veloman said:
It seems everyone is converting one to electric.
Everyone. Who. There are hardly any kits out there to do this kind of thing right now. And as one who has looked into it, the whole game is bedeviled by incompatibilities, lack of standards, high prices, availability problems, and lack of choices. Maybe people are coming to ES to figure out how to do it, considering these challenges. So while it may seem like 'everyone's doing it', I would nuance that by saying that few people are doing it, but many people would like to, and are trying to figure out how to now, and this is the place they do it. Right now, it's easy enough to go the lamer route and pop a 135mm rear motor hub on the front of a fatbike. But try to do it right, or better, and you'll run into trouble. A short, incomplete list, even if you can find a motor with a wide-enough axle: most fatbikes come with 32-spoke rims. All hub motors I've seen are 36H. And those fat rims comprise a big part of the cost of your bike. But right off the bat, you're buying yourself a ridiculously expensive 3rd rim, possibly needing to learn how to lace it yourself as a beginner because the pro service manager at the bike shop politely turned the job down because it was too difficult for him to bother with? That's a nice intimidation/bother/learning curve for a beginner who just wants to have a fun ride, not become a higher skill level than a local bike pro (who probably knows zero about ebikes, by the way, and might even be hostile to them, so you're more likely to be on your own). But even if he takes the job, it's gonna be $50 to start with, plus $1.50-$2 per spoke, and can go up with difficulty. So with 36 spokes you're looking at at least $120 for the bike shop to spoke it up for you, plus your ~$100 shipped new 36-spoke rim. So $220 extra on top of your new expensive fatbike--just to pass Go. What are we up to now? ~$380 extra just to get a decent-steering e-fatbike? And that's before your suspension seatpost or other suspension upgrades to make it really nice-riding. Chain clearance issues. Most fatbikes come with crappy tires that need to be upgraded (see above); car tires are literally cheaper. Try sticking a BBS02 mid-drive on there. Won't fit. 100mm bottom bracket. People have been literally grinding down their BB's to make them fit, nevermind what it does to the value of the bike overall, but even if you can do this, you're not guaranteed success. Fabikes that come with BB's different from what was pictured on the web. I can stop there, that's enough; but I could go on. I also think that those who have succeeded, are very proud of theirs and want to show it off (or help people by showing how they did it--not always the same thing), or maybe want to sell it for a big profit. So it may look like there are more out there than there really are. On my local craigslist, I've seen mass commercials for retail e-fatbikes, and I've seen used and new electric bikes for sale, but I have seen not one DIY, or used prefab, e-fatbike, at all. Maybe your experience is different? I'd like to hear if so. Sorry if it's a bit bristly, but it was another comment that seemed flippant, or lacking information to support the perception, but passing off that perception as an observation. But it did get a really interesting, insightful conversation going, so it's cool. I've just spent so much damn time and effort researching this, only to decide to wait, and maybe do something different for now. Every time I overcame an intellectual/planning hurdle, another stumbling block immediately appeared. I'm telling you, it was cosmic. Almost like the Universe was trying to tell me something. At some point, I just started laughing when it would happen, as if on cue. So no. I don't think everyone is building one of these.
Another thought: as hub motors become more powerful, and stators wider, well, typical 135mm rear dropout bike frames are already running out of room. Wider hub motors are already being made, that have difficulty fitting (especially with choice of freewheel and disk), or just don't fit at all. I can see people in the future, desiring a fatbike frame, just for the wider dropout room, even if they choose to ride normal bike tires. Which they could do, with a fatbike frame. They couldn't do the reverse.
dogman said:
I'd known that dirt motorcycles have the same type of setup of course, a bit lighter and narrower front tire. And a smaller diameter rear tire. It would make some sense to me for off road bikes to have fat 24" rear wheels and 29" fronts. But not with today's frames.
That's basically my e-bike wet dream!
I think we have just discovered THE NEXT BIG THING! You realize this is genius, don't you? I'm serious. This could really be the next big movement, after the fat bike sales surge dies down, and novelty wears off. I've never understood why front & back have to be the same diameter, except for economies of scale, and convenience. To ride right up over a curb (a nice luxury), a tall, thick front tire is important; but not as much in the rear. I suspect that 24-inch rear might be the best e-bike tradeoff of torque and handling, though I do not say that from experience. However, I do say this from experience: 20 inches is too small.
I even thought about how to do this
"24/29" thing (
new name?) on an existing frame, maybe levening out the geometry with an adjustable-travel suspension, like Rockshox Bottomless Tokens, but I don't think I'm smart enough with bikes to try to get that creative. Chalo or dogman should, though. Then let Kinesis rip off the design and geometry, and I can buy one at a reasonable price! Ha ha... It makes sense for e-bikes to have shorter rear tires for torque, even as the rest of the bike world is going to taller wheels. Neptronix took it to the extreme with his 20-inch Magic Pie on a Trek, but that was more as an experiment or uni-tasker (for an uphill race). Still, impressive possibilities/implications. And while a 24-inch would lower pedal clearance a bit on an existing frame, a 29 in the front would raise it a little bit at the same time. I'm not a 'geometry' expert, they say it's a no-no, but it is interesting.
And I swear--I've seen some Downhill bikes with a 24-inch rear wheel (and 26 up front)??? Do those exist??
In light of the above observations, let me ask the question, assuming for now identical tire diameters: why is it better to have a
narrow front, and
wide rear? I've seen some web pages of people who "upgraded" their regular mountain bikes with a fat fork (Salsa Enabler or Rockshox Bluto), and for a time considered doing that myself. One page I read, the guy said 'you get most of the benefits of a fatbike with a fat front'. It made sense to me, as to me, steering and front traction are more important than the rear. Sliding your rear wheel isn't as bad as the front. I now realize there can be some steering issues with fat tires, but it's not a given. I've ridden over many a cement curb, and to me it makes sense to have the fat tire in the
front, not rear. Argumentation invited on this! What am I missing or getting right? If you could only run one wide tire (on an
e-bike, which could change the answer): would you want it front or rear, and why?
For me, it got much easier to ride the kind of soil in my area, with a fat rear and narrower front. 
