Polini Motor: Mechanical design and Reliability

[Spiff]

There is a new ebike motor Polini E-P3+MX, which is manufactured in Italy and has good characteristics, and what is best, this motor has preventive maintenance and is repairable:

Polini E-P3+ Motor

Regarding the specifications, it offers high power and torque and also large batteries

• 600W Maximum Power
• 90 N-m Torque
• Has a grease port for preventive maintenance
• Manufacturer sells spare parts for repairing.

There are a couple of Youtube videos that show the motor internals and also the manufacturing plant:

But after watching the videos, I can see that the internal mechanical design is simpler and different to Bosch and Shimano motors, and as I am not an expert, I´d like to hear the opinions from the mechanical experts:

• Polini Motor has a small motor gear that engages directly to a large gear wheel, this is used to reduce the high motor RPM to the lower rider cadence. But in Shimano and Bosch motors, this RPM reduction is done using several stages of gear cogs, which is more complex but I suspects it should have also some benefit.
• Polini motor has "Straight" cogs while Shimano and Bosch use "Helicoidal" cogs
• Polini Motor has a clutch to engage and disengage motor to cranks, this is made by means of a ratchet with three pawls (same has real wheel freehub), while Shimano has two clutches of type Sprage Roller which has many rollers inside, and Bosch has a similar design.
• Polini motor does not use bearings for the Bottom Bracket, they use bushings, and they say that this provides a better sealing, although the friction and wear should be higher than in bearings. Shimano and Bosch use bearings

I am attaching a few captures from a Polini video and also a Shimano motor:

Shimano motor for comparison.

 

[Zimmerframe]

@knut7 did a review on the motor a while back :

Article - Polini E-P3+ motor review

We finally got our hands on the Polini E-P3+ emtb motor, rated at 75 Nm. There’s also a more powerful Polini E-P3+ MX. The specs of both motors are identical, except for the MX-version being rated at 90 Nm. Here are all the brands using Polini motors. We rode a Focarini Ultra. Polini E-P3+...

www.emtbforums.com

There was also a thread @Rob Rides EMTB started about the Fulgar Mula which has the Polini Motor.

Fulgur Mula, 20KG Full Fat ebike

Interesting bike I saw today at Berkshire Cycles. By Fulgur, an Italian brand: 20KG listed weight • Full Fat 90Nm motor by Polini - 160mm @extremeshox ERA Fork - 160mm rear travel with @extremeshox Storia Coil V3 - Modular internal battery 504Wh and you can add another 125Wh internal extender...

www.emtbforums.com

I believe @cappuccino34 was running one of these so he might be able to give you some feedback.

On the technical side, maybe @Bearing Man - but then he might not have seen inside one.

 

[Spiff]

Yes, I already saw some reviews of bikes and moto, but I am also interested in the opinions about the motor design approach and long term results, and although @Bearing Man might not have seen a real one, he might have an opinion about the design and expected reliability.

 

[Bearing Man]

On the technical side, maybe @Bearing Man - but then he might not have seen inside one.

Yes, I already saw some reviews of bikes and moto, but I am also interested in the opinions about the motor design approach and long term results, and although @Bearing Man might not have seen a real one, he might have an opinion about the design and expected reliability.

Sorry guys, I have not seen one yet. One of the few I haven't! However, I have heard good things, and the fact that I haven't been contacted by anyone asking if we can repair one, is usually a good sign!

 

[Bearing Man]

Bushing would be fine on the main crank shaft if there was user grease nipples or some form of user lubrication available otherwise im sceptical coming from an engineering and automotive background .

Yamaha use bushes and the grease is starting to go after around 1,500 miles, then the bronze bushes start to wear themselves and the crankshaft. So I would agree that unreachable bushing is not really the best way to go.

 

[Spiff]

Polini motor has a grease nipple, but I believe it is intended to grease the main large gear wheel. Grease may alro reach the right side crankshaft bushing but I am not so sure about the left side one.

 

[cappuccino34]

FYI, the Polini EP3+ has already been around for six years, so if there were any particular design issues with bearings they'd have been updated by now. I was also told that they have had ZERO failures so far, but I did point out that as yet they hadn't been testing them in soggy Rossendale millstone grit and mud bogs.

So far mine has been faultless. It's got similar output performance to my Bosch bikes and is also similar with regards to battery consumption. It's maybe just a little noisier than the Bosch, but nothing like as noisy as my Giant.

When the motor is off, or beyond the speed limit, it's very easy to pedal, so much so that in lower power settings I often don't even notice that it's no longer assisting because it nicely 'blends' away over about 1mph.

The display and configurability of power settings on the Polini is by far the best of the bikes we have in our family; which includes early Bosch CX4 kiox, Bosch CX4 smart, giant Yamaha and Spesh SL.

To be fair I haven't messed with the Bosch Smart app much because the Smart equipped bike is our eldest son's and he's got the app on his phone. Stupidly, you can only pair one phone to the bike, so I would have to take his phone to do anything on the electric side of the bike, which doesn't seem to smart at all to me.

One thing that the Polini doesn't (yet) do is transmit riding data (Speed, Cadence, Power) to external devices other than the phone app. I haven't tried recording rides with it connected to see if the data migrates because I don't use my phone to record rides; I have a nav that does that job because the rides I do tend to be longer than the battery on my phone will last whilst also playing music and doing the other phone stuff.

Hopefully a firmware update will enable connection to other devices like my nav or my watch.

 

[Spiff]

@cappuccino34 when you perform maintenance, is it possible to add grease to both crankshaft bushings?

 

[jimbob]

Is this motor compatible with any existing bike frames which were designed for other motors?

 

[cappuccino34]

@cappuccino34 when you perform maintenance, is it possible to add grease to both crankshaft bushings?

The grease goes on the drive gear. The main shaft is on sealed cartridge beaings, not bushings.

There may be bushes between the crank shaft and the drive hub but those parts only rotate against each other when you back pedal or when the motor overruns. Yamaha motors are on bushes in that position (except on mine, which had excessive play and noise form day 1 because the bushes were slack on the shaft, so I replaced them with needle roller bearings). The other motors may have bushes there too. I wouldn't be surprised because bushes are good for a heavy load, low speed, low rotation application.

 

[cappuccino34]

Is this motor compatible with any existing bike frames which were designed for other motors?

I'm not aware that the mounts are the same as any other, but you also have to consider the battery mounting and speed sensor type are compatible, as well as the motor itself.

I'm really impressed with the Fulgur Mula bike as a whole, the EXT supension in particular. The bike perfectly suits what I want from my bike (small battery for lighter weight, good weight distribution, good handling) but if you want a lardy bike with a massive battery then this isn't the bike for you. It's like comparing a Porsche with a diesel AUDI.

 

[Spiff]

The grease goes on the drive gear. The main shaft is on sealed cartridge beaings, not bushings.

The statement that crankshaft has bushings and not bearings comes from a Youtube video of a spanish LBS:


But it is not an "Official" statement so he may be wrong

 

[cappuccino34]

The statement that crankshaft has bushings and not bearings comes from a Youtube video of a spanish LBS:


But it is not an "Official" statement so he may be wrong

The main gear to the crank MAY be bushes, as others are too, but the main side bearings are 100% definitely cartridge bearings, you can see them in the pictures and the videos.

 

[cappuccino34]

Bushes would have too much drag and wouldn't last long at all either, sliding surfaces rather than rolling.

 

[three dots]

Yes, I already saw some reviews of bikes and moto, but I am also interested in the opinions about the motor design approach and long term results, and although @Bearing Man might not have seen a real one, he might have an opinion about the design and expected reliability.

I'm also hoping to find out more about the Polini motor and how to service it. I've got one on a three-year-old Bianchi e-allroad, which has lots of torque and power, more than needed, really, but there's a metallic creak from somewhere around the cranks, which I suspect might have to with wear in the bushings mentioned above.
What complicates the situation, also, is that a local bike shop who now sells a Basso with a Polini motor, and has investigating getting the motor serviced, has so far reported that it would need to be removed and shipped to Italy, taking roughly 4-6 weeks.
Does anyone know how much of the motor assembly is user accessible? I'm going to install a new chain on the off-chance this helps?
I also haven't been able to find a reasonable UK source for the Polini grease that's supposed to go into the little port on the motor.
The battery life seems pretty good -- with 11,000+ km, it can manage a 60-mile round trip on one charge, if I'm sparing with the assist and save it for hills.

 

[cappuccino34]

A creak is more likely either the crank arms need tightening or the motor mounting bolts need tightening.

I bought a couple of tubes of service grease from the shop where I bought my bike, Berkshire Cycles. It took a while to arrive though but I don't actually need it yet because it's only done just over 1000 miles.

To fully service the motor you're supposed to be an approved service agent and there's a service support plate to support the motor whilst you service it.

I'm tempted to get myself 'qualified' to do my own service and buy the plate, plus any other kit required, and do it myself. Sending stuff to the EU for service or repair has become an arse since Boris messed up the Brexit deal, probably full of mulled wine on Christmas Eve.