Seeking info - first E-bike build...

[Martinjmpr]

Hi all. I signed up for this board because I'm interested in building an E-bike from a kit.

My bike is a GT mountain bike, 21 speed, that I bought in 2007. It is a hard tail with a front suspension.

I'm thinking that I want to go with one of the relatively inexpensive (<$300) kits from Amazon. There are a bunch out there, I think most of them use the same Chinese motors.

I would add as big a battery as I can afford, likely a ~15ah mounted on a rear rack.

I'm thinking that a 750 - 1000w 48v rear hub kit would be the best way to go.

My biggest concern is that my bike has Shimano trigger shifters with the brake levers integrated into the shifter body (basically there's one big piece on each handlebar that contains the thumb shifter, the finger shifter, and the brake lever.) Some of the kits have a throttle assembly that goes on the right hand grip that includes the controller and my thought is that this would not work on mine since the shifter would be in the way. Just wondering if anybody out there has done an E-bike conversion with trigger shifters.

Also, my GT has rim brakes, although the frame has mounting holes for disc brake calipers. Would it be a good idea to put a disc brake at least on the front wheel?

Or would it make more sense to just start with a bike that already has disc brakes (as most bicycles seem to these days.) I don't know how difficult/expensive the disc brake conversion would be.

Also wondering if it might make more sense to start with a bike that already has twist shifters and separate brake levers vs. my trigger shifters and integrated brake levers. I do know that you don't HAVE to use the included brake levers but I'd like to at least have the option (since the included brake levers usually stop the motor.)

Thanks in advance for any help!

Attaching photos of my left and right handlebar "pods" as well as the front and rear caliper mounts.

 

[harryS]

You have disk brake mounts on your frame, which makes it all possible. Conversion isn't hard, but the costs do add up. I've had good luck with Avid BBS7 calipers. A set of those with rotors is about $70 on ebay. Then you need a new front wheel that can take a rotor. Another $50-70. The motor hub will be compatible. You could consider hydraulic. I have a set to install in the Springtime on my 26" e-fat bike as as a test, along with larger rotors. .

I have bought the Shimano Acera ML-310 trigger shifters and they work well with a throttle on either side. Those are about $17 for the pair.

I've done the above several times on conversions. I've found the ML-310's work well and often appear on bikes that I bought. I've converted a couple of other bikes to disks and think the BBS7 is my minimum starting point. I have tried with some no-name calipers and also the BBS5. They weren't too consistent. At the same time, my first ebike still runs v-brakes, and I think they work well.

That rear drop out looks a bit holey. Better include torque arms. So you're going to put a 15 pound motor in the rear? I've yet to install a heavy motor. Mostly 5 pound and 8 pound motors. 250W and 500W. Never planned to compete with cars.

I've had throttle faults ...two different bikes. If you lose the ground wire, bike takes off. Both bikes had 5 pound motors, so you could barely tell. WIth 1000W, you'll know, and you will want a brake cut-offf.

 

[indianajo]

At the same time, my first ebike still runs v-brakes, and I think they work well.

Must never ride that bike in the rain. I hit a car that ran a stop sign with rim brakes. I had stopped at the 4 way, was only going about 3 after crossing one lane. My reaction time is 56 ms. Rim brakes are garbage, I've hated them since my 2 speed bendix coaster brake hub bike was stolen, forcing me to buy a 3 speed rim brake bike. I do ride in the rain, it rains 153 days a year here and I don't drive a car.
You absolutely must have one brake handle with cutoff switch. These controllers are so cheap the heat sink is fake because most are not connected thermally to the transistors. Nice decoration, that aluminum case. A fet could short out at anytime besides the throttle problem mentioned above.
If you ride flat and fast you want a DD hub motor, which weighs significantly. If you climb a lot of hills or stop at all the signs & lights you want a geared hub motor, uses a lot less electricity and accelerates faster. If you climb long steep grades, 12 minutes of 15% will burn up a geared hub motor, MAC says. You'd have to put up with a DD or go mid drive. Warning, most mid drives besides shimano & yamaha drag the motor with your feet unpowered. I ride mostly unpowered, the motor is for too much headwind or trips over 25 miles.
I've got torque arms, and my motor is in a steel fork on the front. I made them out of bed frame rail. The advantage of front motor, I have an 8 speed 11-32 rear sprocket cluster with SRAM derailleur. Hub motors come with cheap 7 speed 14-28 clusters. The country of origin indicates to me the steel is probably soft. 28 is not big enough to climb 15% with 60 lb supplies without the motor. 14 is not tall enough for me to help the motor over 12 mph. 8 speed freewheels won't fit the rear fork, I bought 3 and neither sun nor shimano provides dimensions much less the ****ese suppliers on ebay. I could never find a 11-32 7 speed freewheel in stock anywhere although they are in catalogs. So I changed from the rear DD motor to the front geared hub motor from ebikeling. He no longer sells 48 v geared hub motors.
Ebikeling sold me disk brake rotors & calipers for about $24 the pair. Seemed competent. I didn't use them, I didn't like the battery mount I made for the Huffy Savannah, abandoned that project because the 2 LiFePO4 batteries I bought for it were garbage. Buy a battery from lunacycle or ebikeling in the US is my advice, expensive but worth it. Btrbattery of amazon and sun ebike of baldwin hills CA via ebay were both selling garbage. Got the money back from Amazon but it took 3 months to prove the ebay battery was bad instead of the motor or controller, so I didn't get my $330 back from that.
Don't buy ebikeling display, it was 40% inaccurate, didn't display speed or distance if the motor was off downhill, and fogged up in the rain. Waste of money. What works is green-yellow-red voltage LED on the throttle with the $189 DD kit.
Your brake/shifter appears to be irreplaceable. If you buy a kit with a throttle, you won't be able to install it. If you buy a PAS only kit, then you might be able to keep your existing bike. You can fail to install the throttle on a kit with PAS if you wish. Be sure your kit includes a magnet wheel & pickup. I don't know if that coutoured grip on the left can be removed to install the Pas level on/off control. A cheap kids mountain bike from the flea market may be in your future, at least they have steel frames. Of course if you're 6' or taller, those kiddie frames won't fit. I rode them for years since I'm 68". Don't buy the 6 speed rear models, the axle broke on me because they are 5/16". I weighed a whopping 180 lb at the time. Riding unpowered most of the time has got me down to 165 lb. With the motor, no more 6 hour ordeals to get to the city if the headwind is 25 mph in September like 2018.

 

[Browneye]

Do-able. Did the same for our Specialized Roll. But it already had disc brakes. You can buy cable Tektros for pretty cheap - if they fit that would be the way to go. The problem is you'll not only need the brake kit but also a way to attach the front disc - so either a new hub or wheel assembly - likely cost more than the brake kit. But yeah, you want disc brakes for a e-bike due to speeds.

You can replace the trigger shifters with seperate components from your brake levers - I have a Shimano 7spd if you need one, cheap. I actually removed the front dereilleur and replaced the 3-chainring crank with a single speed, really cleaned things up. Wife never shifted it anyway, and this simplified things - put the thumb throttle on the left. You might get by with your existing brake levers with cable actuated disc brakes. The magnetic motor cutoff sensors are easy to install and work fine - they are an option on the kits in lieu of new brake levers with switches in them.

The Bafang geared hub kits work really well, components are good, assembly was super easy on ours. Consider sourcing from Greenergy or Bluenergy - they build the wheel assemblies and package the whole thing with a good battery if you want. Or get a battery from Em3EV, Luna, or Ca-ebike. Don't just source a cheapo battery pack of unknown source - there's some real junk out there.

There are two hub sizes - 158mm diameter and the 170mm - I recommend the larger, with a 48v battery it's 500watts nominal, will push the bike to 30mph if you want or need it to, albeit at the cost of range. At the time of purchase a larger capacity pack is at nominal additional cost, maybe a hundred bucks. This is the hub they are installing in bikes with a 52v battery and calling it 750watts IIRC. The smaller one is 250/350/500 watts depending on pack voltage.

Figure you'll spend nearly a grand to do this, so weigh whether it's worth it to convert an old bike, or just put a few more bucks with your funds and buy a fully built ebike.

Another option is a Bafang mid-drive conversion - they're a little more money but seem to have good feedback on them. @Thomas Jaszewski can be a great source of info on this drive system.

Let us know what's next...this forum was the impetus to do our conversion and we're very happy with it. The bike I had was not a good candidate - rim brakes and carbon fork, so I sold that one and got the Giant Explore. Also beyond thrilled with it, although it was quite a bit more $$ than the conversion. Especially since we already had the bike.

 

[PDXzap]

No advice to give, just a welcome!

 

[tomjasz]

Save your money and buy a reliable kit from a source with support. You'll get nothing from Amazon. All those kits are cheap clones. Unless you want a new hobby, buy from a reputable shop.

 

[harryS]

Ebikeling's 500W geared motors from amazon are fine. I've installed three (from ebay) since 2015. His newest LCD controllers have bad pedal assist though. Never tried any 1000W motors.

The choice for budget ebiking is moving to buying vs build, as the variety of bikes and quality of the low cost imports gets better. Aside from it being a fat tire bike, I like the 20" electric fat tire folder I bought on Amazon last year for $779. It ran a little too fast in PAS1, so I upgraded the controller to a 5 level PAS.

 

[tomjasz]

Ebikeling's 500W geared motors from amazon are fine. I've installed three (from ebay) since 2015. His newest LCD controllers have bad pedal assist though. Never tried any 1000W motors.

The choice for budget ebiking is moving to buying vs build, as the variety of bikes and quality of the low cost imports gets better. Aside from it being a fat tire bike, I like the 20" electric fat tire folder I bought on Amazon last year for $779. It ran a little too fast in PAS1, so I upgraded the controller to a 5 level PAS.

But do you think that those of us that are DIY fellas with multiple bikes might have a better experience than a new builder or someone with a single bike that is going to put a lot more miles on? I don't mean to be argumentative but I field several calls and emails every week from another builder that is frustrated with the support of their Amazon kits.

In my experience, most beginner builders are happier with fewer issues. And I think especially those that anticipate high use should consider better kits.

 

[indianajo]

I've got about 3000 miles on an ebikeling 1200 W 48 v geared hub motor from 2018. I've got 500 miles on a DD hub motor from ebay, labeled "48 v 1000 w Lysing". Neither motor has caused a problem. I trust the motors so much I have already put a MAC12 geared hub wheel kit from Luna in the garage that would take me <8 hours to install. I expect the ebikeling geared hub to get me home unpowered after it fails, as I pedeled home unpowered 16 and 24 miles when the trash batteries failed.
I hated the PAS that came with the ebikeling kit, it had a minimum speed of 11 and accelerated to that speed with 500 W. That is too fast for the 8" of pavement I have outside the line & rut on Hwy 3. Also too fast for my driveway. I hated the ebikeling display that was 40% fast, showed distances 40% too far, and zeroed everything downhill where I spend 1/2 my time. So I am using the throttle only no display ebay kit controller etc. I expected no support from ebikeling or the ebay vendor, and asked for none. Ebikeling forgot to ship the disk brake calipers & rotors I ordered, and corrected it promptly when I emailed a complaint. Ebikeling has an installation video which is partially correct, but doesn't show which side of the pedal pickup is the sensor. I found that out by installing it backwards first. Installation was complicated by my not using a 2018 standard bike, but a $15 199? huffy savannah with a one piece crank that looked nothing like the one in the video.
Batteries, as I've said, use luna, ebikeling or send your debit card # out into the international cyber war zone. The vendors of battery trash were highlighted in post # 2 but they of course have changed their names.

 

[Martinjmpr]

Thanks sincerely for all the input. It's a lot to digest, but the gist of what I'm getting is that this is possible, but before I even order my electric kit, it would be wise to:

1. Change the shifters for something non-integrated with the brake levers, and

2. Upgrade to disc brakes. The kit should come with a disc compatible rear wheel, correct? So since my frame is already set up for discs, I'd really just need a disc compatible front wheel in addition to the brake kit, yes?

 

[indianajo]

Yes, the rear wheel kit usually comes with brake rotor flange & holes. I had to thin down the mount block on my tektro caliper to use it. I used a nicholson mill file. I also had to buy 4 mm mount bolts with thinner round heads. The heads on the caliper screws that came with the motor were scraping something. You'd need a front wheel for disks.
Browneye said something about magnetic brake sensors, which might avoid installing the brake handles that come with the kit. But this requires splices in the brake cutoff wires, other mechanical & electrical design work, and may be a bit complicated to be a reliable safety device. If the magnetic kit comes with the exact connectors that is on the brake levers, I stand corrected. My 2 kits came with 2 different kind of connectors on the brake levers, so there is nothing standard about them IMHO.
BTW the reason I did not buy a bafang geared hub motor 12/17 was that the only ones I could find in the USA were for fat tire wheels. I don't own or want a fat tire bike; they are the banana seat of the 21st century. I ride 2" tires which are comfortable enough at 10 mph.

 

[Browneye]

Thanks sincerely for all the input. It's a lot to digest, but the gist of what I'm getting is that this is possible, but before I even order my electric kit, it would be wise to:

1. Change the shifters for something non-integrated with the brake levers, and

2. Upgrade to disc brakes. The kit should come with a disc compatible rear wheel, correct? So since my frame is already set up for discs, I'd really just need a disc compatible front wheel in addition to the brake kit, yes?

1. Not necessarily required. It really depends on what kind of disk brake conversion you intend to utilize. I can't tell you for 100% sure that Tectro cable disk brakes will work with your existing levers, but 95% sure. You can then use the magnetic switch type sensors for motor cutoff with your existing shifter/lever combo. If you go with hydraulic actuated then you'll need new trigger-shifters. As I mentioned, we decided to change out the crank to a single chain ring since she never used the low and high front gears. This simplified the lever situation and cleaned up the derailleur area low on the seatpost tube. On the right we still use the integrated shifter/brake combo and it works fine.

2. The hub and wheel kits do come with a flange mounting surface for your disc rotor. You'll be tasked with ensuring your caliper lines up with the rotor on the new hub. There's no guarantee everything will line up, but again, it's reasonable that they would. Just be prepared to do some adjusting, trimming, fabricating, etc.

If you're a handy DIY'r this is a fun project. If you're admittedly not so much these can turn into a complicated nightmare. And know that there is virtually zero tech support or warranty backup. Getting hold of someone in China for a claim and actually getting service can be an exercise in futility. I went in with my eyes open, and if I couldn't get warranty help I was prepared to buy parts to get things going. I have not had any failures or issues, and we have several hundred miles on her conversion and it's just dandy. But I'm pretty mechanically inclined, having built or restored many motorcycles, cars, boats, airplanes, and done all facets of home building.

You'll also need a crank removal tool, both for pedal arms, as well as for the race retaining nut in the crank bearing, in order to install the pedal sensor. And if your kit doesn't come with a cassette you'll need a tool to remove the old one and install on the new hub. Make sure you can determine if you have a freewheel or cassette type gearset. The kit I got came with a new freewheel gear set so all I had to do was thread it onto the new hub.

You'll also need to address your battery pack attachment if you're using a bottle cage mounting bosses. If you're going to install a rear rack mounted pack then a rack that will fit your frame.

Maybe post a pic of your bike?

Here's the conversion I did on wife's Specialized Roll. It is a good candidate for a conversion due to it's balloon tires, disk brakes, and bottle-cage mounting. And it's a comfortable upright cruiser, and she already loved the bike.

This first pic shows the lever and controls setup. As mentioned, I ordered a separate trigger-shifter for the right side, but the integrated one actually fit better so I kept it. I also found the brake cutoff mag switches work fine. I have since moved the throttle over to the left side since the shifter on that side is gone now. It can be a challenge fitting everything on the bars and getting it all to work together.



Single-speed crank conversion:



Crank mounted pedal sensor:



Hub drive:

 

[harryS]

Your dropouts don't look strong enough to support a big motor.

The first pic is yours, showing how they cast the frame with air around the axle. That's a 10mm diameter axle if your didn't know. A motor axle, shown in the second pic, is 12mm x 10mm. If the space is limited, as in your bike, installers often deepen the slot by 1mm so that tit remains centered, and the axle nuts fit in the same place.

I don't think you have a lot of room. If it were my bike, I'd pick another one. I was in this exact scenario with my first one. I posted that 3rd pic in August 2015 showing the progress of my first install an an alloy frame diamondback. Was advised to get torque arms.

I changed to a steel frame Trek that I also owned. Glad I did.

 

[Browneye]

Ah, I missed the pics in the first post.
And that rear axle mount looks sketchy.

If it were me, and I wanted a hub-drive ebike, I would pony up a few more $$ and get a built one. From all the options around, reviews and such, I'd probly look hard at Ride1Up 500-series for $1099:

500 Series (Discontinued) - Ride1Up | Best Value Electric Bike 2021

One of the most popular ebikes available; all-surface bike designed for comfortable touring over long-distances and speeds of 15mph

ride1up.com

You're going to spend nearly that trying to convert your old bike. And if you buy a good donor bike you'll be in it for way more to convert it.

BTW, your "$300" kit doesn't include a battery - they cost more than the kit. Plus a brake conversion, hub, some tools, etc.

Another good budget hub-drive bike is the Aventon Pace 500, about $1400. You might get a dealer to knock a hundred off if you assemble it yourself. I think they ship direct as well if you don't have a local ebike dealer.

Both of these are on 650b wheels - 27.5. For 700c wheels you have to step up a bit in price, they're generally a little better component-wise all around.

Another option for your existing bike is a mid-drive conversion. From what I found, you'll be in it way more than either of these two new complete bike options.

 

[Martinjmpr]

You make good points with your comments about the strength of the frame. As far as the cost issue goes, yes, I know the battery is the most expensive part of the conversion.

A part of the reason I wanted to do my own is to save money but I also just thought it would be fun. But between the less-than-ideal frame and the other issues I'm starting to think a pre-built bike might just make better sense.

I have to admit, I had some thought of just buying a cheap thrift-store bike for $30. Most of those have rim brakes and twist shifters though, with no real option for disc brakes.

Thanks again for all the guidance!

 

[tomjasz]

Your dropouts don't look strong enough to support a big motor.

The first pic is yours, showing how they cast the frame with air around the axle. That's a 10mm diameter axle if your didn't know. A motor axle, shown in the second pic, is 12mm x 10mm. If the space is limited, as in your bike, installers often deepen the slot by 1mm so that tit remains centered, and the axle nuts fit in the same place.

I don't think you have a lot of room. If it were my bike, I'd pick another one. I was in this exact scenario with my first one. I posted that 3rd pic in August 2015 showing the progress of my first install an an alloy frame diamondback. Was advised to get torque arms.

I changed to a steel frame Trek that I also owned. Glad I did.

View attachment 43797 View attachment 43801 View attachment 43802

Hey Harry!

whats the design intent with the space I outlined? ive a couple of different torque arms that were custom cut I wonder if this would be a good idea if this frame is used.

 

[tomjasz]

who configured this bike? That dropout has piqued my interest

 

[harryS]

Tom, the black frame belongs to Martimjmr. I've very little training as a mechanical engineer, but seat of the pant sez to avoid a big motor. You might have more metal on some alloy front forks.

Martin will have to ask himself what he is looking for in an ebike. Me, I just wanted my first one to keep up with my wife on her new ebike, but she rides slow. I didn't need tp go over 20 mph. I didn't need to ride amongst traffic and stop on a dime. RIm brakes on a Trek 830 with a 36V motor and 10AH battery work fine for that. I initially put $500 into it ($280 battery, and $220 for motor kit). It's a simple 3 level PAS, but the levels suit my riding style perfectly,

 

[Martinjmpr]

Thanks for all the input. I'm still on the fence of build-vs.-buy.

So with regard to my forks, would a build with a less powerful motor be less risky? Say a 250w motor?

Problem there is that I'm still faced with the dilemma of replacing my current shifter so I can use the brake levers that come with the kit and stop the motor.

 

[Browneye]

Ya, you don't need to change your shifters. The kits come with an optional magnetic sensor that can be installed on your existing brake levers - they work just fine. Your bigger issue is getting disk brakes to work, and adapting everything to an older frame. You're going to spend nearly what it costs to buy a new fully built ebike.

Also know that when you quit pedaling the motor shuts off, unless you're holding a throttle on.