OT: dense mouldable material for a cycle trainer flywheel.

[Andy Burns]

1/2 a unit of electricity for every hour you can get a fat bloke on a gym bike, brings a new meaning to spinning reserve ...

[T i m]

Yet?

Could be a nice sales hook to get people in though? ;-)

Cheers, T i m

[T i m]

Hehe.

20 'fat blokes' ... at even 100W/h and that's all the lights covered?

Cheers, T i m

[Thomas Prufer]

It may be easier to install a higher high gear (that's usually changing a single ring in the cassette), and maybe switch to a heavier tire, than to fabricate a balanced flywheel...

Thomas Prufer

[Neal]

Already pretty high on the ratio (52 to 12).

However adding balanced weights to the *wheel* may be significantly beneficial. Roughly 7 times more angular inertia tan weight on the flywheel.

Obviously, the complication is mounting and removal. But if I consider setting up a semi-permanent (existing) basic bike with a smooth wheel, and a suitable range of gears, it should suit the whole family.

I can then attach weighting to the rim of the wheel, giving a massive flywheel effect

Thanks

Neal

[newshound]

I was going to say concrete too. If, like me, you have a big box of old nuts and bolts that might come in handy some day, you could use them as part of the "aggregate".

[Rob Morley]

Fill the tyre with water. :-)

[Thomas Prufer]

Changing that to 52 to 11 is not whole lot -- but easy and cheap. The smallest gear is easily replaceable...

but the flywheel runs much faster, and that transforms the inertia seen at the input of the gearing.

Look at the tire sealant goop -- that goes in the tube, is heavy, and belongs there, i.e. wont come off, won't damage the rubber.

And/or use "motorcycle spoke weights".

Thomas Prufer

[Alan Braggins]

Larger chainrings than 52 exist, I have a 60 on my (small wheeled) folder. Your chainstays probably won't allow that, but 53 to 11 might be possible. Capreo hub will let you go down to a 9 tooth rear, though that also has downsides:

You could add a Schlumpf speed drive, but that's not cheap, and not very easy.

[Alan Braggins]

It's not what the OP asked for, but it's another approach that might solve his actual problem, increasing the rotational inertia of the system as a whole. He'd have to change wheels whenever he wanted to take the bike on and off the trainer, but many people do that anyway.

[T i m]

If you had access to someone with a metalworking lathe ... is the flywheel 'just' a flywheel?

e.g. Could you replace it with a bigger / heavier one?

Is the shaft though the flywheel plain or does it have flats or some such?

I wonder if you could get a spare flywheel and turn it down slightly to make a 'hub', allowing the addition of optional / additional flywheel 'rims'? Could you increase the diameter by much (and if so by how much)?

I'm guessing the tyre runs in the bit between the flywheel and load?

Cheers, T i m