As laid down by Peukert's Law, the ability of a battery to deliver all it's charge content depends on the discharge rate, the higher the discharge, the lower the amount that can be used. SLA batteries suffer quite severely from this, so in a high discharge application like an e-bike motor, as little as under 60% of the nominal Ah can be used to drive the bike. Lithium batteries are not so severely affected but can still suffer.
Some while ago A to B magazine tested an e-bike with a lithium 36 volt 10 Ah nominal battery at different rates. Used gently they were able to draw the whole 10 Ah, but at the other extreme of full throttle all the time, they were only able to draw a little over 7 Ah. That was an early lithium battery however, todays are rather better.
N.B. Crossed with Trex's post while typing.
.