750 W Chain Puller; Fits Most Bikes (+Video)

[Warren]

Ron,

"Primary drive is thru half link chain, for the small free wheel, and quietness"

How does the half link chain help anything? It is still 1/2" pitch. And the bent side plates tend to straighten out, making for a weaker chain. The value of half links, is they allow you to hook an "inny" to an "outty."

I work in a bike shop. The half link chains are sold to BMX kids 'cause they look cool. But they stretch them really quickly.

[spinningmagnets]

I don't see any chain tension adjustment. I can visualize adding shims between the where the motor mounts and the main housing. Half-link may allow for less shimming to get an acceptable tension.

I'm sure you are correct about BMX kids stretching half-link chain, but not all half-link chains are created equal in quality and strength. With the half-link chain located in the primary drive position instead of at the final drive to the wheel, I believe it will probably work out well enough. Either way, field testing will soon sort out where changes and upgrades are needed.

[Ypedal]

I"m running half link chain on my 3rd and 4th stages of my RC bike, with an astroflight 3210 and HV110 on 48v.. so far so good.. I had to go with it because regular links would not give me the adjustments i needed...

[Warren]

" I had to go with it because regular links would not give me the adjustments i needed"

Regular chain allows adjustment in 1" increments. A single half link will allow you to adjust in a 1/2" increment. A whole chain of half links adds no benefit. It will always be heavier, and weaker, than a comparable straight chain.

[RWP]

This is one very sweet setup.
Love the clean design. You have a winner.

Roy

[Ron Z]

The primary reason for using half-link chain is to facilitate primary chain tension adjustment, and to eliminate the need for a chain tensioner. Only a 1/4 inch adjustment is necessary. I use KHE chain, which has a cut-away on each link. I believe this eliminates the slapping of the chain sides on the small 13 tooth freewheel. I may be wrong.

There is no need for shims when adjusting primary chain tension. The silver cap screws go thru the inner mounting plate (the one closest to the BB), and are threaded into the outer plate. The black cap screws are threaded into the inner plate and press against the outer plate, they set spacing. The procedure is: Loosen the four silver cap screws. Adjust the four black cap screws for chain tension and plate alignment. Tighten the four silver cap screws. Done.





I have four systems nearly complete (short two small parts). Next systems late June early July (motors). Check the Items for Sale - New topic for introductory pricing (lower). The item should appear next week.

[kfong]

Nice simple way to adust the chain. Great design. The parts look anodized?

[comradegerry]

What a great setup, clean, functional and compact, brilliant. best of luck with your continued product development, it really is looking great.

Gerard

[Miles]

Ron,

Please could you give us the exact weight of the 3205?

Thanks.

[Ron Z]

The weight of the 3205 motor with 6 inches leads that are terminated with CC 5.5mm male bullet connectors is 688 grams or 1.51 lbs.

The total drive system mechanics, including primary chain, but not including crank chain wheel, is 3181 grams or 7.0 lbs.

[Miles]

Thanks Ron.

It looks like the peak efficiency is only a percentage point or two below that of the 3210? Which is good news.

[Hillhater]

The primary reason for using half-link chain is to facilitate primary chain tension adjustment, and to eliminate the need for a chain tensioner. Only a 1/4 inch adjustment is necessary. I use KHE chain, which has a cut-away on each link. I believe this eliminates the slapping of the chain sides on the small 13 tooth freewheel. I may be wrong..

you only need one half link in the chain to make the 1/4inch adjustment, the rest could be regular chain.
side play can be eliminated by selecting the correct chain to match the sprockets.

[spinningmagnets]

The procedure is: Loosen the four silver cap screws. Adjust the four black cap screws for chain tension and plate alignment. Tighten the four silver cap screws. Done.

It took me a couple reads and some staring at the pics to understand this. In this application, I believe the four black screws would be referred to as "jacking bolts". You are making quite a splash by posting one great idea after another!

Whether someone is interested in high-performance or better efficiency (same miles from a smaller battery pack, or, more miles from the same pack) giving the motor 2 or more gears is one of the best options. Keeping the motor in its efficient RPM range during more of your trip, means less heat in both the motor and also the controller (less heat-damage, and also less battery watts used as waste-heat). Motor-gears also means less peak amp-draw from the battery, which translates into good performance from average C-rate packs.

I have recently determined to use a Nexus-3 that is driven by a small motor (for all of the reasons stated above), and I have studied gearing a motor at length.

Matt has shown that for early adopters, a high-quality system with premium components will sell for a price that allows you to survive in a competitive hobby. BB-drives have the potential to provide both great hill-climbing and also higher speeds, where most builds must choose only one or the other.

This is a VERY good development!

[Warren]

Ron,

I would like to suggest a simpler, lighter approach to your BB (bottom bracket) mount. Rather than have the plates run on bearings on the BB spindle, just make the holes in the plates large enough to fit on the bottom bracket shell, before you install the BB. Many aluminum, and most steel frames would have enough BB shell hanging out beyond the down tube, and seat tube to allow the plates to slide on there. Many will have interference problems at the back of the shell, from the chainstays. This can be simply avoided by cutting off the ends of the plates, leaving just 2/3 of the hole. No bearings needed, allows a narrower Q, and will even work with modern hollow spindle, cartridge BB's.

Granted, it won't work with all frames, but where it does, it would be much simpler.

Warren

[Green Machine]

Ron,

Do you think its possible to run a schlumpf planetary speed drive in place of the regular crank set and turn this baby into a two speed?

http://www.cyclemonkey.com/schlumpf-innovations.shtml

[Miles]

Do you think its possible to run a schlumpf planetary speed drive in place of the regular crank set and turn this baby into a two speed?

Practicality aside...Why go to all the trouble of coupling at the cranks for 2 speeds?

Don't let me inhibit the flow, though

[spinningmagnets]

I "think" adding a Schlumpf would work just fine, but at Schlumpf premium prices it may be unneccesary. Since any type of BB-drive provides the motor with the use of the rear-wheel gears (3 speeds for a Nexus-3, and 14 speeds for a Rohloff), adding the Schlumpf would give the motor between 6 and 28 gears.

I think it would work, and when you are not using power, the Schlumpf would continue to provide its main feature of having two BB-speeds with in a compact package to provide rock-crawling clearance. The Schlumpf also provides BB-gears without an external conventional derailler and one stock chainring, so it may prove challenging to add a second chainring, but I think the archives here prove that many unconventional solutions are "possible".

[StudEbiker]

Rather than a Schlumpf, a Dual-Drive or Sturmey-Archer equivalent will provide you with all the gearing you could possibly need for much less $$$.

[Ron Z]

I have been testing the system for about two weeks, and need to say something about performance. The test bike is an Electra Townie with Nexus 8-speed IGH. The gearbox output rpm is 300. The max motor driven cadence is 100 rpm (13/39). and the secondary drive is 46/19). The starting gear is 4th. The battery is a 6 s LiFePO4 rated at 42 amps max. Nominal voltage is 25.

The system easily goes to 30 amps, with brisk acceleration. You definitely get the feeling that most of the power is going to the rear wheel, as throttle response is crisp at the 30 amp level. Top speed is 24 MPH, limited by the gearing. A comfortable cruising speed is 17-18 MPH. even with slight grades and moderate headwinds. The input amps will go to 45 when loaded. At this current level the battery voltage sags and the CC controller low voltage soft cutoff (23 volts) starts rolling back the throttle. It is hard to tell what's soft cutoff and what's loss of efficiency. I think it is safe to say peak power is 1 kw.

The test bike has a totally upright seating position, and wide handlebars. I have physical limitations that limit how hard, and how long I can pedal, let's call it moderate to light pedalling. I run an 8 mile test loop with light grades and light winds. Keeping these facts in mind, the energy usage at 17 MPH is about 18 watt hour per mile. If speeds are kept at 15 MPH the energy usage is 14 watt hour per mile. and at 12 MPH, 11 watt hour per mile.

I ran the bike for a few miles at 30 amps against a 20 MPH headwind (sea level, and 65 F ambient). I immediately drove the bike into the garage, out of the wind. The latent heat of the motor conducted to the surface, where the max temp was about 110 F. With that, I think 750 watt continuous is reasonable, under a variety of conditions.

[Ron Z]

The cranks shown are Vision IPS freewheeling cranks. A freewheeling crank is necessary to prevent the pedals from spinning when under motor power (bruised and broken ankles).

The freewheel in this application is lightly loaded due the fact that the motor pulls one direction and the bike chain pulls equally in nearly the opposite direction. Net force near zero.

I don't like these cranks any better than anyone else for the reasons stated under this topic. The "Sick Bike Parts" and Cyclone alternatives are more of the same. I think the 750 watt power level is near the limit for the IPS cranks. Someone please make and sell a better alternative! The proposed ENO double bearing freewheel sounds promising.

[Green Machine]

Ron,

How loud is your bike when compared to say an optibike? Or other mid drive bike?

Do you get a lot of engine/ chain clatter noise at say 20mph?


A video of your test rides would be optimal...just flag down any random teenager and give him 5 bucks to video you on his smart phone and upload it instantly to youtube.

[pdf]

I think you are on to something here!

[stoney]

I like what I see

[Ron Z]

Now includes video. http://www.youtube.com/watch?v=ytYuosP2Blg

[Jamzz]

It's quieter than I expected.