Good deal. Since the bike you bought was used, we cannot use the lemon law to get the original bike back.
The Wisconsin Consumer Act grants Wisconsin citizens the right to cancel certain consumer transactions within three business days. Consumer transactions are those purchases by individuals that are for personal, family or household purposes.
This provision applies to transactions valued in excess of $25.00 where the transaction was initiated by face-to-face solicitation away from the merchant’s regular place of business, or where the transaction is directed to the particular customer via conventional mail, electronic mail, or telephone solicitation. The right to cancel law covers transactions at fairs and trade shows as well.
So, if your purchase fits all of the categories listed above, since you notified them the next day, you do have the ability to cancel this transaction under Wisconsin's buyer's remorse law.
If you simply went to the dealership and traded, however, this law does not cover you and there is nothing you can do short of trading your new bike for your old bike, less any financial hit you will take in the process.
Let me know if you have any other questions and please rate my answer positively (Three or More stars) on the ratings bar on your end.
Thank you and best wishes!