indoor cycle speed sensor help HELP
 

Okay, so i got myself a cyclops indoor cycle. Kinda like a spin bike, yeah that one. I want to be able to log my miles and keep track of all miles ridden in the year. On the indoor bike, i don't care much for cadence, heart rate, etc. Just distance. I got a Bontrager speed sensor and figure i can mount it on the metal flywheel and use my Garmin 500 to log speed and distance. Will this work right, how accurate will the distance be. I am overly guessing it maybe, read a few things that distance can't be accurate. But if i put in the diameter of the flywheel, shouldn't it be pretty accurate. Thanks

Wireless? Some wireless transmitters will not reach from the rear wheel area to the handlebars. Just sayin'. Distance is meaningless on an indoor bike because resistance doesn't necessarily match reality so the distance isn't real either. Better to know cadence and heart rate. Just my opinion.

Thats what i first thought, but then i thought if i tighten the tensioner the wheel will go slower, if i simulate flat land or downhill, the wheel will go faster. Don't really know how accurate if would even be. Guess i can ride for an hour on it and compare it to my normal MPH on my road bike. If it is way off, guess i can just hook that sensor up to another road bike i have. The sensor i got is Ant+

Cadence/HR/Time would probably give a better indication than distance and speed on the turbo...

By the 'flywheel', is this not a turbo and is a spin bike? I would suggest strongly of not installing a speed sensor on their flywheels. Some of those reach silly high RPMs, and the magnet is designed to mount a spoke, rather than a (I assume flat?) flywheel. If it is a spin bike, their flywheels aren't usually 700c, some are bigger, most are smaller (like a magnetic turbo trainer resistance unit) and spin very, very quickly to give the desired flywheel effect.
Only just read the 'diameter of the flywheel', so I'm assuming it is a spin bike... They aren't made for measuring speeds/distances (unless it's electronic, in which case these read-outs are on displays anyway), they're made to be measured via effort, rather than speed.

If it is a turbo trainer, then the speeds you measure will probably not seem unrealistic, and are comparable against speeds on the same turbo trainer. They aren't accurate by any means though and aren't comparable to outdoor speeds/distances.

I sincerely apologise if I've mis-interpreted your post... But it looks to me as if you're trying to measure the speed of a spin bikes flywheel... Also, apologies on the long post, it's been re-written a couple of times.

I think what you did is talk me out of this whole idea. Yes, i am referring to their spin type bikes. I saw a post somewhere where the magnet was secured with adhesive, but that sucker could still fly out and crack a tv or window. Think i will not do it after all, and just ride for an hour and call it something like 10 mph on my Garmin Manual input. My road bike i get anywhere between 12-18mph depending on riding conditions.

Speed and distance are meaningless on the trainer. You want heart rate, cadence, and power.

I put an old Trek cyclo computer on my Schwinn Spin bike. I just put a rare earth magnet right on the outside of the flywheel and it has never moved. It also has a cadence sensor and gets the job done. I also have an Edge500 and use that to track my HR. I do have enough bits to put a Garmin cadence sensor on the spin bike and with the HR strap, would be nice to have to record some data from the spin bike sessions. Maybe that will be a good Christmas day project.

Good luck!

In theory what you propose is do-able. Assuming you could secure the magnet to the fly wheel then you would want to input the diameter of your wheel (not the flywheel) since the speed/distance calculation is computed using rpm and diameter of your wheel. Considering that mounting something to the flywheel is probably not advised I would think that Cycleops might have a computer or some solution. Have you looked at what they offer?

I did something like this on my wife's spin bike and it worked fine. I JB Welded the magnet to the flywheel so it's not coming off. Works great, you just have to understand that the speed/mileage is only meaningful in a "relative" way (i.e. compared to past workouts on the same spin bike). Cadence (which I also installed) and a HR monitor are definitely more useful for training purposes.

I didn't mean to give a 'scare' factor to the post. The speed would be comparable to other sessions on the same spin bike, and you could 'manufacture' the number you input to the speed sensor to give something you feel is realistic. For example; the first time I got my speed sensor for my Garmin was a GSC-10, I couldn't be bothered to measure my wheel size and I couldn't ride it to calibrate it (weather, time). So I just did a session from 3LC. According to the sensor, I was warming up at 60mph and during 5 minute efforts I was averaging speeds of 150mph. I think you could expect similar recordings for your spin bike (i.e wildly unaccurate speeds, but they're comparable if you use the same spin bike).

Personally, I think you'd be better off measuring HR/Cadence/Time...

It's fine. A garmin speed-cadence sensor is 100% safe and works extremely well when mounted to rear wheel. The magnet won't fly off and even if it did, wont' break anything.

The speed/distance on your trainer won't match real world numbers. It might be close with a good trainer, but it might not be. Just imagine - if the trainer resistance is way too high compared to a real world, you'll have way low distance numbers. And vice versa if it has zero resistance- you'll go 30mph barely breaking a sweat.

That said, I definitely disagree with all those above who say it's useless. Having the distance on your workout can be extremely useful. Total distance covered on steady state efforts gives a pretty decent estimate of total work you've put in, so as long as trainer settings are constant, you're clearly improving if you can go 60,90, 120, etc minutes as you get stronger. As well, trainer speed is a very useful surrogate of power on most trainers. Meaning that you can use your trainer speed as a gauge of how hard you're working at any moment - very useful for things like hard intervals or even long steady state efforts. Again, all the data is relative to prior efforts - if your speed on the interval is getting better over time, you're getting stronger. But you wont' be able to compare to others.

I spent a year and a half without power and using only a speed/cadence sensor for serious indoor training, and it was undoubtedly a key addition to the workouts, being able to track speed on my intervals (worked even better in conjunction with HR). You'd be surprised how with just riding with perceived effort, your power can drop off especially on long rides - with the speed sensor you'll see that dropoff immediately and can even find the point where you have aerobic decoupling (power drops off a lot for stable HR - Friel makes a big deal of this point).

(I'll also anticipate now that some powermeter fan will reply to this post pointing out how useless these metrics are compared to a powermeter. Yes, that's true - I now train with a powermeter, and it does all of the above, better and reproducibly across different users. Still doesn't mean a speed sensor is useless; if i didn't have the means to own a powermeter, the first thing I would get as a serious indoor trainer cyclist would be a speed cadence sensor to get some objective numbers on my training.)

Distance is zero. Totally meaningless to measure distance unless you can somehow calibrate your indoor effort with outdoor effort.

I guess I see knowing the distance/speed thing a bit differently than most. I record every mile i ride on the road in a spreadsheet. When I got a trainer I added a column to my spreadsheet for "Trainer Miles". Personally, I dont really care if it is accurate or not, but I like to have a consistent method of logging what I do no the trainer (or road). Finally, there is no reason that the speed or distance measurement on a bike in a trainer can't be accurate - all you are measuring is the rpm of the wheel and that is as accurate as when you are on the road. It is true, however, that those miles or speed may not correlate to going the same speed/distance on the road due to calibration of the power unit. Regardless, there's no reason not to know or record speed/distance on the trainer - even if you using hr or cadence to set the pace for the workout.

Good riding to all!

Stick the magnet close to the hub so it won't be moving as fast?

http://i.imgur.com/esmE8.gif

:roflmao2:

I read somewhere from the TrainerRoad guys that mounting a sensor to the trainer flywheel does not work. The reason being the smaller diameter flywheel rotates much much faster than where it would be if it where on the wheel and either the Garmin or the speed sensor can't receive or transmit the data at such a high frequency. I couldn't find the mention but that is what I could remember. Someone correct me if I remembered incorrectly.

This is semi-accurate. It has nothing to do with the speed of transmitting the data, it's the performance of the magnetic reed switches they use in the sensors.

However, OP wasn't asking about a road bike mounted on a trainer, he was asking about a spin bike. A spin bike flywheel is on the order of 2 ft diameter and weighs about 45 lbs. A standard cycle computer will work just fine.

My bad. I overlooked that part! Thanks for the letting me know.

Actually, this is correct and my original post was incorrect - sort of. In theory it is possible to mount a sensor on a flywheel of a trainer. But the flywheel will not rotate at the same RPM as the wheel - so that has to be compensated for and a different wheen size must be input into the computer. It all depends on the range of input the computer will accept and the size of the flywheel....probably not likely but I'd have to do some math and look at the specs on a computer.

With a spin bike the driven flywheel is the same (I presume based on the appearance of them) as the rear wheel and most likely will be within the input range on the computer.

Just use teh GPS...