Lemond Watt Box 3

When the Lemond Revolution trainer was first introduced, there was a lot of talk about the benefits of no longer needing a rear wheel for your bike when it was on the trainer. There was one big negative though, without the rear wheel that meant rear wheel mounted computers or Powertap hubs couldn’t be used. For cyclists that are using wattage based training that was a deal breaker. Yes, for a while Lemond did offer the Power Pilot computer system, but it didn’t really seem to catch on with its $439 price tag. Enter the Lemond WattBox. Not only is the WattBox almost half the price of the Power Pilot at $249, but the WattBox calculates the power in trainer mounted box, instead of the head unit like the Power Pilot. That allows you to use your favorite ANT+ compatible head unit or ANT+ certified smartphone apps.

Crank up the power next.

Lemond Watt Box

As mentioned in our report from Interbike, the nice thing about the WattBox is that is it compatible with both the new 1.1 Lemond Revolution trainers, but also the original 1.0 models, so as not to leave anyone out. Mounted on top of the Revolution trainer, inside the WattBox is an internal processor that will take temperature, humidity, altitude, and RPM into consideration, and outputs an accurate power reading. Lemond states that the one constant is the amount of air that each blade of the flywheel displaces. While the volume of the air will never chance in a controlled environment, the density of the air will change which is why the temperature, humidity, and altitude are considered.

“The new LeMond WattBox uses several sensors to accurately determine the power being generated by the rider,” said LeMond designer Evan Solida. “The resulting data is then transmitted via ANT+ to any compatible head-unit where the watts will be displayed.

“First, the aerodynamic resistance is determined by measuring the speed of the flywheel and also involves a function that measures air density,” Solida added. “Mechanical losses are also considered as the belt used to spin the flywheel has a mild temperature dependence and there is a slight bit of bearing resistance. Finally, mechanical resistance from the drive-train is entered into the equation.”

Riders wanting cadence can add any ANT+ cadence sensor that is recognized by their head unit. While cadence isn’t required for the WattBox, it will result in more accurate power measurement and will keep the unit from showing power when coasting.

Lemond Watt Box 2

WattBoxes are available through the Lemond website for $249 for the trainer mounted sensor. Head units, cadence sensors, and trainer sold separately.



  1. “While cadence isn’t required for the WattBox, it will result in more accurate power measurement and will keep the unit from showing power when coasting.”

    So all if you have to do is soft pedal and it will continue to read 300 watts until the fan slows??? Sounds like the only time this would be accurate is steady state conditions.

  2. Corey-

    Not entirely. If you have an ANT+ cadence sensor on your bike, it will broadcast to any compatible unit. For instance, your Garmin will display the cadence while the Watt Box receives the same data and adds it to the formula being calculated inside. The only thing cadence does is to let the Watt Box know that you have stopped pedaling entirely. If you are soft pedaling, the Watt Box will show the correct wattage even if it’s only 50 watts. Now if you actually stop pedaling completely, the Watt Box will register a value higher than zero until the flywheel stops.

    The Watt Box’s algorithm does an amazing job at determining wattage during acceleration. It’s not just steady-state by any means. As for cadence, we came to the conclusion that although it’s a nice to have feature, it’s not absolutely necessary since you’re typically pedaling the entire time while on an indoor trainer.

    Hope that explains things a bit better.

  3. this thing is as loud as a jet engine. If were called the Trek revolution trainer or the specialized revolution trainer there would be some serious hate about the whole thing

  4. Nick, if this trainer is the best investment you’ve ever made, I’m afraid to say you are really not very good at investments.

    As others have said, this thing sounds like a jet engine right after takeoff. Much much prefer the Kurt Kinetic. Yes, I have to use a wheel with it, but at least I can have peace with my neighbours

  5. True, the Revolution is far from being silent but is also the only trainer that offers a true road feel. Personally, I’ve ridden everything from rollers to magnetic (remember the Performance Travel Trac series?) and fluid (Kurt Kinetic.) Rollers didn’t offer much in terms of resistance but that’s not really the point. Magnetic was very choppy and made training indoors akin to pulling my toenails out. Fluid was pretty good and fairly quiet but still lacked the flywheel effect that the Revolution has. When riding outdoors, you’re pushing through the air. The increase in resistance is not linear. Going from 15mph to 20mph is far easier than 20mph to 25mph. Since the Revolution is utilizing the same medium for providing resistance, it feels natural while pedaling.

    The best way to describe the feel is to simply say it urges you to ride harder and longer.

  6. Without a wheel on the trainer and using a Garmin 810 and Garmin speed/cadence sensor (mounted where it has to be mounted on the chainstay to pick up cadence from the left crankarm), how does the Garmin pick up speed? Answer: its does not, because neither the WATT BOX nor the Revolution are sending that information via ANT+. What this means is that the Garmin device does not record speed or distance (or more correctly the flywheel’s equivalent thereof). In fact, the Garmin device wants to go into sleep mode, because it does not detect motion. This makes this system (Revolution + WATT BOX) effectively useless for anyone other than those who merely want to keep track of time, power, and cadence during a training session. It is difficult for me to understand why the WATT BOX does not also send speed/distance via ANT+, since it is clearly using angular velocity and acceleration as part of its power calculations. It is also a little frustrating to have to learn this myself after purchasing both.

  7. @timmy, @FJ, That is a big exaggeration which everyone keeps repeating.

    Do you actually know how loud a jet engine is during takeoff? It’s about 140dB. For comparison, a jackhammer or chain saw runs at 100dB. Decibel is a logarithmic unit. When the level of a sound is increased by 10dB, the subjective loudness roughly doubles, whereas the sound power actually increases by a factor of 10. The Lemond Revolution is nowhere near that decibel level. It sounds more like a vacuum cleaner (80dB – 90dB) when use at full speed. It’s not even close to a jackhammer much less a jet engine.

    I would not use this trainer if you live in an apartment with sensitive neighbors but if you have a house with a separate room for exercise or a garage, this trainer will do just fine and it is the best at road feel than many trainers that I have tried.

  8. @David

    Mark seems to have a better technical grasp of things than myself. That said, I have the watt box and have tried numerous times to have it display speed and distance info to my Garmin Edge 705. It appears to only display power. I purchased the trainer and watt box for its simplicity (no electric outlet or computer / iOS device required), thus far, getting the watt box to work as described on their webpage and facebook forum (i.e., displays EVERYTHING but cadence via ANT+) has been a problem.


    Are you positive that the watt box does not send speed/distance info via ANT+? The folks at Lemond say it does and some folks have gotten it to display that info. I am just wondering if we may have received units that are defective.

  9. I’ve been riding the trainer with the watt box for about 1 week. I really like the trainer. I recently synced my Garmin 500, but I can’t get it to display speed. I’ve got cadence and power, but not speed. I continue to communicate with Lemond customer service, they’ve been helpful, but I still can’t display speed. Still a work in progress.

  10. Re: loudness-I use my Revolution in my garage with headphones while watching movies/tv. It’s not slient, but it’s far from bothersome for me. It’s like someone is running a vacuum one room over. People in apartments/small rooms/etc. may have a different experience.

    Re: speed via Ant+: Mark, have you tried searching for a speed-only sensor? I paired to my 910XT by searching for a power meter. Power displayed, but speed did not. I searched for a speed sensor (not speed/cadence sensor), and it paired. After doing that, my 910XT gets a speed reading off of the Wattbox. I’m not sure what Jason is experiencing; the Wattbox neither has a display nor transmits cadence data.

  11. This is for those having issues with their Watt Box not showing speed, or showing cadence and power only on their Garmin. This applies only to Garmin devices and I do not know any other information

    As has been discussed on the Lemond Facebook page, it is possible to get three of the four outputs displayed on your Garmin device — Speed, Distance, and power — if you are using a GSC-10 speed/cadence sensor.

    In order to get all three to display you need to go to your bike profile and change your speed/cadence sensor settings. To do this you need to go to menu -> bike settings -> bike profiles -> [bike profile you’re using for your Lemond] -> Ant+ Speed/Cadence -> sensor details -> sensor type.

    Under Sensor Type select “Speed and Cadence”.

    After doing this and a sensor scan, you will pick up the speed sensor output from the Watt Box. This will allow you to get speed, distance, and power readings on your Garmin.

    Unfortunately, you can’t get the cadence sensor from the GSC-10 for some reason, even if you hand enter the Ant+ ID number for the cadence sensor in the sensor settings. Lemond is aware of this and is working to resolve the issue.

    The workaround is to use a cadence-only sensor. If you do that you will be able to add cadence data and thus able to have speed, distance, cadence, and power readings. However, this probably having to remove your GSC-10 sensor. This isn’t convenient if you want to switch between road use where you need/want speed and cadence data from the GSC-10 and using with your Revolution since the GSC-10 is held down with zip ties.

    Solution?? Switching to Bontrager’s cadence sensor and their speed/cadence sensor is an option. They are held down with O-rings / “industrial rubber bands”, and are thus easy to swap out. The downside is having to purchase two new sensors. But it will do the job.

    It’s a bummer, but the Watt Box itself does work very well. Getting all of the data you want is another story.

    Teething issues always suck.

  12. Regarding the speed on Garmin head units.

    My experience is that the GSC-10 is what garmin call a “spd/cad” senor, in that it measures both speed & cadence. On the Garmin 800 series, you can search under the speed / cadence menu for
    -Speed and Cadence

    The GSC-10 is Spd/Cad, and in effect I think that means it sends speed and cadence effectively “on the same channel”, you can’t just pick on or the other data items. I have tried just to get Cadence from the GSC-10, but can’t, it will only pick up if I use the Spd/Cad setting.

    I’m now looking for seperate speed / cadence sensors, as I don’t think the wattbox will do what I want. I’ll get one speed sensor to actually mount on the lemond trainer, one for the bike wheel and the cadence to mount on the pedal. A bit of a shame, as I ordered another GSC-10 to try to get a seperate speed data stream, but I don’t think it can be done. I’m lucky enough to have a few bikes though, so the sensors won’t go to waste.

    Would be delighted to be proved wrong, if anyonce can get a GSC-10 to connect as speed only, of cadence only, please let me know.

  13. You won’t get the GSC-10 to output speed only. The speed reading you need is the one from the Watt Box itself.

    With the GSC-10 attached to your bike and your Garmin device set to “speed and cadence”, you will now be able to pick up the speed and power numbers from the Watt Box and with the speed number the Watt Box will be able to calculate your distance. What you will not get is the cadence, which is for the reasons you noted above.

    Instructions on how to set the Garmin up are in my post above if you have an 800 or 810. I do not know the precise steps for the 500 or 510.

    You will get speed, power, distance, and cadence once you attach a cadence only sensor to your bike. As I said above, for ease of use and convenience I went with the Bontrager sensors since they don’t use zip ties. That way I can switch bike profiles and use the speed/cadence sensor (akin to the GSC-10) when on the road and the cadence only sensor when on the Lemond.

  14. @Just passing through – Thanks for confirming, I’ve ordered bontrager sensors to use going forward, and the GSC-10’s will be fitted to my other bikes.

  15. So I jut installed the Sigma Cadence sensor instead of the Garmin Cadence/Speed sensor. Since I can get speed data from my Garmin 510 via GPS when on the road, I do not need a speed sensor. Works fine now. No need to have a GSC 10 for both a combo and dedicated cadence sensor. The Sigma Cadence sensor is on permanently without having to take it on and off. My Garmin 510 now shows speed, distance, power AND cadence. I am sure the Bontrager Cadence only sensor would work fine. Oh, lastly, the Sigma Cadence sensor can attach both via zip ties as well as rubber bands. I hope that helps!

  16. The GSC-10 can’t be used in cadence only mode, i’ve been using 2x GSC-10 and trainer road to get power from my lemond revolution.

    i wanted to use the speed from one and the cadence from the other as the speed sensor arm can be tilted towards the small magnet on the revolution. I’ve had to live with speed and trainer roads approximation of power.

    The garmin head unit will only see the GSC as speed and cadence so you can have it display cadence with watt box and have no speed or switch to sigma / bontrager cadence sensor. As above no real need for speed data with the GPS, but suppose its back up in the trees etc…

    5 minutes after fitting everything working fine, thanks for launching this after so long. And boig thanks to Merlin Cycles half price offer!

  17. The speed / cadence / distance / power is all determined by what devices you select on your garmin head unit and how you set up your garmin. Not by the wattbox

  18. I have had the LeMond revolution for a couple of years now and it’s been a love-hate relationship. I had a Blackburn Tech mag 6 before the LR. As far as feel…it’s simply amazing and I love it. Noise was an issue in my townhouse but now have detached garage and it’s not anywhere close to an issue…neighbors don’t seem to care either. HOWEVER, I hate have to cob together the speed/cadence sensor so I can use my trainerroad/sufferfest combo. I ride my TT bike (trek SC 7.5) and I can’t use the integrated electronics on it. What I am hoping is that I can with the Watt box, with the bontrager cadence/speed sensor and get power/cadence/speed and not have to go through zip tie craziness every time I want to take it off the trainer.

  19. Here is another issue I have just encountered.
    Installing the watt box, the screws just didn’t grab, either there was no thread to start with on the trainer or the screws are too small.
    Next problem, with the bike on the lemond, and watt box held in place, it actually hits the frame. So even if I could have secured the watt box, I would not have been able to fit my bike.
    Anyone out there experience these issues? If yes, is there a solution?

  20. Erik I received my wattbox today and same problem as you had. Screws were too small so I bodged these with some ptfe tape for now until I come across some screws that will fit. Also my bike frame didn’t fit over the wattbox so I removed the plastic cover so it fits and works fine now. I’m awaiting a bontrager cadence sensor but for now I have power, speed and distance displayed on my garmin 800. Good luck.

  21. Ah so it isn’t just me …. the screws didn’t grab here either… unbelievable for such a robust unit. Also the POWER PILOT gives readings that flicker / blip all over the place… anyone have an answer for that ?


  22. Yeah, screws didn’t fit for me either and my compact frame also hit against the Wattbox. After working with the support guys for a while, eventually I just took off the cover and used zip ties.

    Kinda ghetto, but it works. Been using it that way for 7 months now.


  23. No puedo conectar el garmin 810 con el watt box.
    Es el watt box inicial, ¿ Debo cambiarlo por el nuevo watt box o se puede actualizar el software?

  24. I’ve just picked up my first LeMond Revolution and am just in the process of getting it set-up. It’s an LR 1.0

    At the moment, I use the Polar CS600X for heart-rate, cycling and GPS data – it uses seperate speed and cadence sensors.

    I want to train a little more intelligently this winter and get some power data whilst training indoors on the LR. I can see that my first purchase needs to be the Wattbox to actually have the speed/power data sent somewhere.

    However, the Polar device already has separate speed and cadence sensors. I know that the cadence will be fine to continue to use, but I am wondering if anyone happens to know whether the CS600X will receive the speed and power data from the Wattbox? I already know that the Polar device “can” receive power data as they talk about it receiving power data from the LOOK Keo pedal set, so I am kind of assuming that it’s being sent via the ANT+ standard, but I can’t see anywhere on the Polar website that actually says whether it’s ANT+ or not!

    It would obviously be awesomely helpful if it was… however, if not, I would be extremely appreciative of any other users detailing exactly what kit they are using to gather speed / power data whilst using the LR? If I have to – I’ll get a Garmin somethingorother and use it, but I’d rather avoid having to experiment the hard way!!

    Many thanks


  25. Hi.my trainer is missing hub nut spacer causing the flywheel to wobble. If tighten too much the wheel is not free wheel. Any idea what I can use to replace the spacer? Thanks

  26. My two cents…I’ve had my revolution for two years and have used the WattBox for one year. I have a Suunto Ambit2 and a Bontrager cadence sensor. Using sticky velcro strips I’ve velcro’d a speed sensor to the rear of the Revolution’s arm and aligned it with the magnet embedded in the trainer’s freewheel. Works fine.

  27. I’ve had my Revolution 1.0 since it came out and bought a Watt Box pretty quickly too and think together they make the perfect combination for dedicated trainer work. With an ANT+ cadence sensor I get all the data I need to train and improve. I mostly focus and time and training load so have no need for speed and distance. They broadcast perfectly to my Edge 500 and to my laptop with an ANT+ stick for Trainer Road, or any other online training tool. It is a loud, heavy and a pain to transport but rides better than any other trainer I’ve tried. Like someone else said on here – it pushes you to ride harder.

  28. I am not sure why the focus above is about the speed being an issue… your stationary so who cares.. unless of course your using Zwift or another training tool which requires it.

    I am interested in the power outputs accuracy ? has anyone tested this against other units for data output ? I see DCRAINMAKER has one but there is no test published as yet.

  29. I have been following this thread as I have been trying to get my revolution up and running. I upgraded the 10 speed to 11 speed.

    Prior to that I was using a bont speed sensor nd my joule 3 to pick up speed and cadence etc.

    This year I am picking up nothing from the speed sensor. I assume its the sensor and am not keen to buy another. They should lastmore htan one battery change.

    Lemond have had an out of stock on the wattbox all 2015. They’ve even stopped giving estimates of instock, and ignoring queries (from me at least.) I’d check in once every few months and finally got them to refund my pre-order.

    This is a frustrating issue. I’ll wait until lemond supply the wattbox or announce their bankruptcy. Its a lot more complicated than it shoudl be

  30. Hoping that maybe someone is still monitoring this thread.
    Just picked up a used Wattbox and have it paired to my android Wahoo app (yay!) but I can’t find any information on wheel circumference setting for the Revolution fly wheel. Anyone know?

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