Crank or Rear Hub?

[Wingreen]

A friend has been impressed with my Big Bear and now wants to convert his bike into an electric bike, as he struggles to get up a very steep hill on his way to work. I suggested he avoided a front hub drive conversion as there would be traction problems, especially when wet. Presumably, he would need to fit a crank conversion or a rear hub/wheel? I thought a rear wheel drive would be best, as I had heard that crank drives can be more difficult to fit (plus, unless used properly, can be problematical) but, having looked through the forums (fora?!) quickly, I'm getting the impression that fitting rear hub drive is actually more difficult than converting a crank drive. Now I'm confused. Any experts out there have a view?

 

[Tugwell Gibson]

Ithought it would be easier as you get a new back wheel with it in place.

 

[Wingreen]

Ithought it would be easier as you get a new back wheel with it in place.

Certainly, that was my original thinking - that it must be easier than fitting crank drive plus, as you say, a new wheel too.

 

[anotherkiwi]

Having done the two much of a muchness...

Hub: dropouts need attention in many cases, torque arm needs to be fitted on aluminium frame. You keep your front derailleur, rear derailleur and cassette if they are the correct width. You may have to stretch the frame a little

Crank : you need the correct tools to remove the crank arms and BB. You lose the front derailleur but keep your rear wheel and gears. Chainline can be a problem especially with more than 8 gears.;

 

[Benjahmin]

Front hub traction is not a problem. On the very steepest (I'm talking 1:5+, with slimey or loose surface) I get some scrubbing, usually handled by putting my shoulders over the bars. No problems with wheel dishing to fit, did have to go up a disc size though, but the the Ezee is a big motor.
All in all front hub is the easier fit imo.

 

[Nealh]

Wingreen do you struggle up hills with the BigBear ?

 

[Wingreen]

Wingreen do you struggle up hills with the BigBear ?

No, no struggling - other than some minor slippage (wheel spin) in one small section of my drive when returning home.

 

[Deleted member 4366]

Forum is second declension, so the Latin plural is fora, but in this use of the word forum, it's really an English word, so plural is forums.

For steep hills and high power, I wouldn't recommend a front motor. I've run into traction problems using a basic 250w Bafang QSWX2 at 15 amps, and front motors make the steering less neutral, plus they're noisier. You have a front motor, so you know the short-comings. They're not a deal-breaker, but a rear motor is just so much better, which is why I recommend one.

I'd say that mid-drives are easiest to fit, though you can get problems with any type of motor. There's not a lot in it, so it shouldn't be a deciding factor. Whatever motor you fit, it's a few hours work, but you're then stuck with it for years, so it's worth investing a bit of time to get the right one.

The rest is simple: Hub motor for commuting and touring; Crank-motor for off-road and mountains.

 

[Wingreen]

Forum is second declension, so the Latin plural is fora, but in this use of the word forum, it's really an English word, so plural is forums.

For steep hills and high power, I wouldn't recommend a front motor. I've run into traction problems using a basic 250w Bafang QSWX2 at 15 amps, and front motors make the steering less neutral, plus they're noisier. You have a front motor, so you know the short-comings. They're not a deal-breaker, but a rear motor is just so much better, which is why I recommend one.

I'd say that mid-drives are easiest to fit, though you can get problems with any type of motor. There's not a lot in it, so it shouldn't be a deciding factor. Whatever motor you fit, it's a few hours work, but you're then stuck with it for years, so it's worth investing a bit of time to get the right one.

The rest is simple: Hub motor for commuting and touring; Crank-motor for off-road and mountains.

Thanks d8veh - as ever, very useful. I think the hill he has to negotiate hardly fits into "commuting or touring", but neither is it "off-road and mountains" (Its Allt Goch Bach just outside Beaumaris, in case anyone knows it). Now...excuse my ignorance but you refer to "mid drives" being easier to fit. Is a "mid-drive" a crank motor? Or a term that covers some other aspect? (I know, I should know by now!)

 

[Deleted member 4366]

A crank motor is a mid-drive.

 

[John_S]

I've rode up Allt Goch Bach on my Big Bear more than once. It is definitely quite a steep hill. I live near Llandudno now and used to live in Bangor. Maybe you (Wingreen) and I will run into each other on our Big Bears sometime .

I think a crank motor is probably easier to fit than a rear hub motor. I would recommend your friend gets a local bike shop or mechanic to fit the kit for him unless he know exactly what he's doing. I'd agree with other posters that a front hub motor is prone to wheel spin, especially when going uphill on a wet day. A rear motor is definitely better I'd say.

My opinion on crank driven bikes is that they are less fun to ride than hub drives, and require more skill. Much more frequent gear changing is required on a crank drive, and it is necessary to be in the correct gear at any one moment in time according to the cadence you're at, to avoid over-stressing the motor and potentially damaging it. A high-torque hub motor like a BPM paired with a 20a controller or higher will be able to climb the hills almost as well as a normal crank-drive setup, and in my view would be a better option unless you live in a very hilly area.

 

[Wingreen]

I've rode up Allt Goch Bach on my Big Bear more than once. It is definitely quite a steep hill. I live near Llandudno now and used to live in Bangor. Maybe you (Wingreen) and I will run into each other on our Big Bears sometime .

I think a crank motor is probably easier to fit than a rear hub motor. I would recommend your friend gets a local bike shop or mechanic to fit the kit for him unless he know exactly what he's doing. I'd agree with other posters that a front hub motor is prone to wheel spin, especially when going uphill on a wet day. A rear motor is definitely better I'd say.

My opinion on crank driven bikes is that they are less fun to ride than hub drives, and require more skill. Much more frequent gear changing is required on a crank drive, and it is necessary to be in the correct gear at any one moment in time according to the cadence you're at, to avoid over-stressing the motor and potentially damaging it. A high-torque hub motor like a BPM paired with a 20a controller or higher will be able to climb the hills almost as well as a normal crank-drive setup, and in my view would be a better option unless you live in a very hilly area.

Thanks John_S - again, very useful information (which I have already passed on to the person who is trying to decide on his best option).
Small world! Yes, we may yet still bump into each other (hopefully not literally!) on our Big Bears.
If you do come to this part of the world again, you might be interested in some of the (circular) routes I've planned around here. If so, here is the link (I hope!):

https://www.routeyou.com/en/group/view/7464/anglesey-and-nw-wales

By the way - not sure how you move your Big Bear around to different places but, if you have a tow bar, I can certainly recommend one of these:

http://www.halfords.com/cycling/bike-racks/towbar-mounted-bike-racks/exodus-2-bike-towbar-mounted-cycle-carrier

You do need to have a tow bar and it does look counter-intuitive - but it works (and less than £60)

 

[anotherkiwi]

I've rode up Allt Goch Bach on my Big Bear more than once. It is definitely quite a steep hill. I live near Llandudno now and used to live in Bangor. Maybe you (Wingreen) and I will run into each other on our Big Bears sometime .

I think a crank motor is probably easier to fit than a rear hub motor. I would recommend your friend gets a local bike shop or mechanic to fit the kit for him unless he know exactly what he's doing. I'd agree with other posters that a front hub motor is prone to wheel spin, especially when going uphill on a wet day. A rear motor is definitely better I'd say.

My opinion on crank driven bikes is that they are less fun to ride than hub drives, and require more skill. Much more frequent gear changing is required on a crank drive, and it is necessary to be in the correct gear at any one moment in time according to the cadence you're at, to avoid over-stressing the motor and potentially damaging it. A high-torque hub motor like a BPM paired with a 20a controller or higher will be able to climb the hills almost as well as a normal crank-drive setup, and in my view would be a better option unless you live in a very hilly area.

If you use your gears with a hub motor you get more range but it does allow you to be more lazy if you wish (gear changing lazy I mean).