Welcome! first off make sure you know All of the laws regarding open carry.I think you might have to carry your gun in a case in one hand and walk your bike with the other until your out of the school zone. Then when out of the school zone holster it and ride! Don't open carry in Milwaukee county parks unless you want to challenge ordinance 47.05 in it's non compliance with Wisconsin's firearm pre-emption law.
Here is the statute:
(2)Possession of firearm in school
(a) Any individual who knowingly possesses a firearm at a place that the individual knows, or has reasonable cause to believe, is a school
(b) Paragraph (a) does not apply to the possession of a firearm:
1. On private property not part of school grounds;
2. If the individual possessing the firearm is licensed to do so by a political subdivision of the state or bureau of alcohol, tobacco and firearms in which political subdivision the school
3. That is not loaded and is:
a. Encased; or
b. In a locked firearms rack that is on a motor vehicle;
4. By an individual for use in a program approved by a school in the
5. By an individual in accordance with a contract entered into between a school in the
6. By a law enforcement officer or state-certified commission warden acting in his or her official capacity; or
7. That is unloaded and is possessed by an individual while traversing school grounds for the purpose of gaining access to public or private lands open to hunting, if the entry on
8. By a person who is legally hunting in a school forest if the $xhitlist_md=target-id=0-0-0-40925]s. 120.13 (38).
I wish we had an attorny on this site! lol