Flatland, Midwest roadie here…the wife and I did it a couple of years back. Some of the cliffside drop-offs seem disconcerting at first, but you get used to it pretty quickly (at least I did and I’m afraid of heights). Hardest part for us was the climb up a fire road to reach the trail (not used to the thin air); other than that, it’s not very technical or difficult. It was very busy when we were there (lots of hikers and other riders) so be prepared for that.
There are several options for bike rentals if you need one; pick based on location because driving around LT takes FOREVER. We also used the shuttle service via https://flumetrailtahoe.com/shuttle/ and that worked well for us. There’s also an option to extend the trail onto some “unofficial” portion that goes through Federal (I think) land; ask anyone at a bike shop or at the shuttle service and they’ll tell you how to access it. We went that route and ended up lost in some ski area but had a great time bombing down the grassy slopes to get back (which we cleared w/ employees who gave us directions first).
While Flume was awesome for the views, we actually enjoyed Sawtooth and Emigrant more - Sawtooth was slightly more technical (for us - again, we’re not MTBers), but also had amazing views whereas Emigrant had a ton of variation in terms of climbing/descending, forests, meadows, etc. and was just a lot of fun to ride. You should give one or both of those a look if you have the chance.
FWIW, we rented full sus 27.5+ bikes which were helpful for our non-technical capability (pointy rocks and such that we don’t have here in the Midwest).