So it’s that time in the great northwest where riding outside means low temps and high chance of rain… thus the trainer in the basement is the ride of choice right now.
I have had a Cyclops fluid for a few years now and there is something I just can’t figure out. I will start warming up in an easy gear… just spinning along with plans to pick up the pace or shift to a higher gear later. It feels easy, almost too easy. Then, after ten minutes or so, it’s like a switch flips and this gear is suddenly a lot harder than it was a few minutes ago. What is the cause of that??? My theories are that the viscosity of the fluid changes somehow after a few minutes to warm up OR, that my legs just start getting tired after a few minutes and I just need to get stronger or shift to an easier gear.
I just experienced this same thing tonight on my trainer. My theory (while I was watching U2’s Vertigo Tour DVD-great concert DVD, good trainer entertainment) was that the friction on the tire causes the tire to heat up, thus expanding the air inside the tire increasing the pressure on the trainer which causes it to ride harder with more effort. My .02 cents.
Just got off the phone with Cycleops. Spoke to a guy who is new there and he doesn’t know what it is. He is going to ask around and call me back. If anyone else has anymore stories, theories, questions, or experiences with it, post now so I have all of the info when they call back. I will post after they call.
I have had the same problem, but it seems intermittent. After a little while it will suddenly get harder, but then it might go away. It also says to turn the adjustment knob 2 full turns after initial contact with tire. I barely turn it at all after the initial contact with me tire, if I turned it 2 full turns it would pop my tire and be pressing against the rim I think. I usually just set it to something that feels close to accurate or maybe a little on the easy side and adjust resistance by shifting gears.
Our Cycleops fluid trainer does the same thing. Resistance goes up noticably after a few minutes. I also find that the fluid trainer resistance is MUCH higher in a given gear than the Cycleops wind trainer we have. I’m talking almost the difference between the big ring and the small chainring difference. When we purchased the fluid trainer, we thought the resistance would be similar, just quieter. But now there is no way I can keep up with Coach Troy’s recommended gearing!
Yes, along with the others I too have this happen. Every time. ANd it’s pretty predictable too, usually takes about 3.5 minutes before there’s the increase in resistance. No explanation for it, but it’s very consistent. Just the way it works, I guess. Surprising that they don’t know about it at CycleOps, or perhaps they’re being a bit disingenuous.
this should be helpful for when they call. I agree about Coach Troy’s gearing. I have one of his videos that came with the trainer at it is a classic. It has Wendy Ingraham, Karen Smyers, Greg Welch, a young, big haired Tyler Hamilton, Ron Kieffel, Scott Moninger, among others. But, his gearing is a joke and I always get fully nauseaus even trying.
3.5 minutes is about right. I sometimes get it at less than 2. Might change your subject to Cyclops Fluid Trainer so some more owners might read and post an explanation.
look at the cyclops web site and you’ll see the power vs. speed curves for the various types of trainers. fluid is the steepest curve by far. mine always seems to get difficult after a few minutes. I figured it was just me being a wimp. A close ratio cassette like 12-21 or 11-19 for the fluid trainer is nice. I got a cheap straight cassette last year and it makes it easier to dial in a effort and cadence.
always happens to mine too, though it takes more like 5-8 minutes.
i always just figured my legs get warm and my cadence increases, thus triggering the resistance mechanism (don’t they advertise that as a feature… i alway thought i remembered that)
seems to happen when i mash down too. i often watch hockey when i ride and if i get pissed i pedal harder and thats when i feel it. i can often reduce my rate or smooth out my pedal stroke and it goes back.
A friend of mine has a Cyclops Fluid Trainer and I worked out a speed vs watt output for him. You may be interested in it. I can e-mail you the spreadsheet I prepared for him. I based it on the manufacturer’s curves. Just give me your gears and range of cadence you’ll be riding at.
How to use it?
Mount a cyclecomputer on your trainer to measure your speed.
Note the gear you are riding in.
Look on the spredsheet for the corresponding speed and gear and it will indicate your cadence and watt output.
I’ve done the same thing for my windtrainer (old Racermate from 1980). This is a “poor mans” way of knowing and logging your performance. Works great!!
By the way, a fluid trainer is MUCH MORE difficult than a windtrainer. The good thing about a windtrainer is the output watt curve most closely represents your output on the road at the various speeds (under “no wind” conditions).
This is interesting. I spent more on a fluid trainer because I had been told it more closely resembles outdoor riding resistance, and it’s quieter. Well, it’s definitely quieter but it looks like the riding feel isn’t what I had been told. It works ok. The bigger struggle I have is staying comfortable on my bikes which fit great when I am moving but they are so much harder on the body sitting still. I have to try rollers eventually.
I would love to have that power chart you offered. My gearing is 50/34 by 11-23 (10 speed) on the road bike and 53/39 by 12/25 (nine speed) on the tri bike.
Fluid trainers do more closely resemble the road, unfortunately more closely doesn’t mean accurately. I’ve sat on wind trainers that I can happily stick it in the 53-11 and spin away at over 30 mph for a good long time. I can’t do that on the road, and I certainly can’t do it on my Cycleops fluid trainer. On mine I’m struggling to hold 26mph for two 3 mile TT’s (which I don’t have difficulty doing on the road). Many mag trainers actually have resistance curves that will start going down if you get going fast enough.
So keep in mind that “closer” to road feel is definitely relative to other systems.
As for the “bump” in resistance that many feel after a few minutes, I’ve experienced that in all of the few fluid trainers that I have ridden. I think it has less to do with the fluid expanding and more to do with the Reynolds number increaseing. The Reynolds number is a unitless number equal to rho (density) * V (velocity) * D (some constant characteristic dimension for your system) / mu (viscosity). If you are cruising along at constant speed the numerator of that equation (rhoVD) will stay roughly constant while the denominator (viscosity) will get smaller as the fluid heats up (think honey–when it’s cold it’s thick as mud, but pop it in the microwave for 15 seconds and it will run all over the place). Since the numerator is roughly constant (with the assumption of constant speed) and the denomonator is getting smaller, the reynolds number (rho) is increasing. Drag (trainer resistance) will have some kind of direct relation with reynolds number though it won’t be linear. It will more likely stay roughly constant for a wide rang of reynolds numbers, then transition to a different flow regime (resistance level) over a very short range of reynolds number. This is why it feels like a switch going off rather than a slow increase. This is also why it can sometimes feel rather “bumpy” in that transition region. The range of Reynolds numbers over which this transition takes place is small but it’s steep so when you are in the middle of it the flow inside the trainer will be hopping between very high and very low resistance. This is why easing off a little bit or stepping on it a little bit will get you out of the bumpy region. Note that if you ease off a bit you may enter the bumpy region again as the temperature of the fluid continues to increase. Eventually the temperature will become constant as the energy that you are putting into it becaomes equal to the heat that the trainer dissipates.
Interesting…I just switched from my Cycleops Fluid trainer to a Blackburn RX-7 wind trainer, per disucssions with my future cycling coach. I find the wind trainer much tougher for a given gear.
By way of example: Doing Spinerval tapes, I can maintain the cadence and gear ratio he suggests when I’m on the Fluid. Switching over to the wind trainer, I usually have to drop it down at least one gear.