In the short term, that may be accurate. I think for most guys, having larger equipment is something they get used to. I've spoken to a few guys who have been cleared to go back to full activity post-phallo, and they're back to playing sports and working out like they used to. I'm sure positioning and supporting things is much, much more important now but I think that's about it. Once everything is healed and you're accustomed to it being there, I don't think it would impede your ability to ride a bike or workout.
If anything, what I hear guys have the greatest issue with is the vaginectomy site and general soreness in that region throughout healing. So that would be true for either procedure, if you plan on having a vaginectomy. When I sat down and did my initial list to figure things out, it was something like this:
Need
- Vaginectomy
- Urethral lengthening
- Scrotoplasty
Want
- Testicular Implants
- Concealable donor site (if phallo)
Don't Care
- Size
- Erectile Device (if phallo)
The only things I really care about are getting rid of what's currently there, being able to pee standing up, and having a male looking setup. Size is a non-issue for me. I'm not 100% sure I'll end up getting any implants (testicular or erectile), as I've read a lot of folks having issues with those. I wanted a concealable donor site, but I'm not getting one.
My advice would be to make a list like this, refine it over time, and then have a consultation with a surgeon who performs both procedures. Let them take a look at you and tell you what your body is best suited for that meets everything in your "need" list. If you have your heart set on a particular procedure by that point and they say it's not the best fit for you, ask what you would need to do to make it ideal. There are also some bottom surgery support groups on Facebook and Yahoo groups where guys discuss these procedures and their experiences, so you may be able to ask people directly about their ability to be active post-op.