Personally, I think the Tron bike should be excluded from all races. It's a bit too easy* to get and once you have it rarely is there a race profile that it's worth switching to another bike (a race up the Alpe being one of the exceptions). But, whilst it's allowed I'll continue to use it
* By 'easy' i mean it requires you to 'climb' a lot, but actually you don't really need to 'climb' to get the ascent metres. You could just set up workouts and aim for the hills - you climb but without the real effort.