tru-trainer and e-motion watts

[david]

i'm looking for an indoor training device to supplement my computrainer.

was thinking of getting either the tru-trainer or the e-motion. i was hoping to get a sense of what kind of resistance is required for each machine. each site has some figures, but i was hoping for real-world feedback.

on the e-motion site, they have a neat excel spreadsheet that allows you to determine how many watts you'd be putting out in a gear at specific rpms.
for example, at 90 rpm in a 39x23, you'd be putting out 174 watts.
in a 39x17, 272 watts.
in a 53x17, 374 watts.
that's without the magnet on at all.

with the tru-trainer, they have a simple chart that seems to indicate that at 25 mph, you'd be putting out 250 watts. or 225 at 22 mph.

for those of you who have experience on these systems, does the power data seem accurate?

thanks

[11.4]

I've ridden both rollers with an SRM powermeter and neither data presentation is particularly accurate. Wattage isn't necessarily related to rider mass either since you aren't actually moving the mass anywhere, but you definitely do exert different amounts of energy depending on your mass. Riding style, smoothness, gearing vs. cadence, level of tiredness, and other factors affect wattage output to a significant degree as well. The ideal way to figure this out is to borrow a powermeter and run a series of tests at different gears and different cadences. With the TruTrainer, run the tests both with the flywheel engaged and with it disconnected. Anything else is so inaccurate as to be misleading and detrimental to your program. As I've suggested on another thread, you can get early generation Powertaps at dirt-cheap prices. For a wheel for a roller or trainer setup, they are just fine, and you will then have accurate data.

As for comparison, there is a fairly significant different in load between the rollers but it occurs in different ways. There's a noticeable load on the e-motion at all speeds and regardless of whether you are accelerating, while the flywheel on the TruTrainers imposes more load during accelerations and then eases off a bit at constant speed (more like actual road riding).

I wouldn't choose one of them just for the resistance setting. Search some recent threads on these rollers. I'm a strong proponent of the Trutrainers relatively to the e-Motions.

[1centaur]

While I can't answer the original question specifically, I can add some filler to 11.4's comments that I think will help make the decision.

I bought the e-motion rollers a few weeks ago to supplement my Computrainer. I was looking for something to smooth out my stroke and add diversity to my indoor workout rather than something wattage based. I picked the e-motion in part because the decibels were supposed to be low, in part because the motion was supposed to be a bit more road like and in part because I liked the idea of a margin of safety as I learned to ride them.

I have been very happy with them so far. However, I concur with 11.4's comments about pedaling with more drag than the road. The action feels more like a time trial where just rolling along is not the point. There's a smooth, even force to overcome with your stroke (not too unlike the CT) and the motion of the rollers forward and back tells you if you are doing a good job of keeping an even stroke. I have stayed in the 39 ring so far because I don't use the rollers for wattage training, and that's my biggest point here: the CT is well known as an accurate watts meter and is well suited to all sorts of power-based workouts. I don't need that function from rollers, I only need what the CT does not provide - tactile (as opposed to the less useful SpinScan) feedback on how well my stroke is being produced. I can certainly get lots of resistance from the e-motion's 4 resistance settings, and as my EVEN stroke becomes more powerful I'll have plenty of opportunity to move up in resistance, but for now I view the rollers as a technique improver, not a wattage opportunity. I don't even turn on my FlightDeck to see my speed.

BTW - If you were doing 90 rpm in the 39-17 on the CT I don't think you'd be doing 272 watts.

FYI - My wife is insisting that I mention here that she built a fabulous platform around the rollers that allows me to get on and off the bike without drama. She built it like a carpenter, painted it black, attached a rug to the step so I don't slip, and she signed it. I recommend a platform for any rollers, but no, she won't take commissions.

[Too Tall]

1Centaur - Dewd, you married up ;) Nice nice nice, she's a keeper.

I ride the e-motion with SRM sometimes however mostly use a track bike with 72" gear. In both cases I do not pay attention to watts however with the magnet swung out of the way the e-motions feel pretty free rolling to me.

The TSS score from a 1 hr. roller session is pretty well dead on same as riding to and from work. They do not "feel" harder to ride than a flat road with no headwind. Wow, now that's scientific huh ;)

E-Motions are not as free rolling as Krietlers but certainly not alot of resistance. Anywho I am not looking for a power workout or tons of resistance on rollers. Riding aerobic and tempo is my game...some hard intervals 3/5mins is all nothing fancy. You should not worry about this aspect with either product from what I know.

[david]

thanks for the thoughts, guys.

sounds like both devices will allow for a nice roller-like session and also some power work, too.

while i mentioned that this purchase would be supplemental to my computrainer, it will actually be more of a substitution.

my plan is to have it at my office. i work stupid hours and sometimes it's just easier to squeeze in a session at 7 or 8pm at the office and then finish work than it is to try to get home and ride at 11pm.

anyway, another computrainer would work well, but they're about twice as expensive and a little variety wouldn't hurt.

11.4, you mentioned that you like the more road-like feel of the tru-trainer. that sounds good. but i love the idea of being able to get out of the saddle and sprint. that has me leaning toward the e-motion.

my only reservation with the e-motion is that their literature suggested that the machine requires quite a bit of power to turn over the gears. their srm measured figure of 272 watts to turn a 39x17 at 90 rpm spooked me a bit. 1centaur, you're right... i would definitely not be doing 272 watts on the computrainer in that gear at those rpms!! that's why i thought it seemed a bit extreme from a resistance standpoint.

as long as i can get some low resistance roller action combined with some power work when i want it, then i guess it doesn't matter what gear i'm in.

maybe i've just had too much coffee.

[11.4]

11.4, you mentioned that you like the more road-like feel of the tru-trainer. that sounds good. but i love the idea of being able to get out of the saddle and sprint. that has me leaning toward the e-motion.


You can definitely sprint out of the saddle on TruTrainers. You can also do a no-support start on the TruTrainers with a road bike, because the flywheel helps keep the wheels spinning while you clip in. I've done (nearly) standing-start jumps and flying jumps on a track frame on the TruTrainers, both with and without the flywheel connected. For what you describe, I'd definitely recommend the flywheel disconnect option, by the way.