Counter shaft sprockets?

[Trials bike]

Hi,
Where can I find front sprockets for the golden motor that are for 520 chains? I've searched but have no luck.

I'm going to convert an old gasgas trials bike to electric.

Thanks

[Bikemad]

It would help if you stated which motor you need the sprocket for, as the shaft sizes are different:

• The shaft diameter on the 3kW motor is 20mm with a 5mm wide keyway.
• The shaft diameter on the 5kW motor is 22.2mm (7/8") with a 5mm wide keyway.
• The shaft diameter on the 10kW motor is 25.4mm (1") with a 8mm wide keyway.
• The shaft diameter on the 20kW motor is 30mm with a 8mm wide keyway.

I have already given you some useful information in my initial reply to your previous post based on the assumption that you might be considering the 5kW BLDC motor like they have fitted in this trials bike:



The Electro-Motion trials bike uses a two stage gear reduction. 
The primary stage is via a toothed drive belt and the secondary is via the chain:


The primary belt reduction ratio appears to be 2:1, and the sprocket gear ratio appears to be ~6.45:1 (9T:58T):


This produces a combined total gear reduction of ~12.9:1.

To obtain the same gear reduction (and torque multiplication) using a single stage chain drive setup, a front 10 tooth motor sprocket would require a rear sprocket with 129 teeth, which would have an outside diameter of almost 26" (66cm) with the correct 5/8" (0.625") tooth pitch for a 520 chain. 

Alan
 

[Trials bike]

Wow, thanks for all of that!

The belt driven gear reduction system is completely beyond me. Unless there is a kit that I can bolt on this isn't going to happen. Is there a kit?

You're saying that ill need a rear sprocket that is larger than the rear wheel on the bike... thats not going to make for a good trials bike.

Yes, the 5kw motor is the one I am interested in.

[Bikemad]

I don't suppose that Electro-Motion will want to sell a complete primary drive mechanism as it is not for their bike, and it is unlikely to simply bolt straight on to your bike, and would probably be very expensive too.

Without the primary reduction, you would need to go as large as possible on the rear sprocket to provide the best possible torque from a single reduction setup, and you might have to use a custom made sprocket to obtain the required size, as I don't suppose there are many standard ones available with such a large number of teeth.

I was just looking at sprocketspecialists.com and the largest sprocket they list is 74 teeth, which would give a reasonable reduction of 7.4:1 with a 10 tooth front sprocket.
It might be worth sending an email, asking them if they would be able to make an even larger one. 

Compared to the double reduction setup, the available torque at the wheel would be reduced by around 22%, but this should also increase the top speed from 34mph to just over 40mph (assuming you have a similar sized rear tyre to the one shown used on the Electro-Motion bike). 

Having said that, the actual torque produced by the motor will also be directly proportional to the amount of current that the batteries and controller can deliver to the motor.
Unfortunately, I don't know which make or model of controller is used on the Electro-Motion bike, but I did find the following useful information while I was looking:

• At the flick of a switch the power is that of a conventional 125, 250 or 300 moto trials bike,
• In muddy conditions, at the flick of a handlebar switch the power can be reduced,
• Zero Pollution,
• No fire risk if riding off road in high fire season,
• No kick starting, just turn on the power and go,
• No gear changing to worry about,
• No need to use a clutch,
• No engine noise,
• Virtually no maintenance,
• Neighbour friendly,
• When going downhill the recharge button allows the battery to be replenished.

• Frame: Chromo Steel perimeter,
• Weight: 75 kg Wet!,
• Front Suspension: Olle Hydraulic,
• Rear Suspension: Olle adjustable shock
• Front Brake: AJP 4 piston hydraulic
• Rear Brake: AJP 2 piston hydraulic
• Rims: Morad 1,6’’x21’’ & 2,15’’x18’’ tubeless
• Tyres: Maxxis
• Power Train: Brushless DC Electric Motor,
• Power: 5KW nominal (approx. 10KW peak),
• Torque: 16Nm nominal (approx. 20Nm peak),
• Mapping Available (4): Novice, Trek, Wet Trial, Dry Trial,
• Primary Drive: Toothed Belt,
• Secondary Drive: Chain,
• Maximum Speed: 34mph,
• Time Range: 60-160 minutes,
• Power Source: 51.8 volt 25ah,
• Lithium Polymer Battery,
• Charging Time (10amp Charger): 150mins for a full charge
• Number of Guaranteed Cycles: 1000 cycles.

Alan
 

[Dwcrigler]

You can find high quality prockets to fit the Golden Motor 5KW BLDC and 10KW BLDC at Amp Sprockets website. I've tested all of these and the work really well. They are hardened steel and have a galvanized coating to resist rust:

https://www.ampsprockets.com/shop/amp-sprockets-golden-motor-10kw-bldc-model-hpm-10kw
https://www.ampsprockets.com/shop/amp-sprockets-golden-motor-5kw-bldc-model-hpm5000b