MICHAEL GALLO from Rochester, NH on 6/2/2025 4:01:46 PM:
No difference. Just keep the wheel size under 52MM or 2.0 inch. It can be larger if they don't hang it but that's up to the conductor. You reserve the space as a hang up in the car where you remove your bags. That's why its set to 2 inches. I would never try anything larger because there is no guarantee they will find space if you can't hang the bike. I've done the trail several times and I think 25mm road bike would be uncomfortable with the crushed limestone on the western part. 35 to 50 mm is perfect. So a gravel bike, especially one that favors a tour-like geometry, is perfect. I've used Teravell Gravel Tires, Surly 40mm Extra Terrestrials, and Vitoria Randoneur 38mm and Vittoria Mezcal 2.1. Anything larger on a non- electric bike is overkill.