RC reduction Simplified

[kevo]

Adrian wrote: Unfortunately the 6374-200kv never went on sale,

Oops, my error. Edited out now.

Thud and Adrian, how well does the 8085 perform compared to the 6474?
Is the ACS Crossfire any quieter than the White freewheels?

[adrian_sm]

Okay I am new to this whole free wheel crank thing. So bare with me.

So the cranks are mounted to the BB as usual, but you have a freewheel screwed onto on crank. Then you have to mount two chainrings off of that. One for the motor chain, one for the drive chain to rear wheel.
And you need a wider BB or some offset or something to give you enough room for the freewheel?

So the shopping list would be:
1) ~$20 - wide bottom bracket
2) $25 - freewheel cranks
3) $20 - ACS crossfire freewheel
4) 2x $22 44t chainrings

Still requires a bit of customisation to get two chain rings mount on the freewheel. Slot the freewheel teeth, and sandwich it between chainrings with some appropriate spacers. Nothing too tricky.

Does that sound about right?

Oh, and your reduction unit of course to drive it all.

[EDIT] @Miles. Thanks for the link will read through that now.

[Thud]

You have it right Adrian.
The hardware package form SBP has the spacers & such for bolting the chain rings to the freewheel & to each other...the bits & pcs are not the top of the line bolts,washers. I upgrade the fasteners & use the spacers.

Actualy you can put the FW cranks onto a standard bottom bracket. but the wider options allow for some seriouse clearance for battery boxes & huge motors. if you know what i mean
(edit to add)the wide BB are actually offset far more on the left, for clearance of the china girl 2-stroke engine kits.

As far as compairing the 63mm to an 80mm motor.....apples & oranges. The 80mm motor starts out with a 27% size advantage directly in the leverage ratio that makes outrunners so atractive.

when it comes to delivering tourqe, size allways wins. There is no replacment for displacmet.

[Green Machine]

I want one of these units for sure. thanks thud for building this.

I have been looking for simple solutions not involving hub motors.

Subscribed.

[deVries]

Now you have me thinking about a BB drive through the gears on my FS bike with this reduction unit. Damn you.

Isn't Thud just about the most tempting or the most lusty open-source porn on ES?

I'm addicted to reading about everything he does... remember the good'ol daze "back in the day" of crotch fireworks & controller fries! & the eventual triumphs!

the wide BB are actually offset far more on the left, for clearance of the china girl 2-stroke engine kits.

Why not drive the front crank on the left side then? Too complicated or too expensive to do or ?

As far as compairing the 63mm to an 80mm motor.....apples & oranges. The 80mm motor starts out with a 27% size advantage directly in the leverage ratio that makes outrunners so atractive.

Apples & oranges recommendations for the following typical scenarios please! ...

Would the 80 drive a moped frame/build to 35mph with typical car-speed acceleration to maintain that speed for 5-10 minutes for stop-n-go in city traffic/driving?

Would the 6374 be a "perfect fit" for a 35mph flats-max. 25mph nominal for 50-lb. bicycle with excellent but typical car acceleration (non-racing) city riding in traffic vs the possible "overkill" of the 80 for same setup?

[Thud]

hmnnn. If pressed for a recomdation,
I have to say the biggest motor you can afford will be the better value.
A bigger motor will handle any stress better & the larger bearings, shafts & everything will have the advantage of mass working for it.
A smaller motor will be operating much closer to its "critical" point.
For those reasons alone I would allways recomend the bigger motor.
& is not about speed or wheelies. running a motor at less than its full potential will just extend its life...& if the situation arises, you have the power on tap to conqure that hill.

But a 6374 will pull you along at 30+ fairly easy also. It will just be a little closer to the red line in doing so.

I have found the tiny 5065's will push my big butt to 30mph. but it requires flat gorund (or better yet a down hill ) fully inflated tires & a 2-speed unit to get it rolling.
I just bought 5 more for experimentaion (new cooling system design for racing) & I have a couple 16" kids bikes that will be fun to try this reduction unit with. (neices & nephews will have a blast...grand kids are still too small yet)
http://www.leaderhobby.com/product.asp?ID=9394001224329
the price is right to play with....the key to happyness is low expectaions

but seriously, bigger is better.

[deVries]

Any thoughts, comments, opinions, or recommendations about this... ...

the wide BB are actually offset far more on the left, for clearance of the china girl 2-stroke engine kits.

Why not drive the front crank on the left side then? Too complicated or too expensive to do or ? Advantages vs disadvantages?

[Miles]

Any thoughts, comments, opinions, or recommendations about this... ...

the wide BB are actually offset far more on the left, for clearance of the china girl 2-stroke engine kits.

Why not drive the front crank on the left side then? Too complicated or too expensive to do or ? Advantages vs disadvantages?

As I understood it, Thud was just stating a fact. If the offset isn't needed for the freewheeling mech, it doesn't matter that it's on the left-hand side. In any case, it's easy enough to rebuild them with the offset on the right-hand side.

Yes, you can drive the left-hand side, but it's not a simple matter if you want to retain the freewheeling cranks: viewtopic.php?f=28&t=35846&p=520537&hilit=bottom+bracket#p520537

[MitchJi]

Hi,

So freewheeling cranks. Where? How much?

One option for freewheeling cranks is Matt's (higher quality and more expensive than the sickbike parts). Not sure about price and availability but he did say he'd sell individual components of his system:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=34753

I am pushing to make the highest quality crank drive that uses the stock derailer and pedal system that I can while keeping an eye on the cost. It looks like the kit consisting of motor, drive unit, FW cranks with chainrings, all mounts, motor and all hardware will come in at around $1,500.

#4 The freewheeling crank. This is one thing I am really excited about! It will use a second support bearing to eliminate the overloaded freewheel bearing issue that is so common with freewheeling cranks. It will also use standard 130mm BCD chainrings for multiple ratio options. I am very excited to have come up with a solution to the FW crank bearing issue. I am not the first to do this, but I think it is the first to be readily available. My system will come with this new FW crank system and a new lengthened bottom bracket.#4 The freewheeling crank. This is one thing I am really excited about! It will use a second support bearing to eliminate the overloaded freewheel bearing issue that is so common with freewheeling cranks. It will also use standard 130mm BCD chainrings for multiple ratio options. I am very excited to have come up with a solution to the FW crank bearing issue. I am not the first to do this, but I think it is the first to be readily available. My system will come with this new FW crank system and a new lengthened bottom bracket.

His motor would probably be a good fit for Thud's drive:

#1 Motor. This system will be compatible with Astro motors, but for those who are looking for lower power, lower cost, and lighter weight while retaining quality, it will also be compatible with a small outrunner based on a standard Maxx Products outrunner. This motor will retail for under $200. The normal motor is $180. However, my motor will use a longer shaft and a few other minor changes. Also, this motor is readily available and I can pick them up 15 minutes from my house! And if someone manages to smoke the motor, the stator/windings retail for $50 and are easy to replace! This motor uses high-end bearings and is, overall, a very high quality motor! I am thrilled to find this option so close to my house. Also, these motors have been tested in very dirty environments. So, I am confident it will run well in this application. It is also a very quiet motor.

[Thud]

Why not drive the front crank on the left side then? Too complicated or too expensive to do or ? Advantages vs disadvantages?

Disadvantages to left side driveing a crank:

Lefty loosy: The right side already allows for acceptable freewheel solutions. the left side would reqiure southpaw threading & freewheels that barely exist....& none that exist currenty in a quality we can accept.

Stay too the right: Since drive lines are already on the right side...why not capitilize on the established engineering & component compatibilities?
There is a good argument for this. Since your clogging the right side with drive lines, it frees the left side for batteries & other items....driving both sides of the crank will consume valuable space between the pedal circles.

Advantages: None present in my current thought pattern.....other than it would be "different" & unique which allways adds 5 Kool points

Add that I have enough ideas for crap to build, to fill the rest of my life 20x over.....bike cranks are refined enough for me dissmiss them as perfected & focus on other things

[chroot]

Your bike is perfect to use the grinder drive setup viewtopic.php?f=28&t=26699

Beautiful work.
I am considering BB mid-drive of 750-1500w, & as light & simple as possible, for a recent acquisition.

Introducing.....JPG

Light, simple, RC, BB driven NuVinci N171.
This sure would fit the bill. Especially with the C.A. RC development.
Cannot wait to see a couple examples in action.

Your pricing is very reasonable.
I have started another penny jar.
Best of luck expanding your empire.

[deVries]

Beta unit is boxed & in the mail.

this is going into the beta stage now...we'll see what meets the testers expectations & where we can improve the packadge.

Has your beta tester started a build thread, or have you gotten any feedback?

Any ETA or idea when we should know something...

[Thud]

I been holding back a bit waiting for some input from the test mule (& working ferverantly on the Bully getting it ready for the the Md race& the usual distractions)

kinda thought we'dve seen something by now.....but he is a student & active in sports...prolly tied up in school stuff.

I made a new match plate to speed up the molding proccess & have some more shafting on order to make up the 1st production batch.
I also have a batch of 80-85's I intend to re-wind & offer up a few complete kits. but every thing takes time....

[GITech]

I thought I was subscribed to this Thud..but I haven't gotten any emails for post updates...

I've been away, I broke my collar bone into 3 pieces... I've got some catching up to do!

I've updated my thread with some pics. Sorry and thanks again Thud Bud!

Jay

[kevo]

Sounds like good progress, quite exciting actually - thanks Thud!

[spinningmagnets]

Why not drive the front crank on the left side then

A freewheeling crank-drive works best if the motor-chain and the pedal-chain to the rear wheel are on the same side. Although its possible to have them on opposite sides, engaging the motor would cause the pedals to turn. If the chains are on the same side, you can hold the pedals still while powering the bike with the motor.

Whether or not the pedals are forced to always move when the motor is on, this is the big difference between the Stoke-Monkey, and the Urbancommuterstore mid-drives. viewtopic.php?f=6&t=37741

[amberwolf]

Although you could build Miles' version of the BB pass-thru that freewheels the cranks on the actual BB shaft.

[etard]

Is there a review yet? Whoever has this thing in their dirty mitts needs to post some sort of review/ progress report, summertime is upon us...

[Chambers]

viewtopic.php?f=28&t=38053


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