more pronounced and very different experience.

Any idea why that might be the case? Anything that can be changed somewhere to make it same as it was? Or is swapping for a road bike the only thing I can do now, in this what seems purely software issue? If ANT+ connection could generate “additional” resistance to somehow level up my MTB to somehow a road bike experience, why can’t BLE connection achieve the same? Is it Zwift problem? KICKR problem? FE-C vs FTMS problem?

Any help appreciated.

Watching as this sounds similar but not identical to the issue I raised yesterday - baseline resistance is different between my old Tacx trainer and new Kickr Core - however for me it’s same issue over BLE and Ant+ for the Wahoo.

Yes, I posted about this a while back (I ride a Kickr) — at least 2 to 3 gears bigger riding Bluetooth vs. Ant and there was a link posted to a specific explanation of this pertaining to Wahoo Kickr and its firmware.

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Thanks William. I’ve passed that on to Wahoo and Zwift and it’s been suggested I also create a feature request, so I’m gonna do that.