So I have a Trek 800 that is a bit to small for me but intend to use it anyway. I don't want to wear out my Olmo on the daily commute, but I also want/need a gravel/dirt rider.

My first thought was put a BMX stem/handle bar on it and make it a dirt rider. I think it would work okay if not very well, it is a mountain bike after all.

My second thought was put a riser stem and drop bars on it and make it my daily commuter. It has a rear rack on it so I should be able to put a pannier on it for hauling my laptop and lunch.

I have one cheap, old set of wheels with Maxxis Holy Rollers on them and one mismatched, older but somewhat nicer set of wheels with cheap wide slicks so there is some versatility there. Both rear wheels could take an 8 speed cassette though currently it is set up as a single speed.

I have a Deore Hollowtech crankset installed. Regardless of which way I go I will need pedals, stem and a seat post. If I go the BMX route I will also need handlebars.

What do you all think?

The drop bar commuter sounds like the ticket to me. It would make a nice winter or bad weather bike.

If it's too small in MTB config, it will be way too small as a drop bar commuter. Looks like only a 14 or 15" frame.

FWIW, I ride an 18" Trek MTB, but as a drop MTB, I use a 20"-21" frame.