69chevy

I have a spin bike that I'd like to continue to use as my indoor trainer.

I also want to be able to use the Zwift app (and others) and have been on the fence about buying a power meter.

For this to work, I need to broadcast the spin bikes speed, cadence and power over bluetooth or ANT.

I think the most cost effective way to do this is to add speed/cadence to the spin bike (not hard since it already has wheel magnet) and buy a power meter I can use on both the stationary bike and my road bike.

The easiest choice would be pedals, but I like the cost of a Stages unit better. I could make or have made an adapter that allows bolting a hollowtech arm to my square tapered BB spin bike so I could use a Stages meter on my road bike and put it on the spin bike for indoor training.

I have thought about how to do this and my first idea is to find a wrecked hollowtech axle and cut the splined end off. I could then find a cheap square tapered crank and machine the square tapered female end to fit inside the hollowtech axle.

This would require a little welding by a good welder (plus the alloys would need to be compatible), but this the easiest/cheapest option I can think of. The end product would basically be a little splined piece I could bolt to the square BB and then slide a Stages arm over it and tighten it down.

Other than this idea, what else could I do to use a Stages meter that would fit both bikes? Is there an option I have never heard of?

I also thought about getting a 3D printing whiz to print a part like I describe, but that would be pricy, and the plastic likely wouldn't hold up very well. I also thought about machining an adapter, but again, the price probably wouldn't be worth it.

I don't want to sell the spin bike and buy a smart trainer because I would still want a power meter for my road bike. I also don't want to sell the spin bike and use an indoor trainer on my road bike since I already have this very nice spin bike and selling it would mean a big loss.

Ideas?

WalksOn2Wheels

I would think it would be a lot easier to just get a stages arm and then a cheap hollowtech crankset on the spin bike. I got a 105 10 speed crank for like 68 bucks online not too long ago. You might even be able to find just the drive side crank arm and maybe bolt your old rings to it if the BCD was the same. That plus a bottom bracket sounds like a much, much easier job than sourcing out bits and pieces, finding a welder who can actually weld it on STRAIGHT, plus you would have to dismantle it to take it to the welder anyhow...

K.Katso

Two options:

The Favero bePRO Power Meter In-Depth Review | DC Rainmaker

PowerTap P1 Power Meter Pedals In-Depth Review | DC Rainmaker

I have the PowerTap pedals and they're pretty nice. The Faveros are cheaper though, closer to the cost of a Stages.

f4rrest

Plastic adapter wouldn't withstand the torque, axially or perpendicular to the rotation axis.

Unless of course it's Delrin with Loctite 609. Lol.

himespau 

Wow, I hadn't heard of the Faveros before. That's almost getting into the range where they're competitive with building up a wheelset from a good used powertap hub.

69chevy

Swapping the full crank on the spin bike wouldn't work. It belt drives a 40lb flywheel.

I wasn't very clear on the BB setup. It has a square tapered BB like an older road bike. I just wanted to pull the non drive side arm off of the BB and bolt a stages arm on.

I don't have to pull it apart to do it, I just need a way to bolt a hollowtech arm to a square tapered BB.

This is a rough (paint) sketch of the adapter I am thinking about how to build. I would bolt it to the square tapered BB and then slide on the Hollowtech arm and tighten.

Like you mentioned, it will need to be precicely welded (if I try that way) and it will also need to be carefully aligned, since the shimano arm only fits on one way.

69chevy

I'd never heard of them either.

One more reason I really like this forum.

I also discovered this as I search for ideas. Pretty interesting.

PRECISION - 4iiii Innovations

69chevy

I'm guessing it would break or strip etc.. The only reason it crossed my mind is because it would be relatively small in diameter and pretty thick.

I'm not even gonna try it. Unless I find that Loctite 609 will keep it from creaking... lol

f4rrest

Maybe you could create a mold from the existing parts and cast something in low melting point metal or glass filled epoxy.

69chevy

That is a very good idea. There is a cast iron place very near by.

I may price the part there.