a couple more quick newbie questions

[Andrew]

Do the the Lithium batteries i.e 48v 12AH get hot?  Is it ok to cover them, for instance in or under a rear rack panieer?

Are the Lithium batteries different weights? is there a difference in weight between 36v and 48v batteries? or is the weight difference more in the  AH rating of the battery??  

Lastly what would be the difference in performance on a Magic Pie motor between the 48v12ah and 36v16ah ?

As you probably can tell I know very little about rechargable batteries  

Cheers
Again
Andrew

[GM Brazil]

Hello Andrew,

From my experience in Brazil (25ºC to 35ºC) the battery gets only warm outside. I do not leave the bike under the direct sun while locked or in someplace that can rain. I used the bike several times during rain to test and was ok, just dry the bike and battery and leave it vertically to dry inside. Do not turn it on if the bike was parked under direct rain.

There are different weights for the batteries:

LFP4812= 6,5 kg
LFP3616= 6,7 kg
LFP3612= 6 kg
LFP2416= 5,5
Frog 36 and Frog 24 = ?


The Magic Pie with the 4812 will have 20/25kg range and 40 to 45km/h max speed. With the 3616 you will have 34 km range and the max speed is 35km/h.

The batteries are made of LiMn and have an internal BMS (Battery Management System) that protects the battery from over loading, low voltage and it does the balance between cells during charge. It is better to charge up after every ride to max the life span.

[Andrew]

thanks very much for your detailed and thorough reply  

I'm currently trying to decide what battery to order with my MP kit so the information is really useful.  As for covering the  battery, we don't get too much hot bright sunshine here in Wales UK, but we do get lots of rain. the reason for wanting to cover the battery is more to do with keeping the bike looking discrete and 'push bike' like rather than motor driven, so I thought I may bebe able to modify a panieer, or at least drape a double panieer bag over the battery on the rear rack.  

What would your choice of battery be for a MP?

Andrew

[Bikemad]

The reason for wanting to cover the battery is more to do with keeping the bike looking discrete and 'push bike' like rather than motor driven, so I thought I may bebe able to modify a panieer, or at least drape a double panieer bag over the battery on the rear rack. 

Hi Andrew, hiding the battery is the easy bit, but hiding a Magic Pie will be an entirely different challenge!
I use a home made Lithium Polymer (LiPo) pack tucked inside the R/H panier:



However, LiPo's are not very safe and I strongly recommend that you don't use them, unless you fully understand the risks involved with both charging and use.

The GM LiMn (Lithium Manganese) packs are very safe and much more user friendly when it comes to charging and general use.

What would your choice of battery be for a MP?

If you require more speed, then the 48 volt pack is better, but if you are looking for a long range, you might be better to opt for a 36 volt higher capacity (16Ah) pack.

The 24 volt pack should give you a legal top speed of around 15mph with a 26" Magic Pie, whereas the 36 and 48 volt packs would give a top speed of approximately 20 and 25mph respectively, but the maximum speed can be reduced (to comply with the 15mph legal limit) at the flick of a switch, by modifying the throttle as shown here:



Alan
 

[Andrew]

Thanks Alan,  your reply is like music to my ears. You've given me all the answers I could have wished for,,, especially with the speed limiting switch  

From the diagram above what parts would I have to source myself to do this 'mod'?

Also, with  the MP software, I understand you can tailor the motors performance and change the voltage from 24 to 36 to 48. Will this have much of an effect, and can these changes limit top speed?

More newbie questions....  
would mounting the MP on the front wheel be a good or bad idea. The reason I ask is that i'm worried about the overall weight on the back wheel and tyre, and that I may have to completely change my 9 cog cassette. It would be nice in theory to keep the rear drive for pedaling when the motor is limited for road use.

and if using a rear wheel MP... what tyre and innertube is advisable to avoid puncture due to extra load weight

Andrew

[Bikemad]

From the diagram above what parts would I have to source myself to do this 'mod'?

I have shown an adjustable Potentiometer instead of another trim pot so that you can easily adjust the maximum speed whilst riding and set it exactly where you want it.
This could be replaced with a second trim pot if required, or if a two way switch is used, it could even be used in addition to it.
This would give you the option of switching between a pre-set legal maximum speed setting and a user adjustable maximum speed which could be adjusted anywhere between "snail mode" and unrestricted.

You would need a diode, 4.7K Ohm resistor and 2 x 5K Ohm trim pot (or 1 x trim pot and 1 x Potentiometer)

You could use the light switch on the throttle unit to switch between limited and unlimited throttle, but it might be better to have a hidden switch mounted out of sight (but within easy reach).

Here are a few links to some suitable components I found on eBay:

10 x 1N4148 Diodes
10 x 4.7K Ohm 0.25w Carbon Resistors 1/4w Resistor
10 x 5K Ohm Precision 3296 Variable Resistors Trim Pot
3 x 5K Ohm Preset Variable Resistors
5 x Linear Potentiometer 5K Ohm
1 x Sub-Miniature 2 Way Toggle Switch (SPDT)

Also, with  the MP software, I understand you can tailor the motors performance and change the voltage from 24 to 36 to 48. Will this have much of an effect, and can these changes limit top speed?

As I don't have one of these I don't actually know what difference it will make. Others who have used it, noticed a difference in performance when the voltage was changed. Perhaps someone could give some detailed information about their experience with some of the different settings.

More newbie questions....  
would mounting the MP on the front wheel be a good or bad idea. The reason I ask is that i'm worried about the overall weight on the back wheel and tyre, and that I may have to completely change my 9 cog cassette. It would be nice in theory to keep the rear drive for pedaling when the motor is limited for road use.

and if using a rear wheel MP... what tyre and innertube is advisable to avoid puncture due to extra load weight

Front Magic Pies can be used as long as you have steel and not aluminium forks, but a torque arm would be advisable to help take the load off the dropouts.

The weight on the rear is not really a problem, it's probably less than a child in a child seat mounted on the back of your bike.

As far as tyres are concerned, if you can fit a slightly wider/deeper tyre, it would help to improve the ride, but the standard tyres should be fine if they are kept at the correct pressure. If you're really concerned about punctures, you might want to try puncture-proof tyres instead of pneumatic ones.

Alan
 

[Andrew]

fantastic Alan,   I'm not sure i'd be comfortable at the moment creating a switchable power limiter myself, perhaps someone in the Cardiff area could give me a hand when the time comes, but it is great to think it can be done and could even be done through the light switch on the throttle if not a hidden switch.

You've convinced me to go rear wheel drive with the MP and I suppose better traction will be had from the rear too.

As you can probably tell I have all the usual 'apprehensive' questions about a product I have yet to see first hand. I'm a little worried about the pedalling action becomig redundant and would like the possibilty of getting some gentle exercise still from the bike at times!   Is this feesable? if so I cannot imagine needing many gears if 'assisted' by the motor?  what's your take on this, any ideas? and is the bike still rideable with motor swithed off?

You've been most helpful Alan,


Andrew


By the way, i'm looking to make my order to China in the next few days

[Bikemad]

Andrew,

You can pedal as little or as much as you like, you simply use the throttle to control the level of assistance rather than your speed, or set the cruise control slightly below your desired speed and see if you can provide enough pedal power to maintain a slightly higher speed than the motor. If you want more exercise, you will just have to try and use less throttle, which is not quite as easy as you think, because it takes a lot of self control not to use all the motor power that is available! (But maybe that's just me.)

There are a lot of hills where I ride my bike, but my bike spends most of its time in the highest gear. When I come to a steep hill, I usually stand up, pedal harder and climb it much faster.

You certainly won't need a nine speed freewheel on a Pie, although they have been fitted:


Alan
 

[Andrew]

ok once again i've received all the answers I was hoping to hear. I'm looking at purchasing the kit on Tuesday from GM in China.  I currently have a 9 cog cassette on my mountain bike but have decided to purchase a 6 cog from GM and also a rear disc brake set as my bike frame has the mounting brackets ready for the disc caliper

I'll probably have more questions to come (no doubt), but just for now.....   how long did your kit take to reach you in the UK , that is if you used air shipping or even purchased it from abroad,, and most importantly how much duty and tax etc did customs fleece you for?  or do you have any idea what it's likely to be?

Cheers
Alan

Rgds

Andrew

[Bikemad]

Andrew, I had to wait much longer for mine to become available than it took to to be delivered, due to an unexpectedly high demand at the launch of the Pie!
I guess it must have taken nearly a couple of weeks to be air shipped from China once it was finally sent, and luckily for me, no import duties were requested on my wheel kit, so I have no idea how much you might be asked for if you're unfortunate enough to have to pay it.

Alan
 

[Andrew]

Thanks Alan,   
yes it does seem to be a bit of  hit or miss with customs,, but i'm prepared for the worst.

Have you by any chance had to deal with GM since ownership?  if so, how have you found their customer service and communication. I have read articles on other forums where GM employees have seemed quite active.

[Bikemad]

My main dealings with GM (apart from forum moderation) has involved suggestions to improve a couple of obvious design problems that I (and a few other forum members) had noticed with the early Magic Pies. These suggestions were immediately taken on board by GM who quickly implemented changes to the manufacturing process in order to eliminate these problems. This resulted in the modified hub and new spoke pattern on the built up Magic Pies that are currently being produced, along with correct centring of the rim on the new 20" cast aluminium Magic Pies.

The guys at GM can be very busy at times, which can unfortunately results in delayed responses to emails concerning technical queries and warranty problems. It would make a big difference to customers if GM could find some means of actually reducing the email response time to a more acceptable level.

Alan
 

[Sundsvall]

Alan (Bikemad) is one of the main reasons why this forum is such a great place. Despite the fact that GM doesn’t have a functional customer support, they did implement those suggestions from Alan immediately. It means that somebody from GM do read this forum.

An advantage to shop inside the EU is that there’re no additional taxes. I’ve ordered things from around the world and only a few times had to pay custom duty. But when they ask for payment evidence, it’s great to have an order payment from the same company with a lower price.

Peter

[Andrew]

well i've made the decision to purchase the pie kit from China, but I will be sourcing other bits I need from the UK, because once you add on extras onto your kit order the shipping rises to the point of not being ecomonical.

I have a very good quality mountain bike for the kit,  it has v-brakes at present but the frame has been designed for a disc brake set-up.  Would it be necessary to upgrade the rear brake to a cable driven disc set-up as the MP will be on the rear and has the convenience of having a disc friendly hub?

Another random question....,  what would be the widest tyre you could fit to the 26" MP rim?

[Sundsvall]

My frame doesn’t have brackets for a disc brake calliper but I’m going to convert it anyway. The main reason is that I changed the rim to a wider one as my rear tyre is 75 mm and the rim isn’t made for v-brakes. If the frame had these brackets I would convert it even if the rim could handle v-brakes because I think the disc brake is superior. So my advice is to convert to disc brakes but there’s as always a question of cost.

The rim from GM has an outer width of 25 mm on which you can fit a 40-50 mm wide tyre on.

Peter