The excellent SeaCity museum in Southampton, England has a lot on the Titanic. Apparently, in the exercise suite, there were two fixed bicycles... and as you pedalled one or the other, a "hand" on a clock, one for each bike, went around a dial.
A fun bit of competition for two cyclists? A race? Would be easy enough to re-create with an Arduino!
If anyone makes something like this, I'd be interested to hear about it, and in giving it "publicity" at...
(Attachment is merely a photo of a reconstruction of the gym's set-up.)
Of course this can be done with an Arduino,too. You need encoders to measure the speed (rpm) of each cycle, and make the two hands turn accordingly. You'll have to find a way to move the two hands independently, what requires some mechanical skills.
".. find way to move hands...."... well, yes, if you decided to copy as closely as possible. But alternative displays could give as much fun, more easily! For a large one, the HobbyElectronics serial -to-VGA module would be a quick, easy route. It could GRAPH progress against time! Who is winning, but also, who was fast, when?!
$30 (+p&p) perhaps a bit steep for a mere bit of fun... or THIS project a good way to slip the purchase past the wife?
MUCH cheaper "who is winning?" displays are of course possible. A four digit 7 seg LED? (Left two digits, left rider's "score", right two, right players? (again, serially run...
