Why would you want to limit your users to 80 kbps on an 11 or 54Mbps radio interface?
Remember that radio is a shared medium. If you limit your bandwidth to 80k, that 80k is shared among all users on the access point.... with contention and overhead reducing that bandwidth even further.
I can't think of any wireless application where it would be useful to have users connecting at less than the maximum possible speed. Even if your upstream link is a 56k dialup, you gain nothing and lose performance by throttling down the radio.
The slowest speed setting supported under 802.11b is 1.0 Mbps. If you wanted to throttle it back even further you might be able to do something with QOS commands.
Thanks for posting. I have a separate SSID for guest users, I'm trying to limit the maximum upload/download speed for all the users in that SSID. I don't want to lower the speed setting on the interface to 1.0 Mbps. I was hoping for a command that caps the speed
You can't usefully cap the speed for just one ssid or just one set of users. A radio interface only communicates with one user at a time (no matter how many SSIDs you have), so if you cap speed on any single conversation you're slowing down the network for everybody associated to that access point.