CycleOps Fluid 2 resistance

cc78

Here's the situation: I end up having to move my training location around quite a lot, and as a result the CycleOps Fluid2 trainer gets picked up, moved about, etc etc. My question is can this affect the stability of the resistance?

I use it with TrainerRoad virtual power. My schedule is a little erratic although I usually manage 2-3 sessions per week. About 10 days ago I was able to comfortably hold 300W for 8 minute intervals with my heart rate sitting around 165bpm... today I struggled to keep it at 230W under the same conditions, which seems a huge discrepancy. Tyre psi is the same and I always tighten the resistance drum to the tyre until the ratchet clicks as per the CycleOps instructions.

Does anyone else with the Fluid2 have similar variations?

C_P_

if i start an interval at 260w and a cadence of 90 and hold it for 8 minutes by the end of the interval i'm doing 290w with my quarq elsa and fluid 2. i've alwas had to change gear or cadence to maintain constant wattage. thats the trouble with virtual power you're not doing what you think you are because trainers aren't consistent.

jgsi

It needs 10 to 15 mins warming up.... thats all.... nothing to see here , move on

cc78

thanks for the comments... yes I appreciate virtual power is not 100% accurate but I haven't had such big fluctuations in the past

re warming up, what do you suggest? 10 minutes light spinning before starting the session?

buckmulligan

This is a common problem with the Cycleops Fluid 2. You'll find loads of threads on various forums about it, but to cut a very long story short, the resistance of the Cycleops Fluid 2 trainer goes through the roof as it heats up. I don't know why this happens, perhaps the fluid increases in viscosity with temp, the metal parts of the unit expand with the heat, or something else; I tried contacting Cycleops themselves and unsurprisingly they refused to acknowledge the issue.

This issue in itself would be manageable, but obviously the rate of heat-dissipation from unit varies hugely depending on the ambient temperature, the wattage that you're holding, air-flow etc etc etc, so using it for any kind of structured training is useless. JGSI's comments regarding a 10-15 minute warm up are misguided; that might mean you get stable cadence-VP readings for a steady-state workout at a particular wattage at a particular ambient temperature but the VP values won't correlate well with your VP-tested FTP or other high-intensity workouts, nor will they be consistent over time. Even with a stable turbo trainer setup protocol (tyre pressure, roller compression etc) you're not going to get anything close to consistent with TrainerRoad's Virtual Power, trust me, I've tried extensively!

After about 4 weeks of banging my head against a wall trying to get reliable results out of my Fluid 2, I bought a Kinetic Road Machine and never looked back. That thing works flawlessly with TrainerRoad's Virtual Power, which I can attest because I've tested it several times against my Quarq.

As a minor addendum, there are reports of people using older models of the Fluid 2 successfully with TrainerRoad's Virtual Power; I have no reason to doubt the rigour of their experiences, so I can only assume that something has changed in recent years (e.g. the fluid used in the trainer? degradation of fluid viscosity over time? changes in manufacturing tolerances of the impeller in the resistance unit?)

If you want to read more, have a look at the threads below; I'd advise ditching it and buying something else, it's just not worth the hassle.

http://forum.slowtwitch.com/forum/Slowt ... F_P5797730
http://forum.slowtwitch.com/forum/Slowt ... _P5774638/

cc78

@ BuckMulligan

Thanks very much indeed for your input; makes a lot of sense.

I guess an interim fix might be to run the TR workouts with heart rate instead of VP... would maybe work for longer sweetspot/threshold intervals but obviously not sprints and so on.

I'll have a look for the Kinetic Road Machine as a long term solution.

Thanks again.

jgsi

Explains then, why I am consistently popped after an hour's Zwift racing..... the bike has a power meter and good to know that my energy levels have been so sapped by a dodgy trainer ..
In reality , the Fluid 2 for me has given a good resistence feel that is consistent.. my only complaint is that it is noisier than I'd like it to be.

Each to their own.

buckmulligan

As I said above, some people (seemingly those with older models of the Fluid 2 in particular) report a nice consistent power-to-speed profile, which is great and can be used to great success with things like TrainerRoad's Virtual Power or Zwift's Z-Power; I've no reason to doubt the veracity of their claims at all. On the other hand, there are plenty of reports (seemingly those with newer models of the Fluid 2 in particular) that rocket in resistance at a given wheel speed at a seemingly inexorable rate. I experienced this myself and it's not something that you can really overlook if your unit does it; for me it crippled nearly every workout that involved an effort >200W.

Another point that I'd add to the OP, you say that you "tighten the resistance drum to the tyre until the ratchet clicks", in my experience the ratchet-knob thing isn't a great design either and will give inconsistent results depending on how much inward pressure you're putting on it. Tyre pressure and roller compression are two very critical factors in using Virtual Power, so you have to be as consistent as possible. I usually pump the tyre up to a set PSI (e.g. 90), spin the rear wheel and then tighten the roller until it just makes contact with the tyre (usually at one specific spot if your wheel isn't perfectly round!); then tighten the knob a set amount (e.g. two full turns) to put a decent amount of pressure on there. You can also put a mark on the knob to see whether it's consistently in the same place each time you set it up. That might help solve some of the inconsistency between setups, but as you can probably gather now, my experiences weren't good and I suspect you're fighting a losing battle!