General Tips for keeping up on a single speed/fixed gear

Hi All, I have a Saris M2 smart trainer, new Zwift as of this past winter and it’s been all around awesome! A life saver in fact. However, now that I’m getting stronger and faster, D. Diesel is too slow to be much fun anymore. I can keep up to C. Cadence on the flats and have trouble letting her “keep up” on the uphills, however, as soon as there is a downhill for more than about 15 seconds, the group is gone.

The thing that doesn’t make sense is, during these downhills, I can put out 4+ w/kg, spinning at over 100rpm, but still the entire group just shoots off and they are only putting out 1.5-2.5w/kg according to the on screen display. I try adjusting the trainer intensity, but it doesn’t really help that much either by the time I get the settings changed.

I know it’s not because I’m too slow (I’m not bragging as I know I’m also no powerhouse) because I can usually outclimb or out-flat(?) most people in a ride who are around my same skill/level.

Anyone have any tips as to what I can do in general?

Trainer makes no difference. Single/fixed gear makes no difference. Trainer intensity makes no difference.

It’s a simple speed/watts/draft equation. There is no reason why you should be getting dropped doing 4w/kg going downhill when everyone else is doing 1.5-2.5w/kg unless you are exceptionally light, riding the time trial bike (so not benefiting from any draft) or you are out of the draft of the group over the top of the hill. If you are too far ahead you may have paused pedalling to wait for the group who will then blast past you on the descent before you’ve been able to get up to speed to match their pace. On the other hand, if you leave even the smallest of gaps to the rider in front over the top of a hill then you will be dropped like a stone as the group draft makes groups insanely fast on downhills to the point that it’s almost impossible to catch them even if you are doing 4w/kg.

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Thanks for the reply, it could very well be that happened, but it would also mean it happens every time? I’m not discounting that completely because I’ve not paid direct attention to how close I am to people going over a hill. I’m not using a time trial bike (never do), I weigh 162lbs, which I think is on the lighter side as I’ve always been lighter than my peers.

I will also add, that if you think about it, in real life a fixed gear wouldn’t be able to keep up to a geared bike simply because your legs hold you back, however Zwift doesn’t necessarily know this. But I wonder if it’s sensing my legs essentially “braking” midway through the stroke and registering multiple small drops in power and if I’d be better off just getting up the hills and coasting (IE: stopping pedaling altogether) down?

Have you compared your cadences in/outdoors or tried a higher gear for the trainer? I guess it depends on the trainer and what else, but I for one certainly find that I spin out easily if I use a similar gear on the trainer that I have on my singlespeed.

I’m kind of late to the party, but I’ve been riding a fixed gear on Zwift since 2017 using a Stages power meter (DA track crank) and Elite smart trainers, including the last month on a Tuo. I agree with Aoi, who has done an excellent job in explaining the parameters and the likely causes of the problem.

I would add that the wattage Zwift shows onscreen when you are descending at 4+w/kg should be over 300 watts. If not, you need to check the weight you’ve logged in for metric units is around 73kg and not significantly lower. Also, make sure if you’ve selected imperial units as the measurement that you input 162 lbs as your weight. (If you input 73 lbs, this is probably the source of your problems.)

Otherwise, it’s not that unusual when you are riding at the back of a group of heavier riders for this problem to happen. I’m 150 lbs or 68kg and I sometimes have to put out 3-4w/kg just to hang on the back of a big group on a long descent. To avoid this I just make sure I’m near the front half of the pack before the descent starts and put out the effort to stay there when it starts.

You may have another problem which isn’t the cause of this problem since Zwift is using the wattage reported by the paired power meter to calculate your speed. However, the wattage is probably inaccurate if you are not using a separate power meter like a Stages crank or Garmin Rally pedals as your power source. If you are using the M2 as your power meter, you need to do a roll down or spin down using the Saris app after a 10-15 minute warm up. This is almost impossible to do on a fixed gear bike because it requires you to pedal up to a speed over 30kph and then stop pedaling and let the rear wheel coast to a stop on its own. Since you have no freewheel and are on a fixed gear and not a singlespeed, the only way you might be able to correctly do this (and avoid injury) is to use platform pedals where you could just lift both feet off to start the spin down, and try to maintain your balance on the saddle without them.

I suspect your uncalibrated M2 is reporting higher wattage than a properly calibrated power meter would. Keep in mind that you can’t just use a single speed or freewheel/derailleur bike to calibrate the M2 and then mount your fixed gear in its place because it has to be the same tire that is used in warm up and the spin down procedure if the calibration is going to have any accuracy.