started e-bike project, made mistakes, now a lil' lost

So I jumped right into my e-bike conversion project with no real research, no bike and no real biking experience (I last road a bike when I was 10) - I love to tinker and have a couple hundred 18650 li-on batteries so that's all I needed to get started right away LOL. Ordered a 48V 1500W 700c rear wheel drive kit with 7 speed freewheel (eBikeling) off eBay. I picked up a 2005 Fuji Sagres Forza Series 8 speed aluminum hybrid bike (with 700x25c tires) off Craigslist, but immediately felt it wasn't beefy enough (frame, tires) for the project. Then I picked up a 2011-ish Specialized/Globe Vienna 7 speed aluminum hybrid bike (with 700x35c tires) off Craigslist and while beefier than the Sagres it still didn't seem beefy enough. Then I finally sat down and spent a lil' more time researching and discovered the discussions recommending using mountain bikes even cheap models from Walmart/department stores, going with steel frames or at least steel dropouts, front suspension, disc brakes, wider tires, 29ers are the same size as 700c, etc. Then I figured to save this project I'd just get a 29er mountain bike with at least decent front suspension, disc brakes and 7 speeds used off of Craigslist/OfferUp/Letgo or new and cheap from Walmart and upgrade components later. Does this get me back on track or should I look in another direction?

P.S. - I started this project because my car has become sort of unreliable (and I barely drive it anyway) so this e-bike would be an alternate mode of transportation for getting to my clients (all within 10 miles of me) and running errands. I'll mainly be on the road/streets, commuting essentially. I'm in Seattle, WA so there's steep hills. I also hope to tow my toddlers around in their trailer to the park and around the neighborhood.

What specifically doesn't seem beefy enough about the bikes you already have? (You mention "frame, tires" but don't specify what about them isn't beefy enough for your purposes.) Knowing what's not good enough and why may help us help you pick out something that *is*.

Not having either of your existing bikes to look at (or pics of them attached to your post), I don't see anything wrong with using either one to convert, as long as you use properly-mounted torque arms on both sides of the hubmotor axle.



Something to note about wheel size:

--The larger diameter the wheel (and the fatter the tire), the better the ride quality.

--the larger diameter the wheel, the more speed (and less torque) you get out of the same drive system to it.

With a hubmotor you can't really change that without changing the motor itself (and/or the voltage and current capability of the system).

With a middrive you can simply change the gearing to change that.



Some notes about battery placement:

Inside the triangle area is best, if there's space.

Batteries on rear racks will cause "tail wag" (affecting handling) and eventually (sometimes quickly) break the rack, especially with bumpy roads or curb-hopping, etc.


Batteries:

there's lots of threads about building packs from 18650 cells; I'd recommend reading up on as many as you can stomach before you build anything. Including the one or two about how *not* to do it.

Keep in mind not all cells are the same; some are high capacity, some are high current, rarely are they both, more often they are neither. :/

Dunno the provenance of the cells you have, but keep in mind there's lots of recycled garbage out there, so you might want to test every cell before buidlng a pack from them, if you're not absolutely sure they're new and genuine.


Depending on speed and how bad the hills are, you might need 25-40wh/mile, so a "52v" (14s) pack might need to be around 20Ah (worst case, including extra for detours / headwinds / pack aging) to do a 20-mile round-trip.

If the cells are average, not meant for high current, you might need a pack almost that big anyway, to sustain the currents a 1500w system will need (probably at least 30A peaks, maybe more, and on steep hills it may have to sustain that constantly), without putting a strain on them.

Since you already ordered a hub laced onto a 700c wheel . ( Have they sent it yet ? )
Then yes buy a 29er mountain bike, since you have hills and amberwolf said you need a large battery then you will need the space inside of the main triangle for such a large pack so get a hard tail 29 er, and a Thudbuster LT Suspension Seatpost .

How tall are you ? a 29 er frame has less standover height than what you are probably used to , so size accordingly best to test out a few sizes first.

I have looked into walmart bikes ( full suspension ones ) and they need too much money dumped into them to bring them up to a good enough component and brake quality in order to deal with the higher speeds you will ride on a e-bike.

Ok, heres what I think. If you find those bikes not beefy enough, just how beefy are you? Overload the frame enough on some bikes, and you will start to actually see the frame flex as you ride, side to side, as you pedal.

That generally takes over 250 pounds btw. Otherwise, I would think that your bikes and tires are plenty beefy, and your problem is more your perception of the tires, rather than an actual problem.


If you do have a personal weight over 350 pounds, even mtbs might feel a bit petite for your weight, and you would need to have a much stouter frame, such as the better beach cruisers or cargo bikes, which are often a 26" wheel. You could get your wheel rebuilt to 26", or sell off your kit and try again with 26".


If you weigh under 250, I really think you have no big problem, just go with the bigger tire bike you have, and keep riding carefully till you adjust to the tires, and learn how to ride if not more safe, at least less worried. You just need more road time to get fully used to bikes, and ride a bit on the slow side till you adjust better.

LOL! I guess I'm beefy (6' 3", 245 lbs), but when I said beefy I'm referring to the frame being strong and safe enough for faster speeds than it was originally built for. Most of stock/ready made e-bikes I see in the local stores have thicker frames and wider tires and I understand now, from better research, I should mimic that aesthetic in my build for reliability and safety.

Yes, the e-bike kit has arrived (it has been sitting in my home lab for over 2 weeks now).

Here's photos of the bikes I got so far (though I'm willing to sacrifice some bike weight and lose some comfort/riding uprightness for a safer, more reliable donor frame):


2005 Fuji Sagres, Forza Series with 700x25c tires (not my actual bike, found similar on web)

View attachment 1

201? Specialized/Globe Vienna with 700x35c (stock photo, mine doesn't have crank/chain guard, that seat, those lights, fenders nor kickstand)

Cool project, sounds like a good plan! What is width of the rim? 29er and 700c are the same diameter, but road rims are a lot narrower than a 29” rim. “Hybrid” rims will usually work with a 29er tire.

Do not buy a Walmart bike! To replace all the garbage components would cost more than a decent bike anyway. I vote 29er mtb if that is wheel you have, or a hybrid (like that Fuji).

81forest said:

Cool project, sounds like a good plan! What is width of the rim? 29er and 700c are the same diameter, but road rims are a lot narrower than a 29” rim. “Hybrid” rims will usually work with a 29er tire.

Do not buy a Walmart bike! To replace all the garbage components would cost more than a decent bike anyway. I vote 29er mtb if that is wheel you have, or a hybrid (like that Fuji).

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Yes, they're both 700c wheels, though that Fuji has a 700x25c wheel which I assume would be too narrow for a 29er tire.

I don't think I have a choice, I have to go with a cheap Walmart/Amazon/Sears/Target 29er MTB, for now, to keep the project rolling and it'll likely be an undersized frame at 19". It is impossible to find an XL+/21"+ frame 29er MTB or even a 700c hybrid on steroids (front suspension, disc brakes and capable of wider tires) - even L frame appropriately equipped 29ers are few and far between (either new or used on Craigslist/OfferUp/Letgo).

What about this one? Looks to be a hybrid, but hard to be sure: https://seattle.craigslist.org/see/bik/d/bontrager-privateer-shx/6622454125.html

Any “suspension” on a department store bike will be worse than no suspension at all in my opinion. After working at a bike shop for a few years, I am convinced that the department store bikes are barely even safe to ride, and they’re not made to last more than a year. Especially with the added speed and load of a motor/battery. Don’t do it!

You want simple DIY advice?

Great, here's the thread in a nutshell: “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

I like the Vienna frame. But, These bikes don't have front susp. and disc brakes. Nice bikes but no " goodies" I use an old Rincon - no disc and an older FSR dual susp and front disc. And I have 2.95 x 26 on one and 24 front 20 inch rear on the FSR ... It rides like a caddy to me. lol Maybe and see how wide tires those frames fit. mt bike frame would be better imho.. Maybe sell one or both and get a decent hardtail mt bike

flat tire said:

You want simple DIY advice?

Great, here's the thread in a nutshell: “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

Click to expand...

Really? What I got from it is the problems you encounter when you have a lack of focus and don't plan. Hopefully some of the folks here will help this guy do those two things.

The bigger the tire, the easier it is for everything (cont/motor) to heat up.

Please do not buy a B.S.O. Bicycle Shaped Object from any department store. BSO's are POS's!
Go ahead and buy a brand name bicycle from the online classifieds!

Do not cheap out!
Buy the battery you require, and buy a good charger!

Here’s a contender! https://seattle.craigslist.org/est/bik/d/marin-kentfield-e3-bike/6626913634.html

Another basic hybrid in xl flavor: https://seattle.craigslist.org/see/bik/d/mens-bicycle-for-sale/6601716101.html

And another one! https://seattle.craigslist.org/skc/bik/d/specialized-sirrus-hybrid-bike/6621894460.html

Last one is the best choice I think. Don’t worry about not having disc brakes. The v-brakes on these bikes are extremely strong and will stop just as well as the lower end mechanical discs.

Either of those bike you have will work fine. with 1500w, you won't be doing speeds that aren't possible with peddling alone (dependent on gearing). The biggest issue will be the stress on the rear dropout from the motor. You can counter this to a degree by using torque arms. Just inspect it regularly and maintain the bike properly and they will be fine.

They will likely be a lot stronger than a walmart mountain bike and with better quality running gear.

What rim does your kit come with? Does it support rim brakes? This is something to be weary of as a lot of the kit rims are disc brake only and if your bike doesn't have disc brakes then it can be difficult and expensive to upgrade them.

Be weary of your reclaimed cells. You should really test each one to identify their capacity so you can make sure you are matching them up correctly. The Opus BT-C3100 is a good charger that can test the capacity of cells.

If you match up low capacity ones with high capacity one you will have a poor performing pack and you will risk stressing cells and potentially venting some of them. If you are unsure of the current they can comfortably deliver then it may be wise to use quite a few of them in parallel.

Thanks for the donor frame recommendations but I prefer one that has at least front disc brakes and front suspension (again, I'll upgrade bike components later, I just wanna get down to the e-bike tinkering part LOL).

Looking at pictures of 29ers, I'm starting to worry, because I plan to use the 29er almost strictly as a hybrid/commuter bike... will I be able to add a trailer, fenders and rack to the frame of a 29er (and not the saddle's stem/post) like you can with a hybrid/commuter? Will I be able to ride upright?

Your project will suck till you get a stronger steel beach cruiser, if you go Walmart aka bike shaped object. the frames are always the weak point of that grade aluminum MTB bike. It will wag its tail like a dog when you pedal, so much frame flex.

What you need is the strong frame of the classic beach cruiser, of the kind that has the extra frame stiffener up front.


Like this one. order it shipped to store. Usually these are only in 26", but here it is in a 29 er. (700c rim)
https://www.walmart.com/ip/Schwinn-29-Men-s-Midway-Cruiser-Bike/48520148


It has what you need, a stiff steel frame, 700c wheel, fatter tire, 7 gears, and rim brakes. Good to go, even at your weight, to 30 mph.

IMHO: since you are DIY, it is highly likely that you will revisit and rebuild whatever you make initially anyway. I would buy a Walmart steel frame, knowing that it has a limited life. Build on it, ride it, see what you like and don't like. All of your electronics and motor are swappable to the next build. After 6 months or a year, you will have a feel for what you want. You will develop a familiarity with your motor system. You might find that you really like suspension, or you might find that the streets that you routinely take are ok. 1500watts
may (and probably are) quite enough for your needs. You have the kit, build it, ride it, learn from it. Absolutely insure that you install torque bars if you are using the aluminium frame.

You are gonna love it anyway...

Novaraptor

novaraptor said:

IMHO: since you are DIY, it is highly likely that you will revisit and rebuild whatever you make initially anyway. I would buy a Walmart steel frame, knowing that it has a limited life. Build on it, ride it, see what you like and don't like. All of your electronics and motor are swappable to the next build. After 6 months or a year, you will have a feel for what you want. You will develop a familiarity with your motor system. You might find that you really like suspension, or you might find that the streets that you routinely take are ok. 1500watts
may (and probably are) quite enough for your needs. You have the kit, build it, ride it, learn from it. Absolutely insure that you install torque bars if you are using the aluminium frame.

You are gonna love it anyway...

Novaraptor

Click to expand...

Thanks! This is exactly what I imagined my initial ebike experience to be too.

I got lucky and picked up a 2013, or later, XL Nishiki Colorado 29er off Craigslist this past Friday. This bike checks off everything on my updated wish list for a conversion (beefier frame, mechanical disc brakes, front suspension, wider tires) so I guess I'm almost ready to finally start putting this together. One remaining question is the gears/speeds; the bike is 8 speed, but when choosing the options when purchasing the ebike kit I chose 7 speed (the highest available) and it included a 7 speed freewheel. Can I simply re-use the bike's 8 speed freewheel or is the motor hub made as a 7 speed and I must use the included 7 speed freewheel (and buy new 7 speed shifting system)?

Just use the 7 speed freewheel on the motor, then adjust your derailleur stops, the little screws on the derailleur to limit movement to 7 gears on the new freewheel.


It will be ever so slightly off at one end of the gears, so if you ride road, set it to run smooth on gears 5 6 and 7 by adjusting the barrel nut on the shifter, shortening or lengthening the cable. If you ride trail, then you might prefer it to run smoothest at gears 3,4,5. You can change that setting on the fly, as you ride, or on a brief stop.

You could change the shifter itself, but since most e bikes only run in the highest gear, or at least only one gear 99% of the time, why bother. And with a twist of the barrel nut, you can always make it run smooth in any gear. Particularly not worth the bother if you ride 30 mph, and your pedal gears only go to about 25 mph.


The main thing is set the derailleur itself so it doesn't get to try for 8th gear, and send the derailleur to scratching into the motor case.


8 speed gear would need a wider back end of your frame. its possible, but only if the axle is a lot longer than it needs to be for 7 gears.

And you shouldn't have to worry about your chain. An 8 gear chain will in most cases, if not all, fit a 7 or 8 gear. If you went to 10 gears, you would need a thinner chain. True enough, you won't be using more than 3 gears anyway, and if you have a 3 gear front you may find that setting the rear on the next to the smallest or smallest, all your shifting will be on the front. (Unless you have a really tall hill). Onward.....

The seller said the bundled 7 speed freewheel is optional - I can simply re-use the bike's 8 speed freewheel with the kit's motor hub wheel. Thanks though for all the input on that.

Now, I just gotta figure out how to efficiently determine the capacity of these salvaged 18650's (or just buy new ones if I get too lazy LOL).

Thanks everyone for your help one this whole thing - because of y'all I have the confidence to move forward.

Are you sure your bike has a freewheel? Most modern bikes have a cassette that attaches to a freehub. These are two quite different and incompatible setups.

FWIW, the cheap freewheel that came with my ebay kit wasn't very good and made noise. So I upgraded to a DNP freewheel from Grin and frankly would suggest doing that from the get-go. Not getting a freewheel with the kit is probably no great loss. Just be aware that you probably do need to get one. It is unlikely that a circa 2013 bike came with a freewheel.

wturber said:

Are you sure your bike has a freewheel? Most modern bikes have a cassette that attaches to a freehub. These are two quite different and incompatible setups.

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Ah, I didn't know that. I don't have time at the moment to take the wheel apart and investigate - I took pictures (attached), can someone tell by looking at them and determine if it's freewheel or cassette?

Cassette.