Tracking spinning on MFP and Fitbit

I'm going spinning tomorrow and I'm going to put my One on my shoe (I would do that with my MOVband) and I'm going to compare it to my heart rate monitor/calorie burn and go from there. I'll let you know what my findings are

After doing a bit of poking around on the internetz, it looks like most people either clip in on the bike shorts at the thigh (they say it stays on pretty well), clip it on their sock, or tie it in to your shoe laces. All those suggestions will supposedly give you a pretty accurate reading.

yeah normally it would clip to your shoe. I have the body media armband and I need to put it on my calf as it is normally on my left arm mid way. I went biking and it didn't register ANYTHING for steps/pedals lol so I was all O_O wth!!, so next time I go out biking I will be doing this, or might just get a HRM to add to my fitness stash

I wear the One all the time and let it do it's thing figuring out calores. However, when doing exercising I wear my HRM and enter that exercise on MFP. FB and MFP will get the calories adjusted so you're not double dipping. Any activity that is not similar to walking or running the FB step count will be off. Though you usually will still get some credit for steps. Just not as many was you might think. Riding a bike is a perfect example of this. Use a HRM and log the activity in MFP. Since your new to the One. Another suggestion... clip it so that when it comes out of the holder (and it will) it falls into your pocket and not on the ground. Many have lost their One after a few months of use. The only logging you should do on the actual Fitbit site (or app) is your sleep. Everything else needs to be done via MFP.

Well, after my 40 minute spin session this morning, I burned 657 calories. However, I didn't wear my One on my shoe like I wanted to (I had it clipped on my sports bra) and I didn't get an accurate reading from wearing it on there, my One said I only made 600-some odd steps, just in the morning, which I know 450-something I already made on my way to the spin room.
I wear the power sport shorts when i spin, so i don't think clipping the One to my shorts would work out, I'll have to try it on my shoe next time. I intend to spin 3 days a week, so I will have PLENTLY of chances to figure this out!
But, most of the time, I'd prefer to go by my HRM than just regular information from MFP to determine caloric burn. I'm going to keep my eye on this board to update/read updates

The problem with the Fitbit and Spinning is that your effort isn't just about how many times you turn the pedals--your output is highly correlated to the amount of resistance you have on the bike. In fact, the more frequently you turn the pedals over in a given class, the less likely you are to have made a significant output in terms of wattage. In other words, the number of times you turn the pedals and the amount of resistance you are in some ways in opposition. And Spinning (and to some extent outdoor biking) has way less to do with your body weight than walking or running because it's not weight bearing. You will never get an accurate reading or estimation of your calories burned using a tool that is intended to measure steps and makes calculations on output based on number of steps x body weight.

As other posters have indicated, your best bet is to wear your HRM and use that to count you calorie expenditure and manually enter it.

(I'm a spinning instructor.)