I know there are a lot of variables, but how far can you go on a charge? Lot of cyclists talk about riding about 30 miles on their e-bike, but I regularly ride 50 plus miles, and about a dozen metric centuries a year. (Sometimes these rides are fairly hilly, and my riding partners usually leave me when we hit the hilly sections; hence my interest in an e-bike.) Is it realistic to do this on an e-bike? What should I look for be able to ride a metric? (I am considering a Trek CrossFit+)

If you're pedaling relatively hard on a hilly course and averaging 18-20 mph, most individuals that I've talked to indicate a minimum of 15-20 wh per mile. The Trek battery probably has about 500wh (36V x 15 a-h). You'll have difficulty going 40 miles IMO. Chas58 is a very fit rider; he may chime in with some other numbers for his interesting builds.

A lot depends on what exact bike you have, what motor system you have, what battery capacity you have, your weight, riding style, terrain, etc. Check out Bosch's online distance CALCULATOR for one reference point. Plug in your variables and see what it spits out. I've found it to be pretty accurate.

Also notice the "dual battery" toggle. Some Bosch bikes support dual batteries, which might be just what you need. Or just purchase a second battery for whatever system you end up with.

I have a 30ah pack at 48v, on speed-1 it's good for over 100 miles.

Speed-5 is another matter...

This is like polling a group of drivers and asking them how far they go on a tank of gas. It depends on size of gas tank, speed, weight of vehicle, and other factors right?

For an e-bike, if you tell us how many volts and AH in your battery, plus your speed, it then becomes somewhat predictable, using calculations similar to what 2old gave you.

Here is my data point.
Got a Giant Road E+ recently (did not get the Trek Crossrip+ due to the price difference).
I am 144 pounds and carries a pannier that is about 10-12 pounds. The e bike itself is about 45 pounds.

The motor comes in 4 mode. Off, Eco, Normal, and Turbo. The battery is 500w.

2 weeks ago, did 46 miles with 5000 ft of climb averaging 13.4 miles an hour Did the whole thing in mostly Eco mode except perhaps 10 minutes on Normal mode.
Finished with 30% of battery left and estimated range of 27 miles left.

Last Sunday, did 70 miles with 7500 ft of climb averaging 14.2 miles an hour. Motor was mostly off or in Eco mode on the flat. Motor in Normal mode most of the time during hill climbing (did 30+ miles with 3000 ft climb the day before that and the legs were a bit less fresh). Exhausted the first battery near mile 50. Finished the ride with the second battery at 40%. With a push bike, it would take me like 8 hours to do this. With the e bike, it took a little less than 5 hours - it was a good ride.

What's a "metric?
With an 500Wh battery and 250W motor you can reach 75km at highest support level.
Depending on elevation, temperature, system weight and road surface it can be less. And with lower support it can be up to 160km.
https://www.bosch-ebike.com/en/servi...?setLanguage=1

A 400Wh battery lasts me 70km on relatively flat terrain. A 1000Wh combined (Bosch DualBattery) in Tour mode (note: Tour, not Eco) lasts me about 130km.

Thanks. That link helps a lot. (A metric is a metric century or 100k.)

It depends on how fast you want to go. I have a fairly large 835Wh battery on my Cross Current. On the top assist level (600-700W of continuous assist power) I can go about 30 miles. Figure 30-35Wh per mile to cruise at 28mph. To cruise at 20mph you’d be using about half as much power so you would (theoretically) almost double your range. If you’re willing to ride on the lowest assist level you can massively increase your range. In general you should be very wary of manufacturer claims about range as there is no standard and there is a lot of exaggeration that goes on with marketing claims. I personally like to ride fast on my e-bike so the range numbers quoted for the lowest two assist levels are not relevant to my personal use case.

It depends on a lot of things, but the science is simple and universal. Most of the variables are in the rider, not the bike.

When i say my bike is good for 100 miles, that's constant assistance. I don't see the point in throwing in periods of non-assistance. If i have no assistance half the time, then that becomes 200 miles.

You can calculate your bike's ability with a few specs.

30ah battery - this means 30 amps for an hour.

On my bike, 30a is good for 1,500 watts. That's one hour of cycling at 1,500 watts (steady 40mph). So 40 miles.

Divide that into 5x 300 watt segments, that gives me five hours at 300 watts. Which is good for 20mph. So 100 miles, at 300 watts of assistance.

In my experience on the bike, this all reflects pretty well. Though my highest gear is 2kw at 45 amps, and the batteries can't reach 45 amps well within the hour. So the ampage release capabilities of the battery are to be considered when nearing heavy load.

Also, at 300 watts my legs are assisting a higher percentage of the overall output. Where as at 2kw the motor is doing almost all of the work.

Then there's battery cut-out margin. Not a lot of people know this, but when a lithium battery is flat/empty, it's actually not flat at all. Flattening it would kill it.
I've set mine to cut out at 45 volts. It starts off at 54 volts. If i set it to cut out at 40 volts, obviously this would increase my range. But it's not good for the battery, and would shorten it's life cycle.
Different batteries/systems have different tolerances and protections, so these will affect range also.

So stretching everything, i could claim ''Up to 500 miles'' perfectly legitimately. But it's meaningless. It makes the most sense to say ''30ah 54-45v @ 250w-2,000w'' and you can see what i have at my disposal from that.

This may or not help; today's MTB ride, per my friend's Strava set up, was 12 miles, 3200' of ascent, (about 8 mph average). He @ 150 pounds used 20% of his Bulls (Brose motor) 600 a-h battery. Me @ 180 pounds riding a BBS02 and 52V, 6 a-h battery used 25-30% of the capacity. Theoretically he could travel 50-60 miles, me 30+. We pedaled moderately most of the time and without the motors on flat or downhill areas, but as vigorously as possible on the climbs.