Attaching cogset to custom rear hub (ATV Wheel)

[johndjmix]

Hi guys, we are working on a ebike that uses ATV wheels and tires. We have created several small electric vehicles, some for urban city use, and others for disabled. We have a full machine shop (Lathe, Mill, CNC plasma table, CNC router, etc...).

Im wondering...before we ....(pardon the pun) re-invent the wheel, if there is a simple way to attach a cogset to a custom rear wheel/hub. We have no problem creating a wheel hub in our lathe, but how to attach a cogset to it is the question. The cogset does not have to freewheel, since we will be using a freewheel on the crank....

Any ideas are appreciated.

--John

 

[amberwolf]

If you can use the splined cogs common today, you can simply put that spline pattern on your custom hub.

Alternately you can drill out the splines in the cogs, and make your own keyway or spline set, to match whatever you want on the hub.

 

[d8veh]

I put the threaded part on a motor. The same technique can bu used to fix one to a custom wheel.

You get a cheapo pressed together steel hub, which are very common on cheap bikes. You can either cut off the drive-side or drive the axle tube off with a big hammer. This leaves you with a threaded flange, which you can weld or bolt to any wheel or motor. It will then accept any standard free-wheel with gear-set,

 

[amberwolf]

That's another option, especially if you need the freewheel--it is what I did to turn my front 9C into a rear:
http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=37837

 

[Chalo]

Standard English pattern freewheel threads are 1.370"-24 RH with a 60 degree thread form, about 3/8" (9.5mm) long to the shoulder.

There is the issue of the remover spline for the freewheel, though-- the most common Shimano pattern spline can only admit up to a 19mm (3/4") round axle before it prevents the insertion of a remover tool. That could be a problem if the ATV's axle must pass through the freewheel.

Chalo

 

[johndjmix]

Good ideas guys. Not using a atv axle, just some 3/4 or 5/8 bearing shaft.....

Chalo: you think cutting those threads onto a aluminum hub will hold? Such a short amount of threads (3/8 you said) on aluminum might be weak....

Never cut threads on the lathe before...oh well, I'll figure it out....seems straight forward process..

Hummmm. I'm surprised there is no pre-made hub that has the threads on available for connecting a cassette for a custom job...

--john

 

[Chalo]

Chalo: you think cutting those threads onto a aluminum hub will hold? Such a short amount of threads (3/8 you said) on aluminum might be weak....

Most bicycle hubs are made from aluminum. The worst case for a bicycle hub thread is a loaded tandem bike with a 38 tooth sprocket on the freewheel, being driven by a 24 tooth or smaller sprocket on the crank (350 to 400 lbs-ft at the hub). Freewheel threads work in those situations, though I imagine the freewheel becomes difficult to remove.

Three full turns of a thread are usually enough to carry all the tension that thread size is capable of withstanding. In this case, that would be 1/8" of threads. (Dissimilar materials, like a steel freewheel on an aluminum hub, often benefit from greater thread length. But 3/8" is enough, and if you go much deeper the freewheel will bottom out before it sets up on the shoulder.)

Never cut threads on the lathe before...oh well, I'll figure it out....seems straight forward process..

If you have access to a CNC mill, you could use milled threads. They are generally of better quality than single point cut threads.

Hummmm. I'm surprised there is no pre-made hub that has the threads on available for connecting a cassette for a custom job...

I don't know why anyone would want to do that, without knowing what sort of thing the freewheel or cassette would be connecting to. For most folks, lacing a rim to a hub of your choice sounds like a custom job.

A cassette is not the same thing as a freewheel. You could make a cassette interface on your hub, but that's more complicated than threading it for a freewheel.

Here's an article that describes the difference between the two.

Here's picture of a hub with the cassette freehub body removed:

If you can machine that lobed spline on the end of the hub shell, and tap the nonstandard fine pitch thread for the mounting bolt, then you can use a cassette instead of a threaded freewheel. Making a freewheel thread is easier.

Chalo

 

[ddk]

Good ideas guys. Not using a atv axle, just some 3/4 or 5/8 bearing shaft.....

Chalo: you think cutting those threads onto a aluminum hub will hold? Such a short amount of threads (3/8 you said) on aluminum might be weak....

Never cut threads on the lathe before...oh well, I'll figure it out....seems straight forward process..

Hummmm. I'm surprised there is no pre-made hub that has the threads on available for connecting a cassette for a custom job...

--john

-also-
sickbikeparts.com and staton-inc.com both stock 5/8" axle adapters threaded for freewheels.
-wut I use since I lack a machine shop or the patience of amberwolf

 

[johndjmix]

chaio, If its that simple....ill just thread it on the lathe. My CNC mill consists of a router mounted to my 4 foot x 4 foot plasma table. Its a pain to setup material on it, but surprisingly its acurate to within .01....not bad for such a big CNC table!

My lathe/mill is NOT CNC (yet!). Normally I thread using one of those adapters that holes a die on the tailstock. But since this is a custom thread, im thinking ill have to bite the bullett and learn how to thread on it. This is where I wish my lathe had a gearbox....i have to manuallt change gears to change the speed of the crosslide, pain in the a**!

But that seems simple enough...cut a hub and machine the threads into it. Not a big deal. Any advice on what cutter i should order to cut those threads?

--John

 

[Chalo]

Any advice on what cutter i should order to cut those threads?

There is a specific thread form for 60 degrees 24tpi, but for that job I would grind my own. 60 degree point, a very small flat (or radius, if you're really good) on the tip, and a mild positive rake for moving the aluminum chip out of there.

Aluminum likes to be cut with a high surface speed, but there is no high speed way to cut such a short thread up to a shoulder under manual control. Go slow, give yourself a small relief up at the shoulder and stop & retract when you get in there.

Chalo

 

[johndjmix]

3/8 is such a small thread, i think ill proboly turn the chuck by hand to avoid bottoming out!

Thanks for the advice!

--John

 

[johndjmix]

I came up with an interesting idea. Machine an adapter to bolt to the ATV wheels, then get 2 bicycle rear hubs, put one on each side and bolt through the spoke holes to the ATV wheel adapter I will make.. The combined width should get me close to exactly what I need. If its short, ill make the middle center adapter for the ATV wheel a little wider.

This should solve all problems, and be the simplest way to do it. Although I did order the tooling to thread on my lathe, but im sure that will come in handy one day.

--John

 

[Chalo]

You're driving the right side of both rear wheels?

 

[johndjmix]

Both rear wheels? Its a bike, there is only one rear wheel.

Still torn if i should go making my own threaded hub, or make 2 hubs mate to an adapter.

--John

 

[Chalo]

Okay, I faced a similar issue (back when I had some awe-inspiring equipment to tackle the problem, but not enough free time). I was going to machine my own hub to mount a four-bolt ATV wheel on a bike. I never did get around to that, and I wound up diverting the "bike" wheels to a trike. It all worked out.

Here are some of the issues I see arising if you want to use two rear hubs as the left and right ends of a fat tire/wheel assembly:

The attachment between hub and adapter will have to be strong and stiff enough to withstand bending stress from both vehicle weight and chain tension. Consider using all 16 or 18 holes on each side. Also, the center of a hub shell is not designed to be overhung (only compressed like a column), and thus may not be strong enough to withstand such loading. So you should definitely attach the same-side flange to your assembly unless you can determine that the hub shell you are working with is plenty thick and has a large diameter in the center. A chunky-looking cheap hub may be just the ticket.

This is the sort of shell that might work if you bolt up to the far side flange:

But this hub would not work if you overhang it from the far side flange:

You'll probably need an extra long axle. Common rear axle sizes are 3/8"-26 for solid axles and M10x1.0 for hollow quick-release axles and track axles. The best alternative I have found is M10x1.0 high strength all-thread from McMaster-Carr. You can get 3/8"-24 studs that are leaf spring center bolts for trucks, but then you'll have to use 3/8"-24 hub cones and locknuts from a coaster brake hub. It's not straghtforward.

Chainline (the alignment between chainrings in front and sprockets in back) will likely be an issue, unless you use a jackshaft hub like the Hanebrink Extreme Terrain bikes.

Later examples of these bikes went without the jackshaft, but I'm not sure whether that was by means of an extra-wide crank, a crank offset to the right side, or just a very long chain run that tolerated the misalignment. Surly uses a special wide-set crank called MWOD for their Moonlander bike with 5" wide tires

http://surlybikes.com/uploads/downloads/MWOD_explained.pdf

Your project sounds fun. Good luck with it.

Chalo

 

[johndjmix]

Hey Chalo. Thanks for the pointers. I keep going back and forth on the decision to machine an adapter and not use bike hubs at all, vs use them. I think the hanebrink (A very cool bike, but very different from my design) uses a VERY wide bottom bracket shell / bracket to avoid use of a jackshaft. This is what I will do. Although my bike will have pedals, it is mainly for legal compliance. It will be ridden electric 90% of the time, with the pedals used only when you make a mistake and run out of juice!

As we all know, pedals = access. Being able to ride almost anywhere, roads, trails, etc...is the draw to this bike. The ATV tires (Im actually using 2 ATV front tires, Maxxis Razer XM's), should float over anything, and look VERY cool when cruising around the city. Ill start a thread when I start the build (Within a week).

Once parts start ariving ill start maching the Tripple Trees out of aluminum on the CNC, then the wheel adapters.

Just ordered the freewheel and parts from sickbikeparts, man what a good company. Jim was really helpful and really seemed concerned and wanted to help. I highly recommend them to anyone.

--John

 

[Chalo]

Hey Chalo. Thanks for the pointers. I keep going back and forth on the decision to machine an adapter and not use bike hubs at all, vs use them. I think the hanebrink (A very cool bike, but very different from my design) uses a VERY wide bottom bracket shell / bracket to avoid use of a jackshaft. This is what I will do.
...
Just ordered the freewheel and parts from sickbikeparts, man what a good company. Jim was really helpful and really seemed concerned and wanted to help. I highly recommend them to anyone.

So you're using one of the really long BBs from Sickbikeparts? You should plan to use a rear derailleur or sprung chain tensioner even if you intend to run a single gear. That's because the longer BBs from Sickbikeparts are not exactly straight, and that means they won't maintain constant chain tension on a normal slot-adjusted one speed driveline. If you were planning on having rear shifting, the variation in distance between centers will not be a problem, but out-of-plane wobble in the front chainring could cause difficulty with front shifting depending on the particulars.

That Maxxis tire is quite knobby, and that means quite slow for low-power applications. I used Skat Trak Smooth Buff front ATV tires (knobbies that have had their knobs shaved and sanded off entirely) to minimize weight and rolling resistance. They are still slower than bicycle tires, but acceptable for my tastes-- my ATV-wheeled trike is pedal only. Hanebrink Extreme Terrain bikes mostly used turf-type knobbies that had been sanded down to shallow tread depth, for the same reasons.

I think it's a good idea to make the pedal drive as effective and as efficient as you can, because if it's good you may decide to use it routinely, but if it's lousy you definitely will not. Play it however you like it, but it is more virtuous to use muscle power, and everybody knows it. That's why pedal cyclists resent e-cyclists and some e-cyclists get prickly and defensive about it-- the former think e-cyclists are cheating and/or gaming the access rules, and the latter know it's true, even if they prefer not to admit it. The solution to the dilemma is not to choose one propulsion method over the other; just use both. Your body will benefit, real cyclists and hikers will respect you more, and you'll respect yourself more.

Chalo

 

[johndjmix]

Chalo, I agree, workout is important. Im into running, just ran a 10K last month. Who knows, maybe ill get into the pedaling.

So you have allready done this? (You said you used the skat trac smooth buff tires). How did you accomplish the rear freewheel?

I am using a multi-sprocket freehweel, and derailleur.....so chain tension should not be a problem. What will be a problem is the bottom bracket, even with the width of the one from sickbikeparts it may not be enough, so i might wind up machining my own...

BTW: for you folks that find this threadon a later date looking for a way to attach the freewheel:

http://www.atomiczombie.com/FDAX34%20Trike%20Axle%20FreeWheel%20Adapter.aspx

http://www.ffrtrikes.com/Standard-Aluminum-Freewheel-Adapter-p/freewheeladapter.htm

http://www.staton-inc.com/store/products/7_8_ID_Adaptor_for_freewheel_sprockets_1_10_wide_2_set_screws-983-27.html

The first could easily be bolted to a wheel, and you just wouldnt use the keyway since the axis is not live.

--John

 

[Chalo]

So you have allready done this? (You said you used the skat trac smooth buff tires). How did you accomplish the rear freewheel?

I bought my pair of wheels for a bike, but I ended up changing plans and making a trike with them. I did machine the hubs myself, but they were made to slide onto a solid axle. The bike version would have been made more or less the same way, but with a threaded boss sticking farther out of the hub:

What will be a problem is the bottom bracket, even with the width of the one from seickbikreparts ita may nout be enough, so i might wind up machining my own...

A square taper BB spindle has to be made from VERY hard and strong material; I do not recommend making your own. When I have made my own BB spindles, I started with a Primo Powerbite crank, which uses a larger 22mm spindle with non-tapered square ends. In my opinion, it is the easiest spindle to reverse engineer. You could probably talk one of the small shops that makes titanium replacement spindles for it into making you an extra long version, if you don't want to machine your own.

The best bottom bracket for the Primo Powerbite crank is the American pattern, with big bearings in a big shell. The nice thing about that is that 2" Schedule 40 pipe is just about exactly the right size for the job. You can make the shell just as wide as you please (skin down the outside if you want to reduce weight), and there's no need to thread it-- it's a press fit standard.

Chalo

 

[johndjmix]

Chalo, want to come to NY and help -). lol.

How big did you go with the axle, 3/4"? Im worried about the massive span of the axle, probably 10" or so....thats a lot of stress over a big span. We use 3/4 on our small trike units, but each wheel only hangs out about 4" from the axle housing.

I dont even have the rear freewheel here yet (shipping), but im wondering how im going to get a bearing between that and the frame...or do the rear freewheel setups have a bearing built in past the threaded part? This will be a lot easier once some parts get here.

Yea, ill check out that crank....looks like it might be the ticket, a plus on the 2" pipe!

I started a thread for the build, its going to be a slow build but must be done by Dec 1st, so im on a part ordering frenzy.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=44200

--John

 

[Chalo]

How big did you go with the axle, 3/4"? Im worried about the massive span of the axle, probably 10" or so

22mm is very close to 7/8" (22.2mm). I used 304L stainless steel for my first special BB spindle, 12L14 steel for the second, and 7075-T6 aluminum for the third. For a spindle with a lot of overhang, I'd use 1144 "stressproof" steel, or 4140 CrMo steel like the factory does. But you don't have to have much overhang if you're making your own BB shell; just make the shell wider by the same amount that you're making the spindle longer (which simplifies the chainstays too). You'll also need that much more spacing in the spindle sleeve between the bearings.

Chalo

 

[johndjmix]

Finally got a bottom bracket in the mail (The one from sickbikeparts). Interesting. I dont see why you the center "pipe" section is even needed. If the end cups keep the bearings from sliding outward, and the "axle" has raised sections to keep the bearings from sliding in, why is there even a center cover pipe type thing?

Anyways, If i can figure a way to keep it straight why not just cut the BB axle in the middle and add in an extension. But id never be able to keep it straight when welding. So oh well. Guess ill just make one on the lathe/mill.

--John

 

[amberwolf]

You might wanna pop into AussieJester's first cruiiser thread, where he did exactly that--extend a BB.

 

[johndjmix]

URL?

--john