I have a 12sp mtb on a Direto xrt trainer I just got. It’s absolutely fantastic when it’s too cold out for the winter and works well with watching my kids. I know the gearing is pretty different to road bikes and I just can’t equate to the same speed or distance with the same power and cadence as others. When doing events I tried category c and it seems to be challenging enough, but I’m always higher than what’s asked for power wise at any given interval just to keep up and stay near the middle of the pack. Are there mtb on trainer specific groups or events? prob not common, but that’s the bike I have and the one I have available for the trainer. It’s not a big deal, but for some reason I’m still pretty competitive when I see anyone pass and try to keep up within reason without blowing my load. My trainer difficulty is on 100%. My intention is to find other riders on similar setups, not to make it easier. Even if there are no good suggestions or no such option, I’m still enjoying training on zwift with a mtb a great deal. More than I thought I would. Cheers.
Have a look at the resource Wiki: Zwift Resource Wiki 🗺
I’ll draw attention to two of the links:
…and the discussion on adaptive athletes:
The latter has more applicability than just adaptive athletes - it’s a bit of an explainer on how to use the ZwiftHacks Events database search functions. They also reference the “HERD” club which has rides that might be up your alley.
What bike are you using in the game? If you have a MTB or gravel bike equipped in the game you will roll slower on paved roads (Zwift changes the rolling resistance for different road surfaces). If you are on a TT bike in the game you dont get draft benefits from other riders.
Could you just be inadvertently slowing your avatar down?
Not familiar with Directo, so not sure if it is wheel-on or smart trainer. I used to ride my MTB on smart trainer until very recently.
Only trick is to drop the realism setting a bit from 100%, otherwise you simply spin out, even on the flats. You still need to put out the same watts required, just using a different gear.
If you’re talking about lowering the Trainer Difficulty setting, that won’t change anything on the flat roads. It will increase resistance on descents only. On climbs it will reduce resistance.
The only thing about a MTB that makes it significantly different from a road bike on a direct drive trainer like the Direto is the gearing. If the gearing is too low (spinning out in high gear) you may be able to use the QZ app in between the trainer and Zwift, which will let you increase the base resistance of the trainer. The Direto may not be already supported by QZ, but the developer (@Roberto_Viola) is usually quick to add new trainers. You can contact him by raising an issue on the GitHub page: Issues · cagnulein/qdomyos-zwift · GitHub
thanks @Paul_Southworth Yes i can add Direto to the compatibility list without any issue. Also in qz you have the gears tile that is able to add some more gears (virtually infinite) to the zwift experience! Give it a try!
Thanks for the suggestions everyone! I want to keep the trainer difficulty at 100% but maybe be able to keep up with other riders relative to our w/kg and speed. I guess I know it’s as realistic to the outside road, but it is annoying to see everyone pass in the game and have to pedal at least 1w/kg higher to keep up the same pace/speed. I think I’ll play with bias to hopefully mimic road gearing? I’ll give it a try tonight. Any suggestions by how much percentage as a starting point? Or else I’ll just arbitrarily choose a number. And yes I’m on an actual mountain bike on my smart trainer which is a direct drive type and using a mtb with my avatar. I think not only is it slower using a mtb with the avatar, but you can’t draft? Anyways, I think I just wanted to be honest with my workout choosing the mtb for my avatar as well. Seems like the annoyances I’m experiencing is purely in game competitiveness. I want to pedal at the same power, cadence, and output similar speeds. So I think I’ll switch to a road bike for the avatar. I don’t have a road bike so it would be fun to have a mock experience as if I did have that type of gearing and see how I fair against other riders of similar power and endurance. I plan on buying a gravel or road bike in the future…just not the near future. Thanks for the help again guys. I realize I’m a minority running the mtb on the trainer 
Switching to the road bike in game is probably the whole solution if your gearing is high enough. MTB can draft in the game but its rolling resistance is much higher on paved routes. Bias is only available in workouts. You would need to use QZ to increase resistance outside of a workout. On flat roads, w/kg will vary based on the rider’s weight since speed on flats is governed primarily by watts, not w/kg.