901 on recumbent tandem

[ezbikin]

Hi all,

     We have a RANS Screamer recumbent tandem with a 350w system, and are considering upgrading to the 750w 901 kit. Wondered if anyone has dealt with similar projects? The issues I can see are (1) the length of wires that go from the rear of the bike where battery will be located, and the handlebars. Our present set-up requires a 126" wire. Pedelec wire also needs to be longer I believe, as the stoker crankset is further away from the motor/battery location than in most bikes. (2) Dropout width is 145mm. My instincts tell me that I should be able to use a 7/8 speed freewheel, given the additional width. Anyone have any thoughts? I'd appreciate hearing from anyone with experience on an installation like this, and any other issues they ran into. Thanks
Jim

[Bikemad]

Hi andto the forum Jim, I presume your tandem is similar to this:



As you already have twice the normal pedal power going to the rear wheel, have you considered using a front hubmotor instead of the rear one?

This would mean your existing gear arrangement could stay exactly as it is, and all the control wires should be long enough to reach, and it would give a better weight distribution as well.
The battery supply lead would need to be slightly longer than normal, but the main advantage with driving the front wheel would be greater torque for hill climbing due to the much smaller wheel.

A few more details might help with the decision making process:

• Does it have steel or aluminium forks?
   
• Are you looking for more speed or greater assistance on hills?
   
• Do you have disc brakes or the standard rim ("V") brakes?
   
• What would be the typical weight with two riders & luggage etc.?
   
• Do you have a rack/ panniers suitable to carry the battery?
   
• Is there a convenient place to mount the speed controller?
   

That should at least give you something to think about.

Alan
 

 

[ezbikin]

Thanks for the reply Bikemad. The bike is all steel, rim brakes on front and rear, with a rear disc drag brake for the stoker. The usual additional weight is about 425 lbs. We have a good rack set-up for the current system, sliding the battery right onto the hook-up on the rack. There would appear to be plenty of room between the tire/fender, and the rack for controller mounting. As we're looking for a little additional climbing ability, I have considered the front motor, but space at the front of the machine is at a premium for mounting anything other than the wheel, and I'm concerned the front motor wheel would make the handling a little more squirrelly than it already is. That, and having used the current system on one tandem or another for three years, I've solved all the problems we've encountered  with a rear motor wheel. There is one other safety consideration. The captain's position is configured like  short-wheelbase single machine, and they all have an inherent heel-strike consideration with cornering. It's bad enough with just pedal power, but I would think it could cause injury with power to the front wheel.
     on the GM website I have seen a rack with the controller box mounted to the bottom of the rack. Is that an option?
Looking forward to any other of your thoughts.
Jim 

[PEDAL IN POWER OUT]

hi ez
I am working on a front drive bike with the 1000 watt motor pictured.
All components are Golden Motor.
The battery is mounted midship with the bracket shown.
The bracket has saddles to allow it to sit level on the frame.
There is a 'glass board cut to mount the controller box below the battery bracket.
The picture of the battery tray in the frame shows the controller box with all of the wiring sitting on the floor, below the point where it would mount. Before the battery tray was welded these parts were fit to clear the chain. I do not know how much chain slap contact there will be until it is ridden.
This tray is powder coated steel scrap. If it works on the road, the design will be redone in brazed aluminum, and coated to match the frame color.
I must apologize for having no pedelec experience. In this install the crank is very close to the controller.  
I hope the pictures upload. If they dont, I will try to repost. I am sure what I described wont make sense without the pictures!

[Hardcore]

I don't think PAS will be a good idea, I think using the thumb throttle or so to get the assist you want. Pas only has one level and that's full speed.

[ezbikin]

     Regarding the PAS level, the website has the programming for the new PC interface, and it shows low, Mid, and high levels of PAS to be entered into the controller. Or am I misunderstanding it. I'm not the most computer literate guy out there! I've not used a GM set-up or even seen one, so I'm just making educated guesses on some of this stuff. My idea would be to program it for low assistance and then have the thumb throttle available for bursts/hills. Is that possible with the new controller interface? Thanks.
Jim

[PEDAL IN POWER OUT]

Hi ez,
I am learning about this pedelec situation.
It  did not sink in until I read hardcore's post that pedelec go mode was one fixed speed.
I can confirm what you have gleaned from the parameter control screen. There is a selection for 3 levels of the pedaling assist, but the software cannot be run while the controller is running. At least not with the stock wiring. I know I wouldn't want to be flying down the road on a bike that has a controller in the middle of sorting out what it is supposed to do.  I should start working on a laptop mounting bracket for the handle bars. I think I know where this is heading.

I am sure I will be shot out of the water on this idea, but if it was me, and I was determined to have a pedelec system I would have a toggle switch to CANCEL Pedelec on the fly. Then the remaining question is if the variable throttle would take control.

The way better idea is to use the cruise control instead of pedelec. Pedelec is only 1 fixed speed. The variable cruise control speed setting seems much more useful. Like hardcore said, you need a variable throttle.

[ezbikin]

     Great thought on the handlebar mount for the laptop! Seriously, my thinking on the PAS is that most non-geared wheel motors, including our current Bionx, have some drag when not in assist mode, so I  figured I could set the system on low to begin with, in order to overcome the drag, and then use the thumb throttle, or the suggested cruise control at other times. Low may be too low and I would maybe have to try other levels, but that would be my starting point. Generally PAS gives more assistance when pedaling faster, for example I can leave the Bionx on assist level 1 and climb just about any hill using the 26 tooth chainring, and fifth/sixth gear on the freewheel, but should I shift up to the 38 tooth chainring, I lose most of the torque, even if I shift the freewheel down to the equivalent gear inches to the 26. There is no saying how the GM system works without trying it of course. Thanks.
Jim 

[Bikemad]

Sorry to jump in so late on the PAS conversation, but I've just finished work and had a quick bite to eat and now I'm trying to catch up.

The pedal assist is variable and is definitely not a fixed speed, if you slip the chain off and raise the wheel off the ground you can clearly see it is somewhat linked to the chainwheel speed.

In my opinion the PAS does have some negative aspects;

• The assistance seems to be too great for the actual pedalling speed, which presumably accounts for the two previous comments stating "Pas only has one level and that's full speed" and "Pedelec is only 1 fixed speed".
  
• While in pedal assist mode, the throttle is disabled until you actually stop pedalling for a few seconds, so you cannot simply apply more power when required.
  
• Mine also appears to have a mind of it's own and will only work when it feels like it.
  

I want to put a switch on my PAS, so I sent an email to Tom over a month ago, asking whether to put the switch into the signal wire or the 5V feed wire, and I'm still waiting for a reply.
As I don't want to start chopping my wiring in the wrong place, I've simply unplugged it for the time being, so I don't yet know whether there will still be a few seconds delay on the throttle reactivation when you manually turn off the PAS.

If it was possible to select a lower PAS setting, without it disabling the throttle and have it work consistently, I would be much happier with it.

Looking on the positive side, the way it currently works (when it's not on strike) presumably complies with the law, and this is the main reason why I still want to use it.

Alan
 

[ezbikin]

Thanks for the input Alan. May I ask, is your system set up using the new interface? I have the PAS on present systems first of all because it is a part of the proprietary system, it's legal, and lastly, I like being able to use the system in a manner where I try to see  how many miles I can get out of a charge, rather than just using the thumb throttle to avoid pedaling. I originally got the system when I had knee issues. Now that both knees have been replaced, I still like to use it, but not as much.
Jim

[Rafa]

As I have seen with PAS and my 1 Kw hubmotor, PAS always run at 100% of power. I had mounted both PAS and tumb throttle and neither of those work together well. Finally I dismount the PAS and use trhottle and cruise botton to regulate the power.

[pixelplay]

i have PAS setup on my bike with the magicpie and find it quite good. it does give the feeling of running at full speed when you keep peddling but this is because the speed picks up very quickly as the motor assists you. I have my bike set in the top gears and just use the two very top gears even on hills and find that this way it works well for me. I also have a thumb control and I use the thumb control to get off the traffic lights quickly or to get going and then I start peddling. This mean I am mostly travelling fast on my bike and if I want to go slower I just pedal a bit and then stop and the motor kicks in for a few seconds and then stops this usually works good enough.

I am considering adding a switch into the system so I can quickly disable the pedelec because at times it would be good to just pedal and not have the motor kick in at all. I will add a switch early next week an let everybody know how it works out for me, and of course add some info on how to do it.