Why are the e-bike sold only with heavy inefficient fat tires?
Nothing more wrong. You must have looked at budget e-bikes popular among a
certain category of mostly North American e-bike riders. While, there are all imaginable classes of e-bikes out in the market:
- Super-lightweight e-bikes (road, MTB, commuter). For instance, a high end model of Specialized Creo SL road e-bike might even weigh as little as 26.9 lb
- Road e-bikes on narrow, slick tyres
- Gravel e-bikes with somewhat thicker (but still narrow) tyres
- Hybrid e-bikes (all-rounders) with, say, 1.5" tyres
- Commuter e-bikes with 1.75-2.4" tyres
- e-MTB on tyres ranging from 2.2-3". By no means it is called "fat tyre". These are "off-road tyre" e-bikes, often with full suspension.
I'm sure I managed to miss some more categories. If we put the super-lightweight e-bikes aside, a typical e-bike of the categories I listed above would be 46 through 53 (most typical figure for a mid-drive motor e-bike) to 59 lbs. Don't, however, expect paying $2000 for any of them.
So, it is your choice to select e-bike of a category that fits your needs, with the appropriate tyre size for the purpose. Regarding the weight, the motor easily offsets the bike weight, even at low pedalling assistance. Only in case you need to
carry your e-bike, you might want the super-lightweight variety.
You asked why e-bikes are so heavy. If we take a typical budget Chinese made, stamped, fat tyre e-bike with a hub motor, the hub motor is very heavy. Additionally, owners of such e-bikes love having extremely powerful motor & the throttle (because it is hard for them to start the ride without massive motor assistance). That calls for a very heavy battery. For typical higher quality mid-drive motor e-bike, I might quote the figures for my Specialized Vado 5.0 e-bike (the Euro Speed version):
- Battery weight: 6.6 lbs
- Motor weight: 8.6 lbs
- Total e-bike weight: 53 lbs
- Net bike weight: 37.8 lbs.
Don't tell me a regular traditional commuter bike weighs less than 37 lbs
(Additionally, e-bike must be sturdier than the trad bike because it needs to be strongly built to be able to carry not only the rider but also the motor and the battery).