To determine which model you own, locate the gear selection indicator on the handlebars near the right grip.
Compare your gear indicator with the photos. If the gear indicator shows a 1, 2 and 3, then you have a 3C model. If the gear indicator shows a 1, 6 and 11, then you have an 11R model. If the gear indicator shows a 1, 4 and 8, then you have either an 8C or 8S model.
To determine if you have an 8C or an 8S model, look at the steering column. If the steering column folds, then you have an 8S model, if not you have the 8C.
Finding Your Serial Number
Your serial number is an 8-digit number located under the bike on the round tube between the rear wheel and the kickstand.
The Arc serial number is located on the top of the frame towards the rear wheel by the chain keeper.