About 5 curb miles, in 1 hr, is about the fastest you can go. Typically, cities are bid assuming 3 to 4 curb miles per hour.
If you are used to parking lots, at night, then you know that you can start speeding up when you see a clean stretch, right? Not so with street sweeping. While you can move a little faster here and there, you will usually find out, that on HOA's, there's the psychology that residents have, that street sweepers *must* go slow. For example, sometimes my guys would get complaints "your sweeper was flying through here like a bat out of h*ll!". I'd drive over, look at the place, and it would be perfectly clean. So I'd ask the customer, "uh, what's the problem? Maybe he was just on a clean stretch? it got done didn't it?". But to no avail. They'd strain hard to see some missed pebble, or just defiantly say we weren't being conscientious. So you can see how, you will be hard-pressed to go faster than 5 mph, even on clean easy streets, just to appease the public perception that street sweepers are slow gangly beasts
Other factors to consider in the formula are 1) proximety of dump spot, and do they provide that? 2) water source... must you provide your own water? Is there hydrants on site they'll let you use w/o a meter? 3) Is it prevailing wage? 4) Do they want corners blown out, dead-ends, etc...? 5) Is a pass down the curb lines ok, or do they expect the middle done, even if the debri is naturally windrowed to the sides? 6) Is it so thrashed w/debri, that you'll be needing to make more than 1 pass? If so, factor that in..... curb miles practically goes out the window then, or is vastly re-arranged.
Once you've figured out how fast you think you can move per hour, then just multiply it through the expected hourly rate you typically try to get.
Usually though, curb mile type bids don't even apply to HOA's anyhow. They just want a flat rate ("$200 p/sweep, at 1x p/month" or whatever). So you can just drive it in your car, and mentally know "this would take me 1.5 hrs." or whatever. Another way I sometimes do odd-ball 1-time, or on-call type work, is to just bid by the hour, and let the customer be the one to decide when you're done. But if it's going to be a monthly or E/O month type scheduled sweep, then hourly bids won't cut it, in their mind. Good luck.