Anyone else have the Cycleops Fluid 2?

[Gfi3]

So I just picked this trainer up a few weeks ago and have logged about a dozen sessions on it. I am extremely happy with it - all the positive reviews I read were spot on so I won't go into those details.

My question is has anyone else noticed that the resistance seems to increase as the unit warms up? Everything I read suggested that this would NOT occur, but I am finding that after the first 10 minutes the resistance increases quite substantially (although after 10-15 minutes the resistance seems to level out).

This is generally not a problem as that is just my warm up period before I begin any actual workouts, but I am just wondering if it is only my unit or if others have experienced this?

FWIW - I do use a power meter so I can clearly see my cadence and speed drop off at the same power level during the warmup period. I end up upshifting twice to maintain the same power level and cadence over that first 10-15 minutes.

Thanks!

[guido]

I had a first generation Cycle-ops fluid trainer that used to heat up. It also wasn't smooth at all. I ditched it and went to Kurt Kinetic and haven't looked back...

[MattTuck]

I have one of these, but it is somewhat old now... probably 10 years I'd guess.

First, I have to say I may not be observant as you, and I don't have a power meter. That said, I have not noticed such a phenomenon in the past. I haven't been on it this winter, as I'm trying to ride outside until the weather rules that out... and the 2 additional inches of snow we got last night may be the signal that riding is done.

To me, the 'sensation' of it increasing resistance could be explained by physiological factors. Pedaling non-stop on the trainer is a different feeling than on the road when you can coast for a few seconds here and there. On the trainer, there is no break. That kind of effort on a warm up might be more fatiguing than a warm up on the road.

When I ride it this year, I'll pay more attention and see if I feel what you're describing.

[carpediemracing]

I'm not an expert on how the fluid resistance works but for the last 10-12 years I typically logged 100-150+ hours a year on a trainer. For that time I've had a Cycleops Fluid, original and then the 2. The original leaked all its fluid over some time.

What I noticed before I realized that I wasn't that much stronger but that my trainer was leaking is that the resistance increased a bit after a warm up. This is what you're describing.

Later I noticed that I could go faster/harder as I warmed up. This was just before I realized that the resistance levels were much lower. This happened to be when I first got a powermeter, so 2007 or 2008 or so.

At that point I warrantied a different Cycleops trainer I had (the e-trainer, the powermeter one) and asked for either a mag or fluid unit. They sent me the Fluid 2. I've been on that since, and it seems to be pretty consistent, meaning I struggle to use a gear bigger than a 39x21 or 19 for any length of time.

[wallymann]

fluid unit resistance *does* change as they heat up. its moderate, but does happen. i imagine the tyre heating up also affects the measured resistance as well.

i have a KK and i can/do track the DECREASE in resistance as it heats up...on some easy/aerobic workouts, i keep a constant cadence/gear/speed and watch it like a hawk...and i can see the measured wattage slowly ramp DOWN as i get further into the ride and the resistance unit gets nice and toasty.

note: edited to reflect DOWNWARD trend, not upward as i incorrectly remembered -- see chart below.

So I just picked this trainer up a few weeks ago and have logged about a dozen sessions on it. I am extremely happy with it - all the positive reviews I read were spot on so I won't go into those details.

My question is has anyone else noticed that the resistance seems to increase as the unit warms up? Everything I read suggested that this would NOT occur, but I am finding that after the first 10 minutes the resistance increases quite substantially (although after 10-15 minutes the resistance seems to level out).

This is generally not a problem as that is just my warm up period before I begin any actual workouts, but I am just wondering if it is only my unit or if others have experienced this?

FWIW - I do use a power meter so I can clearly see my cadence and speed drop off at the same power level during the warmup period. I end up upshifting twice to maintain the same power level and cadence over that first 10-15 minutes.

Thanks!

[batman1425]

I always thought that resistance from the fluid unit should decrease (if anything) as it heats up? Increase in temp should decrease fluid viscosity decreasing resistance.

That said, Cycleops, Kurt, and most other upper end fluid trainer manufacturers design their fluids to have mostly stable viscosity across the normal operating temperatures of the units. This is also why the units have heat sinks and cooling fins - to keep that temperature range as narrow as possible.

If you are experiencing an increase in resistance with increase in Temp, I would look to the tire heating up as the culprit.

**Edit** Straight from the Kurt Kinetic product description: "Unlike other fluid trainers that lose resistance when the fluid is heated up, Kinetic Fluid Trainers use thermodynamically neutral liquid silicon to ensure a consistent, measurable and repeatable workload at all temperatures."

[Neil]

They do change as they warm up - not a huge amount, but the resistance does change.

Whether it's the tyre or the unit itself I don't know, but my understanding was that the fluid resistance unit worked like a viscous coupling/auto trans, where disc spins in a fluid that becomes thicker the hotter it gets as the disc spins more rapidly.

What I do is calibrate the power meter, warm up for ten minutes (both myself and the turbo) then re-calibrate and get on with my workout.

[Gfi3]

Thanks for all the input. Sounds like what I'm experiencing is pretty normal.

[Green10speed]

I have noticed that as well. I'm looking into trying rollers this winter

[Clancy]

I have the fluid. Have never noticed an increase in resistance as the unit warms up.mi have noticed a decrease in my legs as the time goes by.

I have a love/hate relationship w that thing

[wallymann]

**Edit** Straight from the Kurt Kinetic product description: "Unlike other fluid trainers that lose resistance when the fluid is heated up, Kinetic Fluid Trainers use thermodynamically neutral liquid silicon to ensure a consistent, measurable and repeatable workload at all temperatures."

in theory.

in practice, the viscous fluid does expand a bit even at normal operating temps leading to drift in resistance.

here's my analysis:

http://brown-snout.com/cycling/tech/kk-resistance-drift-2011feb06.jpg

[batman1425]

Nice to see the data - thanks!

This suggests that the fluid in a KK is a newtonian fluid, where viscosity and thus resistance goes down as temperature goes up. KK tries to minimize that difference - by optimizing fluid composition and cooling properties of the housing. This is also what I observe on my KK.

There may be some thermal expansion of the fluid leading to an increase in pressure within the housing. However, pressure does not change viscosity of newtonian fluids save for cases of VERY high pressures, so the dominant observed effect will be from temperature - which is what you see in practice. Cool!

My understanding was that most fluid trainers behaved like this. Curious though that some Fluid2 users observe the opposite. Perhaps the formula they use behaves more like a non-newtonian fluid - increasing resistance with increased temp. I would be interested in seeing data like wallyman's from a fluid2 unit to see how they compare.

[Gfi3]

Here's some data from my last workout on the fluid 2. Note the speed vs power for the first 10-12 minutes.

http://i1174.photobucket.com/albums/r616/GFI3/Stuff/Graph_zps55c15fa5.png (http://s1174.photobucket.com/user/GFI3/media/Stuff/Graph_zps55c15fa5.png.html)

[commonguy001]

Another fluid 2 user (or former user) and mine did the same thing.
10-15 minutes and it seemed to kick in.
I don't remember how big of a difference there was but you noticed it.

Mine never leaked but I don't think the model I had was known as one of the leakers.
Don't really remember when I got it but if I had to put a year on it I'd guess 2002.

[cderalow]

I've noticed mine gets slightly more intense as it warms up.

Maybe if i get bored tonight I'll run a constant cadence/power test on it for s&g's

[gmcampy]

So I just picked this trainer up a few weeks ago and have logged about a dozen sessions on it. I am extremely happy with it - all the positive reviews I read were spot on so I won't go into those details.

My question is has anyone else noticed that the resistance seems to increase as the unit warms up? Everything I read suggested that this would NOT occur, but I am finding that after the first 10 minutes the resistance increases quite substantially (although after 10-15 minutes the resistance seems to level out).

This is generally not a problem as that is just my warm up period before I begin any actual workouts, but I am just wondering if it is only my unit or if others have experienced this?

FWIW - I do use a power meter so I can clearly see my cadence and speed drop off at the same power level during the warmup period. I end up upshifting twice to maintain the same power level and cadence over that first 10-15 minutes.

Thanks!
+1 but its not an issue for me, I just watch power meter and maintain the zone I want to ride in by shifting/cadence

[malbecman]

+1 but its not an issue for me, I just watch power meter and maintain the zone I want to ride in by shifting/cadence


Same here!