Help with rear motor and single speed cruiser

[HornetB]

Hi guys.

I've been reading and reading and getting a lot of information, but I might have to ask a question myself. Hope someone can help.

I have a Felt cruiser, single speed with coaster brake with 3" tires. I love the bike and the ride and style but it's a little heavy with a single speed to ride to work so maybe time for a motor. The coaster brake is pretty poor so I'm reluctant to use a front hub motor and rely solely on the rear brake, so my plan is to install a rear motor and then switch out my front hub with a sturmey archer drum brake (very good reviews apparently and I dont have disc tabs on my forks). The drum brake will be a very simple switch out with a rebuilt front wheel and be more economical than going to disc brakes because of the need for new forks, new hub, disc calipers etc.

My question though is I have 3" wide tires on the rear, to deal with this my coaster brake hub uses an offset rear sprocket to clear the tire. The center line of the sprocket sits 10mm inside my right hand side rear drop out (space between drop outs is the typical 135mm). I'm nervous that if I get a single speed free wheel rear motor that the chain may not line up and hence rub on my tire.

Can anyone with either crystalyte (40X), bafang or other rear hub motors give me a measurement of where their free wheel cog sits in distance from the inside of their drop out? I'm wondering if maybe I just get a 3 or 5 speed freewheel (no changing gears) and just use whichever cog lines up with the front sprocket and give me tire clearance as well but it's a bit of a mystery bag on exactly which gear I will end up with. I don't really want the gearing to be too tall.

At the moment I'll be getting a rear wheel built with whichever motor i decide on, not sure at this stage whether to go for a clyte or geared bafang or another option (aren't too many in rear??). I'm in SoCal and only need to ride 5 miles to work, very flat riding really with a few low grade hills (really quite low or short). The bafang appeals on price and I know I will have the torque to haul my heavy cruiser and me up the inclines but maybe the clyte is a better choice? Only really want a speed of 20-25mph (30 would be nice for bursts with good brakes but I'd settle for slower).

Would the bafang and infenion controller be a good choice and the I just volt it to my desired speed. It seems a nice option because I can add disc down the track and the price is nice given I have the cost of building the wheel anyway (I'd prefer wide rims).

 

[E=IR]

I can't help with your specific questions but just wanted to say that bike is beautiful.

I think your rear wheel Xlyte and front wheel drum brake is the right way to do it. How were you planning to put rear brakes on it?

 

[HornetB]

Thanks for the compliment. It sure is a nice bike to ride so it would be cool if I can turn it into a practical ride for work. I like the looks of it as is so I kind of want to stick with the theme and do a subtle conversion and keep things as low key as possible. With a hub motor it will just be an awesome cruiser for getting to work and general cruising.

As for rear brake that's part of the appeal of the bafang cause it is a small hub, I'm hoping I may be able to make a disc brake work with a disc brake adapter (more reading needed on this). I think the crystalytes seem to have problems with caliper clearance (??). Most braking is done with the front anyway, but agreed a rear would be nice too.

Open to ideas. Cheers, Justin

 

[Anonymous]

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[dogman dan]

Indeed, it won't take much of a motor to make peadling useless. A very simple low watt, 36v motor may be the best option. Front or rear, its a custom wheel build for sure. Well worth it for that bike. Maybe you can find a 52 tooth front srocket that can be mounted to the existing sprocket with bolts to give you a faster peadling speed. Most cruisers get hard to keep feet on the peadles above about 12 mph.

 

[fechter]

Nice bike.

The alignment of the tire with respect to the chain will depend on the amount of dish the wheel is built with also. If the person building the wheel knows the dimensions of the tire etc., the spokes can be dished to accomodate chain clearance. The hub motor itself may be more than 3" thick, so dishing may not even be necessary.

It would look cool if the front drum brake was similar looking to the rear hub motor.

If you use a direct drive motor, you can wire it for resistor (or regen) braking.

Now, where to hide those batteries....

 

[docnjoj]

I have a Bafang with a 5 speed freewheel and it does not line up perfectly with my 6 speed SRAM Twistgrip. That said, however, it is really a minor problem to twist a little past the click point and let the gear shift perfectly! I may get rid of the detents and use it as a twist shifter, cause I gotta shift a lot for stop signs. If it really bothers me, Ill change to a regular 5 speed Shimano 5 gear freewheel! The one on the Bafang has wider gear spacing.
otherDoc

 

[HornetB]

Thanks guys. Appreciate the help.

My rear wheel isn't dished at all currently, so I doubt I'll have to dish it at all with the motor. Still sounds like I might need to get a 3 or 5 speed freewheel to get one to line up but I guess I'll have to work that out with motor in hand. With a 5 speed free wheel I'll get one of the cogs to line up, it just might be a little tall in the gearing for pedaling without the motor but as you say above 12mph or so my pedalling probably wont be too effective with the motor anyway.

Guess I'll try and get a rear crystalyte, just hope I can get one thats got the grunt to pull me and my heavy bike up the gentle slopes without too much trouble. I'm wondering if a 406 might do it at 48V or if I should go to a 408 for a bit less speed and a little better climbing. It's kind of hard to work out what one person calls a hill and another calls a slight rise. Having only played on a WE front 36v bike for 2 mins I dont have much experience to make the call.

Thanks again guys, still open to anymore comments or idea if anyone has them.

Cheers.

 

[E=IR]

Ummm

More speed is bettah

 

[Anonymous]

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[Daniel828]

Thats a great bike to start with. I like the looks of the Felt cruisers, plus you have the coveted Thick Brick tires. The Euro guys mount those on wide (like 80mm-100mm) rims. They look so cool.
Anyway, I'm in the same boat as you HornetB. I have a custom frame from No Name Customs and it was intended to be used wth a rear coaster brake.On the front I'm using Nirve forks with a shimano mechanical disc brake. My set-up is a Crystalyte 5303 Pheonix racer on the rear with no brake, running a 72/40 controller at around 80 volts.It goes about 37-40 mph.
Like fechter said, you have to dish the rim to the left so that the chain will clear the tire, if looked at from the rear. This setup works well.Any questions I'd be glad to help.
I have a video on youtube and some pics. on austinev. It's called 66 volt bobber.
--Dan

 

[HornetB]

Thanks guys, I'm getting some great feed back and think I'll know where to head on this now.

FWIW regarding the Thick Brick tires, if you can get them on you bike they rock as a tire. I can lean this bike so far over it scares me (it will probably lean further but I think I'll fall off). I've never experienced so much grip from bike tires on roads but then I guess I've always run knobbies on my mountain bike, must have to do with the profile of the tire and lack of knobs (maybe other street tires are as good??). When you lay my MTB over you can first hear the knobs starting to flex followed by the inevitable wash out. These Thick Brick tires are far more reminicent of road motorbike tires.

Looks like I'll go for a crystalyte rear, regen or disc brakes for the rear if I can find the controller to do it. Controller that can go to 72V but run lower. Drum brake on front in relaced standard rim. Sounds like I'll be able to get the rear to work with some sort of free wheel, I'll just have to have a good chat to my bike shop and leave them the frame and wheel to make it work.

Thanks guys. HB