Bike Shorts or Trisuit
Well...since you're prepping for a full tri later, I'd probably go with the tri shorts and jersey since you've been training with it as well. If you hadn't I'd say go with the bike shorts.
That being said, I'm a big advocate of racing in what makes you comfortable...the race intensity makes you uncomforable enough on its own, no need to increase that with clothes you don't feel comfortable racing in
I would go with the tri shorts as they do have a different feel and you need to get yourself a bit adjusted. If the goal is to use this event for a full distance, may as well work out how to get comfy in a skinny chamois. Maybe dump a water bottle down there before to make it more realistic too..
Good luck!
I'm going to go the other way. I think when you are racing, you wear what is most appropriate for that event. What wasn't clear from the original post was the definition of "practice race." Do your teammates view this race the same way? Are you trying to be competitive? I raced the bike leg of a team event last year & we won by 8 seconds. Would I have been 8 seconds slower in my tri shorts? Hard to say; I certainly would have been less comfortable & possibly slower as a result. Had we taken 2nd by a few seconds (with me wearing my tri shorts for "practice"), I would have questioned my decision not to wear cycling gear.
If you are already alternating gear on your rides, it probably isn't that big a deal to you what you wear. I would wear whatever you feel more comfortable in, and whatever is going to make you go faster.





So I'm doing just a bike leg of a tri next week as I prep for my first tri in Nov. This is more of a practice race for me.
My clothing options are Trisuit, Trishorts and cycling jersey, or cycling shorts and jersey. Since it's only the bike part I'm doing, the shorts would be more comfortable, but there is that theory of wear what your going to for your actual race. At the moment when I do my rides, I alternate between the bike shorts and the tri shorts, depending on laundry schedule.
What do you think?