asalt

Hi I was wondering if anyone has any recommendations for a relatively inexpensive e-bike with a very small internal (somewhere) battery and motor. Something like the ones they supposedly used to cheat in bike races. Basically just looking for help on hills but not on flat areas. A bike with a boost.

Leisesturm

What's the joke ... you can have it light or you can have it cheap but you can't have it light AND cheap. Those cheat bikes with the stealth motors cost the moon and nearby planets. You might be served by a 250W motor and battery kit. Built up e-bike will be $$$.

2old

Last time I looked the Vivax assist (four pounds total AIR) was $2,000 - $3000. There are some friction drives that are relatively light and fairly inexpensive. Perhaps the owners will respond.

linberl

These are the cheapest commercial friction drives I've ever seen. Really basic, no bells and whistles, but seems like they would do the job
for the OP. My friction drive (OneMotor) is not inexpensive at all so doesn't meet OP needs (although I highly recommend it, I love mine). But the PEdrives look like simple versions, on/off, easy to repair as well.
Products Archive - Pe-Drives

Pop N Wood

Batteries are the killer of both light weight and low cost. Anything light and cheap will also be low power. Hills require power, hence larger battery, hence more weight and expense.

sloppy12

Define light and inexpensive?

under 30lbs you are probably in the 2 to 4k range.

Better question is why are you worried about weight?

linberl

Maybe OP has to take it up stairs? I do...so adding a 4.5lb OneMotor to my bikes was the perfect solution for me. Made my bike less than 24lbs motorized, and something I can carry up stairs to transit (post-covid and pre-covid) and up to my son's 3d floor walkup, etc. Also, lighter bikes don't require as much power to go fast =).

linberl

Anything light and cheap will also be low power - disagree. Anything cheap,yes. But you can get light and power if you pay for it. My OneMotor goes 28mph (not that I would go that fast, I'm totally a chicken) and climbs hills like a beast - 4.5lbs total so it is definitely light, but it wasn't cheap, lol. Or atleast not cheap by my standards, ymmv. It also depends on how you intend to use the bike - power on all the time requires more battery, but some of us use it intermittently as a boost to human power just for hills and high wind, and smaller batteries can work just fine in those instances. My battery is tiny (110w) but I can easily get 20 miles out of it using lowest assist, pausing on flats, and using it on higher power on hills. OP sounds like usage will be more like that, rather than on all the time giving steady power, and that's a reason to keep it light, so it rides like normal when not juiced.

2old

linberl, Amen, some of us like to pedal.

Pop N Wood

Don't think I explained my thinking very clearly. Battery technology is the limiting factor. Current batteries only have a certain energy density. Drawing significant power for any length of time requires stored energy, more stored energy = bigger battery = more weight + more money.

Doesn't matter how much you pay for it or how much you like to pedal.

ARider2

asalt, if you tell us your approximate budget as well as a weight range you are seeking we can give you some suggestions. Just as important is knowing your intended use for the bike and estimate for how often you will use it and how far will you go.

chas58

Very true, although its changing relatively fast.
5 years ago, I bought a 36v10ah 10lb battery for about $300. Now I can buy the same capacity for 1/3 the weight, and less than 1/2 the price.
Give it another 5 years and batteries will be 2x dense, 60% of cost.

I'm enjoying the evolution.

linberl

That's true but for users who are only drawing significant power for short lengths of time (quick hill climbs) AND riding bikes under 20lbs, the size of battery needed can be smaller. You definitely need a bigger battery to haul a 40lb bike + e-system and a larger rider up a hill, and you need power to move that heavy bike all the time as well. No fun turning it off and riding, unlike with a lightweight system like the OP wants.

ephemere

One of the best deals I've seen on an e-bike was someone who bought a 2020 BMC Alpenchallenge AMP City One new for $2100. Relatively light (17 kg), solid mid-drive motor (Shimano E6100), big battery (504 Wh), and a generally good-riding bike with the motor/battery weight centered. I spent more and got the Cross LTD myself, which is lighter (15.1 kg) and has an even stronger motor (E8000), and I ride for long stretches unassisted. I don't know if this satisfies your definition of light or inexpensive.

Another bike that comes to mind, especially if you are really on a budget, is Propella. They have a 15.9 kg single-speed for $1000 and a 16.8 kg 7-speed for $1300.

Finally, you might want to look at the Motobecane bikes at the bottom of the page on bikesdirect. There are some flat-bar and drop-bar mid-drive bikes in the 15-16 kg range at $2-3k.

(I tried to add links throughout, but I'm not allowed to post links.)

ephemere

There's also the Luna Stealth for $1750, a little heavier than the above but still light by e-bike standards, and definitely stealthier than the others I mentioned, although probably not geared sufficiently with a 3-sp IGH.

gsa103

Interesting, Vivax went bankrupt during Covid, so you may be able to get one of those at a serious discount.
Batteries aren't that heavy as long as you're willing to accept limited range. A minimal 36V pack (10s1p) with decent Li-ions will do >300W all-day long, if you spec high-current batteries you can easily get 500W sustained. A Luna Wolf Pup pack weighs <4 lbs for a 200Wh pack that can do 1500+ W.
A simple 250W rear hub motor and small pack would be around 10 lbs added to a bike. With some care you could easily get a bike under 30lbs.

The trick is inexpensive. Typically, price is a major driver so most manufacturers cut corners on everything else, so even though the battery and motor only add 10lbs, it's piled on a 30lb bike.

asalt

Fair point. Okay, let's just say "least expensive".

asalt

Thanks, looking at that. That is the kind of thing I was thinking of. Not too inexpensive hah but looks great.

asalt

Exactly, and thanks for the suggestion!

asalt

Well having seen the replies. I suppose I am looking at adding a light (5 pounds or less?) motor to a nice road or gravel bike. Budget...as little as possible haha. Eventually I might spend up to a couple of thousand on a motor I suppose. I mean I'm looking for the low end of the range, just to get an idea of what there is.
And definitely usage is to add a power boost for hills or maybe sometimes for long distances, without adding too much to make the bike usable as a normal ride for exercise.

Thanks.

asalt

This is exactly what I am thinking of. Small battery, light system, limited capacity and ability to ride it like a normal bike. Thanks.

linberl

So the OneMotor system I got may be outside your budget ( or not) but it's awesome. With the small battery and the kind of use we are talking about, I get 20 miles range and it's 130wh. The whole system, all of it, is 4.5 lbs. Everything is wireless and it pops on and off my bike in less than 30 seconds. It also goes on my second bike; I purchased a second mount. So the cost makes sense if you have more than one bike you want to motorize.
However, if it is out of your budget, you might want to look at the PEdrives I posted above. They are basically small friction drives, super light weight, and will give you a boost when you need it but let you ride like normal otherwise. The thing about hub motors is that there's always a tiny bit of drag when you aren't using them and they also weigh more. So for a traditional riding experience, I personally think friction drives are great. Yeah, you might burn through a extra tire each year but they aren't that expensive. I have had my OneMotor for about a year and half now, and I just replaced my tire so just slightly more wear than normal. Now the OneMotor has fancy software and such so it auto adjusts during wet weather - the PEdrives don't so if you live where it is really rainy they may not be a solution for you (or any friction drive that doesn't have the ability to auto adjust the tension).
If that's the case, then your best bet is probably the smallest hub system you can find, there are some Bafangs that are around 6 lbs for the hub motor I believe, and just use the tiniest battery.

Sham69

i also look for a good inexpensive and lightweight e bikes, something with free or inexpensive shipping across the world

any good options ?

Doc_Wui

There are plenty of inexpensive ebikes thses days, but they're not light. Think around 50 pounds.

I've converted a number of existing bikes to electric. A small 250W-350W motor is under 5 pounds. A small battery is about 4 pounds. Electrics add 2 pounds. If you start with a light bike, you can finish with an additional 11 pounds. For cost, you will pay about $600 for the drive train, although some of us can get by with lower cost batteries. That's about where inexpensive ebikes ate in price.

My lightest full size bike is a 700cc Diamondback Mara Vista. It's about 45 pounds with a 250W 36V rear motor. I have some 20" folders that are 36-38 pounds and a 20" mini vello that's maybe 33 pounds. Might get another one.

2old

I built a sub 35 pound e-MTB with a 10 (or so) pound BBS02 and 3.5 pound Luna 52V, 6ah battery, GT Zaskar frame, Ritchie carbon fork and some pretty blingy parts that I had from years of weight weenie exercises on MTB bikes. Still had room to drop a couple of pounds and another two or so with a Revel Propulsion system which was on another sub 35 pound MTB. Been awaiting a four pound mid-drive DIY motor so a sub-30 is achievable. Picture of the second one below.