Spinning out on a flat Zwift race?

In my most recent Zwift race [ DIRT Doozy Race ( C ), 5:55 AM Feb 4, 2020 ], something happened that I’ve never experienced before on Zwift.

Pretty much throughout the race I was on the edge of spinning out - on the big ring 50T w/ small cog 11T, averaging 24.9 mph with a 101 rpm ave cadence, with a maximal 5 second average of 197 rpm (end sprint).

My normal cadence in races or competitive rides is more like 85-90 rpm with a max of 130-150.

It felt like I had spun out (run out of gears) at the end. So I couldn’t really bear down on the pedals at the end like wanted to because I couldn’t shift higher.

So, was this all just an artifact of the flatness of the course [Tick Tock]? Or perhaps something was not right with my trainer [Saris M2 that seems to work fine otherwise].

Is there someway I can {legally!} remedy this so I don’t run out of gears/spin out at the end of a flat race? Whatever fix there is, I’d want to to not interfere with the realness of the races and equity/parity during group rides and meetups that I go on during winter Zwift months.

Thanks in advance,


Hi @Dave_Purdy_DIRT_Grin

Welcome to the forum.

A good start is to tell us more about your setup.

Hi Gerrie and thank you,

My setup is:

  • Windows 10 box (w large monitor - probably not of consequence)
  • ANT+ usb adapter (bought off of eBay, but has been functioning flawlessly for the last month, nary a hiccup, TTBOMK)
  • Saris M2 trainer
  • iPhone mounted on handlebar so I can further control with
    • Zwift Companion
    • VNC client
  • Generic carbon framed bike
    • Shimano 105 - 11/34T cassette
    • FSA 50/34T chainrings
    • FSA 172.5mm cranks
  • Bike & trainer are mounted on a rocker plate

When I was spinning out, my cadence was 195-200 rpm and my speed was about 29mph. 200rpm is pretty high, but I’m on a rocker plate so it doesn’t feel as jittery.

The iPhone connects to the same wifi network as the W10 box.

The W10 box and Zwift client are connected to the M2 by ANT+.

A further piece of data is that later this morning while I was doing a post-race recovery ride in Z1, the Zwift power indicator (upper left of Zwift window) seemed to freeze at 104W, pedaling with less or more power didn’t affect the indicator. I eventually got off the bike, and power cycled and re-paired (not repairing, but unpairing and re-pairing the connection) the M2 and readings returned to normal. Perhaps this is a red herring… ? But I’ve never had this happen before, either.

Thanks & regards,


195 - 200 RPM?
Did you mean HR?

Hi Tim,

I meant precisely 195-200 rpm - held that for about 5 seconds. That is a furious pace for me, but I felt like I had to do it (and bear some pain) as I was out of gears and and didn’t want to get passed by everyone during the last 10 - 15 seconds.

Despite the insane cadence, I couldn’t generate more than 370W, which is kinda paltry. I just could not create enough leverage against the pedals. Normally my peak power is between 750 and 850W.

My HR after the sprint was peak at 163bpm, which is about right for those of us in our late 50s.

Sounds like tire slip, or maybe the M2 is overheating. Are you tensioning your tire against the roller correctly? And also making sure your tires are inflated to the correct levels before every ride?

I have a CycleOps (Saris) H2 and a few times the trainer locked at a random wattage (like 183, 204, 243) while I’m riding and no matter how fast I was spinning it had no effect. It took like 2-3 minutes to realize that the wattage was frozen. By luck I was able to stay with group but eventually got dropped when they picked up the pace. If I recycled the power (switch on power cord) fast enough during the ride, everything returned to normal and I regained control of trainer and a few times I was able to catch up. I wonder if this is what happened to you also. I’ve had the trainer for over two years. logged over 8,000 miles and it only happened like 3-4 times, very rare, really don’t know the cause.

@Jeremy_L , thanks for the ideas - but I calibrated w/ the Saris app before each ride. Tire pressure was normal and no slippage. The wheel was whining at a high pitch, but just proportional to its rotational speed. It’s pretty snug.

Thanks @Miro_Kubinec_EVO, this sounds very much like the 2nd half of the weird experiences today. The “first event” where the trainer seemed to be misbehaving during the race was probably a clue that I should have power cycled it and the computer both before going on to the recovery ride where I experienced that “second event” with the wattage freeze.

I have about 4k-5k miles on my Saris M2, and this is the first time I can remember this happening. Definitely a rare event.

This experience has taught/reminded me a few things :

  • use the Forum - there is a large community here and a lot of experience
  • power cycle the computer (I didn’t do this, but it would make sense to) before any important ride or a race
  • continue to calibrate like @Jeremy_L mentioned - thanks JL
  • watch the M2 for any sign of failure : I live near Madison and Saris/Cyclops is just 15 miles from my home… If I need service they are closeby
  • it would really suck to be in a race and be headed for a personal best only to be stymied by hardware or software failure!

Just for the sake of completeness, are you sure the trainer difficulty setting in Zwift hadn’t “magically” set itself to zero?

PS. Kudos on the 200rpm! I’m trying not to imagine what that must have been like…

@Dan_Thorpe_7431, that’s something that I’d checked - good call on your part.

Regarding the 200rpm Club, this was on a rocker plate, and I’m not confident that I can translate that performance to outdoors in an either safe or dignified manner. :laughing: