Single speed on a smart trainer with ERG considerations

I am checking to see if there are any potential problems or anything I should know / consider before I fully commit. Here is my plan:

I am going to purchase a smart trainer (Elite Direto) to use in ERG with a single speed mountain bike. I will install a single speed cog and spacers on the trainer for a proper chain line as I would with a rear wheel (so the chain line will be straight) and use the adjustable dropouts on the bike to tension the chain.

This will become my winter trainer setup for all of my TrainerRoad workouts. I think it should be just fine, but wanted to check to see if anyone has any thoughts or recommendations.

Thank you in advance.

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You should check out the zwift cog setup.

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I have looked at it, but it doesn’t really do anything more than any other smart trainer except the simulated shifts. I don’t need any shifting or shifting feel / feedback for my training. I just need repeatable power measurement from workout to workout.

I guess if you’re buying a trainer then I’d go with the Zwift thing for more options down the road but your plan seems fine if that’s what you want.

Just make sure that the bike fits on the trainer. My old 7 speed bike was too narrow for my new trainer.

You may also need to check your gear ratio against the capabilities of the trainer and the sort of watts you’ll be pushing, as too high or too low a gear could see you hitting the wattage floor/ceilings of the trainer which can be frustrating.

Crownan, this is something I was curious about. How or where do I find information like that?

How does that work? The trainer brakes against what you push (regardless of gearing) to give you the desired resistance. The only thing that you may find is that with a big gear, the flywheel inertia will be high and will feel different to a slower speed i.e. less responsive, can feel easier to complete workouts

They can only supply so much resistance at a given fly wheel speed. So if you’re in too easy a gear, it will only be able to get to X watts at a given cadence. And similarly, if you’re in too hard a gear, at a given cadence it may not be able to drop down to the desired watts. Depends on the trainer.

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I don’t know if it would be an issue on a high end trainer, especially if your single speed is within the realms of “typical” gearing, rather than being extreme one end or the other. But its just something to consider.

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I have Direto my self and usually I stick on one gear on TR rides, on some cases I notice* to reach wattage floor during interval rest section.
*I did notice this on post ride analyze, that wattage did not drop to rest section target but was kept slightly above.
But to throw some numbers I did google Direto power curve and found one table/curve which seemed to be realistic.
So here are key numbers for speed and min/max power which should work:
15kph 52…424W
20kph 75…653W
25kph 101…890W
30kph 123…1130W
35kph 186…1280W
By these numbers you should evaluate your power targets vs your gearing vs your desired cadence.

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Calculate and post your gear inches (or meters of development) or post your front and rear gear sizes here.

Hopefully someone else with your trainer can give you some feedback based on that.

I use my singlespeed mtn bike on a Wahoo Kickr without issue. I just use the cassette that came with the trainer and picked the gear that gave me a straight chain line instead of the single cog and spacers. It has been flawless.


I’m not reading through all the replies but if you are only going to use ERG mode, you don’t need to worry about having just a single speed cog or functional shifters or anything. I have a gravel cassette on my trainer bike paired with an old non-functioning mtb derailleur and two old brifters (for hand placement) that aren’t connected to anything. I just have the chain sitting in a middle cog. So just throw any old cassette on there. I suppose you don’t even need a derailleur as the poster above showed if you have a way of getting good chain tension. the setup doesn’t need to be functional for outdoor riding, just a decent gear combo and chainline.