Freewheel threads?

[henrypig]

Hi there - I would like to add a freewheel to this omniwheel (below) that will be mounted at the rear of my wheelchair (a la SmartDrive - http://max-mobility.com/products/smartdrive/). I have salvaged the threaded male part of a standard rear bike hub and mounted it to the omniwheel using the provided bolt holes (which happened to be only 1mm different from the spoke hole chord diameter). The thread size on this hub is the usual 1 3/8" x 24tpi. I will use #25 chain from a motor to a sprocket bolted to the freewheel. But the only #25 freewheels I can find seem to be M34 x 1.0mm female thread. Can I use them on this hub? If not, where can I find a hub/freewheel combination that would work? Thanks in advance.

 

[fechter]

Try here: http://electricscooterparts.com/sprockets.html
http://www.thesuperkids.com/scooterparts.html
#25 chain is pretty common on low-end chinese scooters.

 

[henrypig]

Thanks - but those freewheels are M34 x 1.00mm. I need 1.375" x 24tpi.

 

[spinningmagnets]

I doubt you can find an off-the-shelf bolt-on solution, though I wish you luck. However, You can take a "large-enough" #25 sprocket, and drill out the center with a hole-saw or a jigsaw (the steel will be fairly soft. Harder than aluminum, but not too bad) then drill 4 or 5 holes that place the bolt shanks in the valleys of the corresponding teeth in the FW. Here's one example:

 

[henrypig]

Interesting idea. I'm also now thinking of using a motor that has a bike sprocket, like this one (http://www.monsterscooterparts.com/...moto-9-tooth-8mm-05t-chain-sprocket-1018.html). Any downsides? Gearing would be about right (walking pace) with a 16t freewheel.

 

[fechter]

That sounds like a workable solution. Those motors have a decent track record and are cheap enough.

 

[Chalo]

But the only #25 freewheels I can find seem to be M34 x 1.0mm female thread.

I don't think so. The usual metric freewheel thread is M30x1.0. I can't address other products, but the 90t #25 sprocket from thesuperkids fits right on a bicycle hub without issues.

 

[John Bozi]

Chalo, or anyone could give me some advice...

im running a 4065 hub with M35 (don't really understand m35...)

Im going to run bafang 750w mid drive through it too.

currently I have a dnp epoch 7 speed cassette which I believe is your standard
from sheldon
The standard ISO threading for freewheels is 1.375 x 24 TPI, the same as for standard ISO bottom brackets

I am concerned about not being able to get this off when the need arises.... so wondering on freewheel sprockets probably single speed granny gear style. The thought is that if I can get it off at least I can just take the cog to work on the hub or to replace worn teeth easily.

with my limited vocabulary and understanding of sizes etc. I resort to google image looking for what Im trying to say... something like this?

Ill be running a raceface front chainring and standard bicycle chain...

is there an easy solution to mount threaded to splined products such this as single cog? 44t oneup

basically my goal is to climb steep mountains slowly with the mid drive and then use the rear hub motor on flat.

thanks in advance

 

[etard]

Ahh, the infamous threaded to splined problem! There has been a few attempts at this this by our buddy Thud, but it was found to be extremely laborious and costly so only a few examples were ever made. You might try sending him a message in the hopes that there is one or two sitting on the shelf. Basicly, he created a grinder that cut splines into a freewheel.

 

[Miles]

Also: http://endless-sphere.com/forums/viewtopic.php?f=28&t=13532

 

[Chalo]

It's not that hard to remove a single-speed freewheel with a robust 4-prong tool interface, or one with a bottom bracket type spline interface. You have to remember to apply liberal amounts of grease, or ideally anti-seize compound, to the threads before assembling. It helps to use a vise to hold the remover tool, and to retain the tool loosely on the axle with an axle nut and washer as appropriate.

For adapting a large sprocket to a cassette spline, it may be best to modify and repurpose one of the aluminum carriers used by fancy cassettes. A busy bike shop might be able to salvage one from a worn-out cassette.

If you are willing and able to use normal bike chain for your motor drive, there are ready-made solutions such as 40t and 42t aftermarket cassette sprockets you can purchase and mount on your freehub body without modification.

 

[John Bozi]

Chalo,

I am using a normal bicycle chain, however I am using a crystalyte hub motor which only takes thread on hubs. (and a mid drive)

so the problem is that they do not match where they meet on the freewheel, there are no thread on freehubs that I know of.

 

[Chalo]

In your earlier posting, you said you had a 7 speed cassette, not a freewheel. Many folks use the terms interchangeably, but the problem you are addressing means that the technical approaches will be different.

Am I correct that you intend to drive a hub motor with an external motor? What advantage could that possibly have over using a larger hub motor, or just a more powerful battery and controller?

 

[John Bozi]

Yes my mistake on the cassette...

Reasoning is simple, I already run a large vented hub in a 20" tyre at 5kw. It has reached it's threshold... It still overheats up steep mountain sections where it is in the wrong speed.

The mid drive is to be able to keep the bike running as slowly as possible primarily to give the hub a break to cool down and possibly to use for 0-20kmh parts of all rides all the time.

so really I would like the biggest possible granny at back....

sure there are problems everywhere you turn, but they started the moment we put wheels between us and the ground.

 

[Thud]

To the op:
I am 99.999% certain the freewheel threads in every example linked to is in fact a 1.375x24 thread freewheele size...not sure where the 34mm #s in the descriptions come from but they are correctly identified in the same description paragraph.
I have most of those examples on the shelf....

@john bozi:

I would like the biggest possible granny at back

look into an "overlay" or "cheater" sprocket set up if you are serious about granny gearing.

 

[Warren]

You can find NOS, Suntour 14-38, 5 speed freewheels on eBay. But they are not cheap.

 

[Chalo]

You can find NOS, Suntour 14-38, 5 speed freewheels on eBay. But they are not cheap.

Also, they use the notoriously fragile 2-prong Suntour remover interface, and often can't be removed without destroying the freewheel body (though the sprockets can be removed first and transferred to another compatible freewheel body).

For what it's worth, I have found that the Suntour 14-38t 5-speed freewheel will usually index shift perfectly with a Shimano pattern 6-speed shifter and corresponding long cage derailleur.

 

[Warren]

Before the the crash, and their ultimate closer, I worked at an old bike shop that had a pegboard wall full of NOS freewheel bodies, and sprockets from back in the day when you could build up a freewheel with sprockets of your choosing. :-(

 

[John Bozi]

I had a look at those multi coloured and brown freewheels and they look old and nasty.

I think I am going to have to just start with my current freewheel and do a few rides and see if the granny is enough for the steep mountains.... Need to see which gear matches the real world bike geometry up hill and traction ability too.

If it isn't will go the custom route to a single speed 44t and hope to hell I can get the freewheel off and find a way to keep chain tension on my full suspension...

thanks for all the advice...

 

[John Bozi]

Just to share what info I have dug up on this topic.

splines finally!!!!!! (I won't be buying one but one day who knows....)

Also from my email to sickbikeparts.com

Yes our freewheel should mount to your hub and not a problem using any of our chainrings. You can mount the chainring on either side of the freewheel to adjust your chain line as necessary. You may also add spacers as required to get the chainring where you want it.

Hope that helps. If you have any other questions let me know.
Thanks,
Jim

Hi Jim,

context to my questions:
I'm going to run a dual motor system on my bike. One is a hub motor which takes a thread on freewheel and the other is the bafang bbs02 mid drive. The hub does 90% of the ride, peak 5kw and the mid drive I want for slow granny gear work solely.

Can I use your front heavy duty freewheel on my back thread on hub? http://www.sickbikeparts.com/catalog/product_info.php?products_id=62

Can I use it to adapt your 44t chain rings such as http://www.sickbikeparts.com/catalog/product_info.php?cPath=21&products_id=38
or maybe less teeth (I haven't fully decided).

Is there a way to dish outwards to get a better chain line?

Now I have to work out the right teeth combination. 30t front but back? I am guessing that 44t in a 20" wheel might actually be too slow at 100-120 rpm of the mid drive.

I was aiming at climbing stuff which tends to be just before the limit of traction failure, which also is hub bog down and overheat.

Problem with going single speed is I practically give up the use of pedalling along at 20kmh.... losing a free 100w ......... ahhhh :?

 

[boisrondevens]

http://endless-sphere.com/forums/viewtopic.php?f=28&t=64342

This is a 52t chairing