Kit options mid drive beach cruiser build with 4 speed igh with coaster brakes?

[reevesbyron02]

I have a Electra deluxe cruiser that has a internal gear hub a Shimano Nexus 4 speed with coaster brakes I live in Seattle so I was thinking a mid-drive with optional gears in the back would be best for the hills any info I can find seems to be 2 years old and everyone says the only kid that is compatible is the tsdz2 coaster version can anyone tell me if there's any other options these days?

 

[lnanek]

> so I was thinking a mid-drive with optional gears in the back

My Shimano IGH definitely can't fit more than one cog in the back, so not sure how you'd do that unless you mean ditching the IGH entirely and getting a new rear wheel with a cassette or freewheel.

That said, most mid drives add power at the crank and so make use of whatever gear your IGH is in - same as your pedal power. There's some ancient ones that add a separate chain on the other side of the bike which would need its own cog back there. Preferably added by disc brake rotor mount, but there is an ancient rag joint option where you pancake the gear on to the spokes.

Why not just put a front wheel hub motor on?

 

[Chalo]

Front hub motor is a good option. I would not try to stuff superhuman power though an internal gear hub that wasn't intended to work with a motor.

 

[neptronix]

The weight balance of that bike is really rear heavy due to the handlebars being so high.
I'd be cautious about adding much power to the front wheel because the traction won't be great. That front fork isn't very strong either. Maybe a 350w motor, tops.

Mid drive? i dunno, does it have a standard 68mm bottom bracket? i also wouldn't go high power because the IGH could be weak.

This bike isn't very ideal for conversion.

 

[Chalo]

The weight balance of that bike is really rear heavy due to the handlebars being so high.
I'd be cautious about adding much power to the front wheel because the traction won't be great.

Every Electra Cruiser, Electra Townie, KHS Manhattan Smoothie, Fuji Saratoga, and other such rear weight biased bikes I've converted got a Bafang G020 front motor with a 22A controller. Not one has been a problem under any sized rider. They can all scritch the front tire from a dead stop, and they all scrabble a little bit on decomposed granite or fallen leaves. But they stay up because a powered front wheel still pulls in the direction you point it, even if it's slipping.

My honey fell off of hers twice in one ride last month, but it was due to overzealous braking on a loose surface, and not motor power.

That front fork isn't very strong either.

I'd inspect and make an informed decision about the fork tips, but the truss that fork has is a functional reinforcing brace. It's almost certainly better than an unbraced fork with the same size steer tube. I can't tell from the photo whether it would be an ordeal to fit a torque arm to those fork tips.

I think it's a pretty good candidate if he's not doing the classic "I don't know anything and I want to go 50 mph" nonsense. Build it and ride it like it's a Class 1/2 e-bike and it will most likely be just fine. But don't put motor power through the internal hub gears.

 

[neptronix]

I've experienced tire slippage on said bikes with handlebars like that and 800w of front motor. You can only compensate with huge tires. I personally feel safer on a bike that goes 3x faster but doesn't experience front wheel slippage.

Yeah, the fork has a truss but i've seen stronger forks, i would expect that one to be kind of bendy and twist under acceleration.

 

[docw009]

How about buying an electra fork, the one they use on their electric model which has disk brakes, They have pages of forks for about 99 bucks. Then you'l lhave something that can take a front motor and augments your braking too.

Bike forks - Electra Bikes

electra.trekbikes.com

 

[reevesbyron02]

First off thank you all for your time and knowledge!! I forgot to mention I'm also going to be changing the forks at first I was pretty set on putting a regular springer style forks but I'm leaning towards the double springer style forks I don't know how well a front hub would work for traction issues , I was also leaning towards a sturmey archer front brake hub, does anyone know if the tsdz2 coaster version is 250 or 350w?

 

[reevesbyron02]

The weight balance of that bike is really rear heavy due to the handlebars being so high.
I'd be cautious about adding much power to the front wheel because the traction won't be great. That front fork isn't very strong either. Maybe a 350w motor, tops.

Mid drive? i dunno, does it have a standard 68mm bottom bracket? i also wouldn't go high power because the IGH could be weak.

This bike isn't very ideal for conversion.

I picked up a decent micrometer from harbor freight this morning I'm gonna measure my crank when I get home from work here in a few, I have the same concerns about a front style hub especially with the hilly terrain here in Seattle I forgot to mention that I just ordered a new seat, new shifter and linkage, and I was gonna change the forks with a regular springer style forks but have decided to go with double springer forks, and they're disc brake compatible but I kinda wanna go with sturmey archer drum brake in the front (if I go mid drive motor) I think the only coaster brake compatible kit is the tsdz2 and it shows the watts 250/350 so I'm not sure which it exactly is

 

[reevesbyron02]

> so I was thinking a mid-drive with optional gears in the back

My Shimano IGH definitely can't fit more than one cog in the back, so not sure how you'd do that unless you mean ditching the IGH entirely and getting a new rear wheel with a cassette or freewheel.

That said, most mid drives add power at the crank and so make use of whatever gear your IGH is in - same as your pedal power. There's some ancient ones that add a separate chain on the other side of the bike which would need its own cog back there. Preferably added by disc brake rotor mount, but there is an ancient rag joint option where you pancake the gear on to the spokes.

Why not just put a front wheel hub motor on?

I'm not sure what you mean here??? "My Shimano IGH definitely can't fit more than one cog in the back, so not sure how you'd do that unless you mean ditching the IGH entirely and getting a new rear wheel with a cassette or freewheel.".... I'm planning on replacing the forks with double springer style forks the ones I'm looking at are set up for disc brake but I think I want to use a sturmey archer front drum brake .

 

[reevesbyron02]

Update: on eBay I found the tongsheng tsdz2 (coaster brake compatible) for sale and the kit options lets you choose 36 or 48 volts and 250w, 350w, or 500w ( the 250w and 350w kits are $429.99 and $432.99 for the 500w kit)

 

[lnanek]

Typically in every IGH there's a certain gear that's the 1:1 ratio. That gear is usually a lot stronger. If you are really going to run the power of a mid drive through a delicate IGH, I'd keep it in the strongest gear.

Don't think I'd want a coaster brake version either, personally. That means your chainwheel won't freewheel, which means if the motor is running then your pedals will be spinning. So it's incompatible with throttle control, for example. It will also kick a bit when you stop pedaling until the motor detects you stopped and stops contributing.

I'd just throw some v-brakes on the back, disc brakes on your new fork on the front, and order a non-coaster version mid-drive. Pedaling backward won't activate your coaster brake since your chainwheel will freewheel, but that doesn't matter with two other lever based brakes you can use. Meanwhile the freewheel in your chainwheel will prevent the motor from moving the pedals ever.

 

[Chalo]

Typically in every IGH there's a certain gear that's the 1:1 ratio. That gear is usually a lot stronger.

In the Shimano Nexus 4, the 1:1 gear is the bottom gear. In most applications, that's not where you most want to use motor power, but this case might be an exception.

 

[neptronix]

Update: on eBay I found the tongsheng tsdz2 (coaster brake compatible) for sale and the kit options lets you choose 36 or 48 volts and 250w, 350w, or 500w ( the 250w and 350w kits are $429.99 and $432.99 for the 500w kit)

Unless you want to replace your IGH with a stronger one, i'd recommend getting the 350w one if a little over 20mph is a good enough speed.