https://wbs.ae/bikes/rental-bikes.php

There is a Trek shop at the beginning of Al Qudra, but the bikes looked pretty poorly maintained when I went there.

You can also join the Tri Dubai facebook group and asked the locals (mostly ex-pats) for recommendations. They're a sociable and friendly bunch.

I didn't see the need for a pool when I went there - the sea is awesome and there shouldn't be any jellies until March or so.