RC drive with 3 speed gearbox idea, will it work??

K

ktronik

100 W
Joined
Jul 13, 2008
Messages
139
Location
Newcastle, Australia
A bit of backround...I work as a bike mechanic, and have built a heap of these 3 speed Nexus hubs into wheels for our Australian postal service, that haul big arse loads of mail around the place on the heaviest bike you ever seen, then they add a 500w Geared front hub motor and batterys to it, then add the mail...yes heavy...

the hubs never seem to fail, yes given they don't pedal them as hard as they use to, now they have electric...but still I would like to see if we can interface this hub into a RC drive as they are cheap.

A good way to give a greater speed band with better efficiency and less peak amps at low RPM. But really, for me to have a over drive, for when I am pedaling fast and would have little load on the motor... :twisted:

With the hope to control the 3 speed hub electronically as a further step in the future.

SO two ideas for RC drives

RC motor to Nexus hub, back, belt driven, in a side by side config, to the 3 speed hubs sprocket, I would make a 'belt pulley to nexus adapter', probably use a belt and pulley type, that are in use on current systems. better yet an adapter that can take different pulleys for different systems.

so we are using the hub as 'jack shaft' as well to drive a bike chain, via a 'right spoke flange to sprocket adapter', could go a spline or screw fitting so to use a freewheel if needed.

this drives the right side of the bike in a dual drive method, or to the front crank system

w option to drive left side rear wheel with 'disk to chain ring adapter'

OR with different gearing a RC motor to Nexus hub, nexus hub also being a friction roller...

lots of work still to do, but might just work, as a future project, after I get my first RC build off the ground... a simple friction drive for road bikes...

Yes I am a RC newby and want you to tell me why it won't work :D

thx

Ktronik
 
Hi Ktronik,

First I'm a newbie to this RC world, I have talk with many people here at ES about RC set up and how to do it.

Based on their knowledge and experiences a Nexus setup (3 speed hub) will be good for 2000 Watts or less and may be 3000 Watts if you talking care of it. Gary (GGoodrum) as no problem with is Astro 3220 and is 3 speeds SA hub but he told me that he didn't use this ebike as it maximum and very often I think.

For now the best way to use a shifting transmission to power full RC set up is to use "Thud" 2 speed transmission this transmission can be shift under big load and Thud as doing an amazing job and this transmission is good for 8 KW and over about the max power just ask Thud about that.

But any RC set up for an ebike will make noise more than a Hub set up (I'm not a big fan of hub motors anyway).

Then I have the same the dilemma as you have, and I don’t know how to do it or wich way to choose and i'm continuing exploring differents ways, I hope its help good day!
Black Arrow
 
Ktronic,
If your looking to pedal along with your system (superman style i call it) then look at the simple friction drive set ups...way too easy on the fabrication & really fits "hypermilling" to a tee.
I also have an old shimano 3-speed that will turn into a jackshaft one of these days. most of the stuff I build would require a 90t chainwheel to keep up. BUt with sensable gearing I have run tiny 50mm motors with great effect on my 20" bmxer. (its running a 63mm currently & the pedals are for show).

There are some recorded failures of the internal hubs, but they have been pounded on. I think a cush drive (rubber mounted) sprocket would do wonders for longevity & reasonabe rideing to keep the shock loads light. (but really, wheres the fun in that?) :p
 
ktronic, I am glad you want to work on a 3-speed hub as a transmssion. Since RC stuff is still developing, there is still much to be sorted out. My own friction-drive build is going painfully slow while I try to learn on my feet. Just be aware there will be stumbles along the way. Sometimes expensive stumbles!...

I want to see more RC-drives built and data posted about what works (both high-end, and low-end), and so far I don't know of any Nexus-jackshaft RC-builds. I think the idea has a lot of potential. Enough data has been posted about making a de-spoked hub-motor a non-hub drive, that perhaps using a Bafang (or similar small geared hub) to drive a 3-speed jackshaft might be a more reliable plan with a greater chance of a fairly trouble-free success.

Thud has posted that he is pretty happy with #25 chain as the high-RPM half (primary) of his driveline, and I have read about successes using #219 chain and 5mm-HTD rubber toothed-belts/pulleys for the primary. Most seem to use regular bicycle chain as the final drive. You might start a build parts-list for each one of these to see which one gets all the squares checked off first, and the costs/difficulties of each.

You have mentioned you have access to some machining resources, so that is a fantastic start, as some part of your build is likely to need a custom adapter. The Nexus hub has been broken before by some builders, but I have read that it was more due to shock-loading the engaged teeth, rather than a blatant weakness. Several people are working on a programmable soft-start method, and Matt is reporting very good success with a slipper-clutch.

Any one of the configurations you mention seem "possible", so I guess it would mostly depend on what you would enjoy creating. Bubba seemed to know that his builds would evolve rapidly, so he started out using particle board for rapid prototyping, and that seemed to work out well for him. In spite of all my slow and careful planning, I also have several big changes I've decided I have to make to my as-yet unfinished friction-drive....
 
I think you will end wanting a low-kV motor. The 80mm motors (larger, heavier, more expensive) are much more than you need. The lowest kV's they come in (If I recall correctly) is 170-kV, and 130-kV. The smaller motors (50mm diameter are likely to be adeqaute concerning their power and heat-shedding ability (especially with 3 gears!), but the lowest kV I recall was around 250.

The mid-sized motors (63mm diameter) are growing in popularity, and although Hobby king may have a lower-kV available somday soon, there is a 170-kV motor available right now, the 63-74-170, which is also one of their "black" motors, advertised as having better NSK bearings. http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=7870

Do the Nexus hubs you have access to have the disc-brake flange? That may prove useful for attaching one of the pulleys/sprockets you end up choosing.

What type of rear wheel hub do you want to use? will it also be a Nexus 3-speed, or perhaps a common freehub with a conventional cluster of externals gears? You still have many options. No single way is standing out as the 'best' yet, and much still depends on whats easily available to you, and your top-speed goal.

I think there are several Nexus models, can you find out the gear ranges of the models that are available to you? (or just the model numbers, the gear ranges are online). What diameter of rear wheel will you be using?...
 
Best internal gear hub?
http://endless-sphere.com/forums/viewtopic.php?f=28&t=16264

Power transmission through a 3 speed hub?
http://endless-sphere.com/forums/viewtopic.php?f=28&t=9311

Internal gear multispeed hub torque stresses
http://endless-sphere.com/forums/viewtopic.php?f=28&t=15242

3 speed hub as jackshaft. Questions?
http://endless-sphere.com/forums/viewtopic.php?f=28&t=19203

Nexus 3 conversion from coaster brake to disc
http://endless-sphere.com/forums/viewtopic.php?f=28&t=17362

Direct-drive 3220 setup with a 3-Speed Hub...
http://endless-sphere.com/forums/viewtopic.php?f=28&t=12267

Adapter for 2 right-side freewheels on internally-geared hub
http://endless-sphere.com/forums/viewtopic.php?f=28&t=7192&start=15#p195140

Fitting chainrings to hub gears
http://endless-sphere.com/forums/viewtopic.php?f=28&t=11031

http://endless-sphere.com/forums/viewtopic.php?f=28&t=10428&start=45#p186407
lesdit: "...My offroad only bike is using an 8 speed hub, but it is serving as a jack shaft right before the final rear sprocket..."
http://bikemag.com/gear/gt-internal-drive.jpg
 
A real goldmine link from Miles!:

"Catrike Three Speed" ...By: 12p3phPMDC

http://endless-sphere.com/forums/viewtopic.php?f=28&t=9339
file.php
 
OH MAN, thanks SM!! *****************link-o-rama******************


Great work on the 'catlike trike' Link!! what killer combo!! very close to to what I was thinking, but he has solved a few problems, I would have had, easily, by adding another jackshaft and mini reduction, with the belt from motor interfacing the, first jackshaft, to chain to 3 speed hub, he has keep to ready made sprocket adapters. totally nice job!!

The hubs we can get are a nexus coster hub or same with roller brake...working on one today, so snapped this with my phone, pic is of what it looks like with the roller brake off, this would be a better option than having a back pedal brake to worry about...

nexus1.jpg


So my disk adapter (maybe later for a bike of mine) or my sprocket adapter will perhaps, spline on to this and be held in place by clamping the side of the adapter to the side of the hub flange, via the holes you see on inside of spoke holes

if I use it as a rolller it would be a 50mm roller... more soon

or I could start with the centerlock disk version, and do as above, center lock to 6 bolt, then use a 6 bolt sprocket...all I need then is a belt adapter to nexus hub sprocket driver

K
 
HI Guys,

THX this post is very useful and I will not go with the RC route for my next project (personal choice and budget :cry: ) but i like to thank you all for your patience and answer when i was asking you allot of questions in PM :wink:

But one thing for sure I'm really impressed by the works, time and knowledge of the RC people we having here congratulation for those amazing works! :wink:

Good day!
Black Arrow
 
I keep hearing that the Shimano-Nexus line is the one to concentrate on when the 3-sp hub subject keeps coming up. I'm sure if someone already had a Sturmey or other IGH, it could be worked out, but I think now I will concentrate on collecting Nexus links and solutions.

In the past, I have siamesed a sprocket onto an aluminum disc in order to then add a 47T chainring to a rear wheel. Matt makes a beautiful unit that is stong and light (in the non-hub resources stickie), and I'm adding this pic as an example of a disc adapter with a recessed pocket so the chainring will be more inline with the original sprocket (chain-line and drop-out/chain-stay width is a constant restriction on custom builds). the pic is from a push-trailer...notice the rim had custom spoke-holes drilled so they could use the Nexus on a small wheel.

sprocket.jpg
 
 
SM dude rocks it out again!! you have echoed some of my thoughts with the belt driver for the nexus sprocket side...take a big CNC stepper pully, like I have seen linked all over, (has grub screw fittin) and just mod that like, 2 pics up, CNC pully cut to take 22T (or what ever it is) nexus sprocket.

Oh I see that a 'roller to 6 bolt' is done, but had to use a bearing as it is held by the axil... my one would need no bearing...

SO:

RC Motor w small CNC servo pulley to (big CNC servo pulley, cut to fit nexus sprocket) sprocket to nexus hub.

Nexus as 'jack' w 'roller to freewheel adapter'
Freewheel, chain driven to left side rear wheel w big ring mounted to a ISO 6bolt to 130 PCD chaining adapter

this drive will be mounted in the middle triangle of my big dummy...

I can run the motor in any direction right, I am not going to get stumped by say, having the motor, shaft to the right, turning forward, thus forward on LH drive??

K
 
Being held back with the retaining lip and bearing by the axle is actually a fantastic solution and it would work with any freehub without a disc I believe.

Great find!
 
ktronik said:
then they add a 500w Geared front hub motor

thx

Ktronik
Click to expand...

Hate to point out the obvious, but...................

You do know street legal in Australia means no more than 200 watts output, right ????

Amanda
 
commanda said:
ktronik said:
then they add a 500w Geared front hub motor

thx

Ktronik
Click to expand...

Hate to point out the obvious, but...................

You do know street legal in Australia means no more than 200 watts output, right ????

Amanda
Click to expand...

Sorry for my words, and sorry to confuse, I have the same motor as A-post bikes, at home and I was told it was rated @ 500W, so I call it a '500w type'. I am not saying they run 500w into it, as I don't do the electrics on the A-post bike, just the bike stuff, I don't know how much power they are running through them.

Yep good old 200w limit. gota love that

K
 
thanks for the close up pics and vid, I totaly agree, its a great way to go, with the extra support,

If only I could fit a freewheel on the LH side, add a sprocket to 130PCD adaptor, then run the Cesur roller adaptor on the nexus hub with a 6 bolt sprocket, or the center lock version of nexus (w Centerlock to ISO 6bole to 6bolt sprocket)

the key is the LH, freewheel adaptor on the rear wheel, as you would expect better to not have the chain moving when when pedal only...( not so with freewheel on nexus jackshaft hub)

K
 
Ok freewheel on rear hub, left side for motor drive w somthing like htis..

http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=1757&start=45

and 7 spd cluster on the other side...w the USPD LH/RH threaded hub

http://www.evdeals.com/images/CurrieHubSkew.JPG

would use the one with the solid axial

SO: RC Motor w small CNC servo pulley to (big CNC servo pulley, cut to fit nexus sprocket) sprocket to nexus hub.

Nexus as 'jack' w 'roller to 6 bolt sprocket'
sprocket , chain driven to left side rear wheel w sprocket mounted to 22t freewheel using a LH/RH rear hub

K
 
ktronik said:
Ok freewheel on rear hub, left side for motor drive w somthing like htis..

http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=1757&start=45
Click to expand...

Except you'd have to use an ACS southpaw freewheel (reverse threads/locking/freewheeling). Any standard Right-Hand-Thread freewheel would unscrew itself using LHS drive with RH threads (not that the USPD hub has RH threads on the left side of the hub).

Also, adapting a chainring adapter to a 16tooth freewheel requires either bolting through the teeth or welding to it, thereby denying the neat convenience of the ENO 22T freewheels with the radial cut-out weight saving slots with which to bolt through.

attachment.php
 
$180 Sturmey-Archer 3-speed with 3rd gear = 1:1, uses fixed gears so the freewheel must be located somewhere else on the drive. (Thanks, jmygann!). the SA hub "may require" some type of power snubbing and/or ramp-control to prevent breakage at high-power levels.

http://www.benscycle.net/index.php?main_page=product_info&products_id=10167

http://overthebarsinmilwaukee.wordp...ew-sturmey-archer-sx3-three-speed-fixed-gear/

$130, A Left-Side-Drive flanged sprag-clutch FW and also a LH-threaded hub. One of these with a #219 Kart sprocket would be really great! perhaps use a disc adapter to attach Extron spockets to this?, so a future tooth-count change would only be about $22.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=22377&start=0

548_thumb.jpg


http://www.pegasusautoracing.com/productselection1.asp?Product=9806

9806.JPG
 
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