Beginner - Gearing advice needed

Right, so I’m a new cyclist and in training for next years Ride London so I have put my road bike onto a Tacx Flow Smart trainer to use with Zwift. My question is what gearing is the most sensible to use when riding?

My bike has 50/34 on the front and a Shimano 8sp cassette 12/25 on the back (700c wheels).


Hi @Richard_Cleverley.

You can use any gearing that you are comfortable with. Most people prefer to use the same as they use on the road.

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Thanks @Gerrie_Delport When on one of the training modes, it gives me power levels to match, I’m just wondering whether it’s best to use gears to keep to the power levels rather than slow my cadence down? Should I try to keep my cadence steady and match the power level by using my gears?

If you are referring to ‘erg’ mode, the gearing really doesn’t matter. In erg mode Zwift is looking for a certain power output from the rider, so if you change your cadence and/or shift gears the trainer resistance will adjust automatically to compensate so that your power output remains constant. (There are, of course some fluctuations, and the trainer also takes a moment to respond to each change.)

As for gearing, Gerrie is right that you should use what you are comfortable with. If you look at the ‘Difficulty’ slider in the settings, 100% will equate to feeling the gradient changes as you would outdoors (or at least as closely as Zwift can mimic them). If you slide it all the way down to zero you won’t feel any gradient changes at all (in the trainer). And in the middle (50%) you’re sort of splitting the difference. Zwift’s example is that with the slider at 50% an 8% grade in-game will feel like a 4% grade IRL. Whatever difficulty setting you choose, though, Zwift will still require the same wattage output to make your avatar move at a particular speed on a particular grade.

So why even have the difficulty slider? The reason I hear most often is that some people just don’t have the gearing on their bikes to tackle the steeper grades in Zwift at the 100% level in a comfortable manner. So, virtually decreasing the grade allows them to pedal at a reasonable cadence (even if their avatar might just be crawling along in-game).

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Thanks @Nigel_Tufnel

That’s really useful. When I was talking about power levels, I was referring to things like the FTP builders in the training mode where it gives you power output targets like 110W or 80W. Obviously, when you change from a 110W section to 80W section you can either drop your power output by reducing your cadence or by changing your gear down and keeping your cadence steady. I’m just wondering whether there is a preferred way of doing this from a training point of view?

I am no coach but I would rather change gears. I aim to keep my cadence in the same zone.

Thanks @Gerrie_Delport

That’s what I thought, great to have someone confirm it sounds right.

I don’t have a Tacx Flow, but it is listed as a smart trainer. To me this should mean that the trainer can adjust the resistance to the terrain in Zwift (in sim mode) or to what you are doing on the bike (in erg mode). So, if you’re doing a workout and the specified power output changes from 110 watts to 80 watts you should truly have to do nothing. If you maintain the same cadence and gear the trainer should adjust its resistance so that you are putting out 80 watts. If you change your cadence and/or gear the trainer should then also adjust its resistance so that you are still putting out 80 watts.

One of the ‘joys’ of erg mode for workouts is that you can just select a gear (any gear) and the trainer will adjust the resistance so that you have to put out the specified watts to match what the workout wants. And for a given power output if you speed up your cadence or change to a harder gear the trainer resistance will decrease to keep the power output constant (perhaps with a little lag).

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Best explanation I’ve heard of the reason for this setting!