Hello from Queensland. I'm an old fossil who's spent too much of his life two wheeled machines.

[vitabrick]

I decided a few months ago to build an e-bike using a pretty good second hand MTB as a base. It's been something of a trial. Just about everything has to be built and unbuilt a half dozen times to meet my exacting requirements. This is ongoing as everything has to work well and be as easy to service as I can make it. And I'm learning more about it all the time. Being a selfish sort of prick, I went for the biggest badest thing I could afford, which was a (supposedly) 1500W hub motor, with a 20A battery to match. My initial thought was, "Oh yeah, I'll definitely be wanting the hand throttle". On the first test, a couple of problems became apparent. Firstly, the pathetic MTB gearing runs out way before the motor runs out of legs. It's pointless even pretending to pedal, and attracts unwanted attention. Secondly, the power delivery is super abrupt. Full throttle is no more than 1/4 turn and the sensation is very much all or nothing. Feathering the throttle delicately requires virtually superhuman control. Thirdly, it's way too busy on the right grip. I've had to swivel the gear selector down to a really awkward angle in order to clear everything. Furthermore, since top gear is selected virtually all of the time, when you find that you have to pull up on a steep uphill, it's impossible to make the necessary downshifts before halting without dropping the throttle altogether. This is a really s*it sensation.

I'll try a freewheel with a 13 tooth top gear, and try fitting my road crankset to see if this is sufficient to solve the gearing problem, although a big chainring might not clear the stays. But really, I've had to reconsider the whole thing. The first thing I want to try out is the PAS system in order to tame the power delivery somewhat. I could limit the output to 250W by simply joining a pair of wires provided for the purpose. I'm not sure if connecting the PAS has the same effect. Guess I'll find that out soon enough. On the plus side, it would serve the purpose for which it was intended, to make cycling easier. On the other hand, sometimes I just enjoy going like stink. But doing this makes it blatantly obvious that it's really a motorised vehicle, so I'm preparing it for actual registration. Doing this might help me out in the event of a stack too.

What I'm thinking that I'd like to try, if it's possible, is to fit the PAS while retaining either the twist, or fitting a thumb throttle. I'd like it to be either tame or wild as required. 250W might be OK if that's all you've got. But leaving the best part of what's available on the floor doesn't have a lot of appeal. Any useful advice in this regard would be appreciated.

 

[Stefan Mikes]

Any useful advice in this regard would be appreciated.

Go buy yourself a decent manufactured e-bike?
We've got several Australians here who have actually done it.

 

[Dallant]

I decided a few months ago to build an e-bike using a pretty good second hand MTB as a base. It's been something of a trial. Just about everything has to be built and unbuilt a half dozen times to meet my exacting requirements. This is ongoing as everything has to work well and be as easy to service as I can make it. And I'm learning more about it all the time. Being a selfish sort of prick, I went for the biggest badest thing I could afford, which was a (supposedly) 1500W hub motor, with a 20A battery to match. My initial thought was, "Oh yeah, I'll definitely be wanting the hand throttle". On the first test, a couple of problems became apparent. Firstly, the pathetic MTB gearing runs out way before the motor runs out of legs. It's pointless even pretending to pedal, and attracts unwanted attention. Secondly, the power delivery is super abrupt. Full throttle is no more than 1/4 turn and the sensation is very much all or nothing. Feathering the throttle delicately requires virtually superhuman control. Thirdly, it's way too busy on the right grip. I've had to swivel the gear selector down to a really awkward angle in order to clear everything. Furthermore, since top gear is selected virtually all of the time, when you find that you have to pull up on a steep uphill, it's impossible to make the necessary downshifts before halting without dropping the throttle altogether. This is a really s*it sensation.

I'll try a freewheel with a 13 tooth top gear, and try fitting my road crankset to see if this is sufficient to solve the gearing problem, although a big chainring might not clear the stays. But really, I've had to reconsider the whole thing. The first thing I want to try out is the PAS system in order to tame the power delivery somewhat. I could limit the output to 250W by simply joining a pair of wires provided for the purpose. I'm not sure if connecting the PAS has the same effect. Guess I'll find that out soon enough. On the plus side, it would serve the purpose for which it was intended, to make cycling easier. On the other hand, sometimes I just enjoy going like stink. But doing this makes it blatantly obvious that it's really a motorised vehicle, so I'm preparing it for actual registration. Doing this might help me out in the event of a stack too.

What I'm thinking that I'd like to try, if it's possible, is to fit the PAS while retaining either the twist, or fitting a thumb throttle. I'd like it to be either tame or wild as required. 250W might be OK if that's all you've got. But leaving the best part of what's available on the floor doesn't have a lot of appeal. Any useful advice in this regard would be appreciated.

As an old fossil, aren’t you wasting time? Do you want to ride or build machines that don’t work?

 

[indianajo]

Welcome to the site.
I understand the store bought bikes in Aust are particularly wimpy. 250 W was it? No hills in Australia? I cross 80 of them weekly to my summer camp, twice. I carry 60-80 lb of groceries or ag supplies on the uphill outbound leg.
I've had 3 hub motors, & 3 throttles, none has has the abrupt power on action you complain about. 1000 W direct drive motor (didn't like the drag unpowered, couldn't find a 32-13 freewheel to fit it). 1300 W ebikeling geared hub motor (wore out gears ~4500 miles) Mac12T 1000 W geared hub motor (2000 miles, burned wire harness pin off in the rain 2 weeks ago, clutch make the fork shudder when engaging). The PAS on the ebikeling was too jerky, 500 W minimum acceleration and minimum speed 11 mph which would throw me off if I hit a rut on Ste Rd 3. I deleted PAS pickup, and only use throttle when I use power. You might try a different throttle, they only cost about $12. Different controllers are about $40. I'm waiting on a new one, directimports of the USA apparently shipped it by barge from Timbuctu. Ordered 7/14, it's 7/27 and no sign of a controller.
My self electrified bike came with a triple front and 8 speed rear sprockets. 32-42-52 front, 11 to 32 on the rear. I can ride 1 mph up hills without power if I want to, and can keep up with the motor @ 25 mph. On an unsuspended bike I really don't want to go more than that as potholes are deadly at that speed. Where pavement is perfect and gravel is not, I do peak at 35 mph at the bottom of some of my hills.
At the lower speeds of a bicycle, look around and enjoy the scenery some. Speed isn't everything. If it is to you, gasoline is your elixer. Enjoy the resultant fires, floods, heat waves, late spring freezes.

 

[vitabrick]

Go buy yourself a decent manufactured e-bike?
We've got several Australians here who have actually done it.

Maybe I will, but hell, it's only my first dabble, and building one myself seemed at first glance to be an economical way to do it. And it probably is, everything considered. The initial purpose was simply to have a light machine to nick down to the shops on. I live in a particularly hilly area and my touring and racing days are well behind me. And I've always built or modified bikes. There's always some sort of compromise to be made.

 

[vitabrick]

As an old fossil, aren’t you wasting time? Do you want to ride or build machines that don’t work?

Maybe, but I don't think so. It works, straight up. The aim is to have it working to my satisfaction. And if that's not achievable then at least I'll have learnt a fair bit. I've owned the same highly modified BMW for over half my life now. And I know just about every nut and bolt in the thing. I meet guys all the time who've bought big shiny new things, but you know, most of the time I can visualise them in the knackers yard in just a few short years. And they ride a lot more than me too. In big weekend packs, Harleys to the front, then Jap cruisers, other European bikes, with sports bikes bringing up the rear. And they wave to everyone else on a bike. "Look, I'm part of the "brotherhood", I've purchased an entire image", Yeah, whatever. Hardly a one of them could make a repair worth a damn. Where are all of the infinitely repairable old Harleys? I'm sure that there's a wealth of information to be mined at this site, but I won't find it without sieving through a fair old load of mullock.

 

[vitabrick]

Welcome to the site.
I understand the store bought bikes in Aust are particularly wimpy. 250 W was it? No hills in Australia? I cross 80 of them weekly to my summer camp, twice. I carry 60-80 lb of groceries or ag supplies on the uphill outbound leg.
I've had 3 hub motors, & 3 throttles, none has has the abrupt power on action you complain about. 1000 W direct drive motor (didn't like the drag unpowered, couldn't find a 32-13 freewheel to fit it). 1300 W ebikeling geared hub motor (wore out gears ~4500 miles) Mac12T 1000 W geared hub motor (2000 miles, burned wire harness pin off in the rain 2 weeks ago, clutch make the fork shudder when engaging). The PAS on the ebikeling was too jerky, 500 W minimum acceleration and minimum speed 11 mph which would throw me off if I hit a rut on Ste Rd 3. I deleted PAS pickup, and only use throttle when I use power. You might try a different throttle, they only cost about $12. Different controllers are about $40. I'm waiting on a new one, directimports of the USA apparently shipped it by barge from Timbuctu. Ordered 7/14, it's 7/27 and no sign of a controller.
My self electrified bike came with a triple front and 8 speed rear sprockets. 32-42-52 front, 11 to 32 on the rear. I can ride 1 mph up hills without power if I want to, and can keep up with the motor @ 25 mph. On an unsuspended bike I really don't want to go more than that as potholes are deadly at that speed. Where pavement is perfect and gravel is not, I do peak at 35 mph at the bottom of some of my hills.
At the lower speeds of a bicycle, look around and enjoy the scenery some. Speed isn't everything. If it is to you, gasoline is your elixer. Enjoy the resultant fires, floods, heat waves, late spring freezes.

Thanks for this reply. It's informative. That 13-32 you mentioned seems to be the only 8 speed screw on which specifies the minimum possible number. As far as speed goes, I cut my teeth in a pretty aggressive environment. The bad effects of this could only be minimised by travelling as nearly as possible to the speed of the traffic around me. This naturally led to racing. Touring by bicycle, on the other hand, allows for experiences totally missed by most other travelers.

Have you had PAS which worked well? Many seem to swear by it. Maybe it's only good at modest power output. I'd appreciate your thoughts on the possibility of mixing inputs. The discussions I've found on throttles are not specific enough on the points I'm interested in. Primarily, I'd like the ramp from min to max to be gentle and progressive. I haven't explored the world of controllers so far, so have not much of an idea as to what different ones might have to offer. I expect that my solution will be found in the combination of the two.