Do I need a spacer between rear hub and freewheel? (+ pics)

[ihategeeks]

Warning, several questions ahead.
I have a 9C motor and a 7speed DNP from ebikes.ca.

Do I need to put a spacer between the freewheel threads and the freewheel . against the motor?
This is not something provided with the kit.
Motor |(spacer?) |Motor Threads for FreeWheel | Freewheel

So I would have after screwing everything together.
Motor|Spacer|FreeWheel
Is this unnecessary? Is there any real threat of over-torquing the freewheel to the motor casing?
I have a ring that I can use for this, the problem is that the freewheel gets pressed up on the other-side against the dropout because it is sticking out farther than the lip of the axle. Even without the spacer it just barely does that.

motor|spacer|freewheel|dropout

The provided washers are not compatible with the freewheel, they just sit against it too instead of slipping inside of it.
I've spent a lot of time trying to find a washer that will go inside of the freewheel to the axle lip so the freewheel isn't jammed into my dropout.
I tried to fabricate something out of vinyl washers by boring it out to the right size with a drill. When I torqued the outer screws the force pressed the vinyl washer right over the axle lip deep into the freewheel area. Fortunately I was able to pry it off with pliers. So, that was a bad idea that resulted in panic


Is what i need one of these?

Alternatively. Is there a freewheel that is shorter than the 7speedDNP that I could swap in? Eliminating the need for the pictured spacer?

 

[lbz5mc12]

So basically you don't want to spread your dropouts to get the washer in, correct? You may have to to keep the gears from rubbing on the frame. As far as the freewheel, you shouldn't need a spacer between it and the hub, all that would do is put the gears even closer to the frame. A freewheel on a hub motor is the same as a freewheel on a standard hub, it's not going to torque onto the threads anymore then it normally would on a regular bike hub. If you're worried about it getting stuck, you could just grease the threads before you screw on the freewheel. The freewheel tightens on in the direction you pedal so the grease won't make it thread loose but it should make removal easier later on. The washers aren't supposed to slip inside of the freewheel. That part of the freewheel is in a fixed position and the gears spin over it. There should actually be a nut that extends past the edge of the freewheel and the washer is supposed to rest up against that. If there's no nut on the threads that extends out past the edge of the freewheel you may need to find a long cylindrical spacer to put on the axle and slip into the edge of the freewheel so that it extends out past the freewheel and then the washer should rest up against the spacer. A lot of the cheaper Chinese hub kits come with spacers that perform the previously mentioned function. I'm not sure where you can find that kind of spacer though. A local hardware store might have something that will work.

 

[ihategeeks]

I haven't tried really tightening the freewheel to the hub in fear of overdoing it. Maybe I won't need a cylinder spacer. If I do I need to figure out what size I am looking for because every spacer I've tried so far has been too big resting against the freewheel or too small to get around the axle

 

[Drunkskunk]

you might need a spacer, you might not. fitting a spacer is part of aligning the freewheel, and it's need is determined by several factors. If the chain hits the motor, and/or the derailer hits the motor when you have it set correctly to move the chain to the largest gear, you need a spacer. Otherwise, you probably don't.

If the freewheel is hitting the dropout, you have other problems. That side is spaced with a sleve that fits over the axle.

 

[ihategeeks]

If the freewheel is hitting the dropout, you have other problems. That side is spaced with a sleve that fits over the axle.

That lip in the axle is not reaching the dropout.

You can see it barely not making it here

And here the washer lays right against the freewheel, which will grind into whatever.

Do I need a spacer that goes to this lip in the axle? Is that the 14mm one that ebikes.ca sells.

 

[lbz5mc12]

Yeah you can't put a washer right against the freewheel or it won't spin. You might try looking for a nut that'll thread on and it should fit under the threads. As long as the nut is completely flat sided with no lip it should fit right in. You may need a couple nuts. It almost looks like they didn't install the axle correctly because there sure is a lot of unthreaded axle sticking out on the left.

 

[wesnewell]

You have to have something to keep the dropouts away from the freewheel. Most kits come with an ~2 inch spacer and at least one washer like you pictured. The spacer should stick out at least 1mm past the end of the installed freewheel. Add washers as require to get chain and freewheel clearance from the dropout. If your dropouts are wide enough you could use a single jam nut like pictured below, but the best solution would be a long spacer tube. Could be made from 9/16-5/8"ID conduit or anything similar.

 

[Kingfish]

I have a washer on both sides. It adds about 1.5 to 2 mm more space - just barely enough for clearance. The slotted washer fits nicely inside the freewheel and provides a broader shoulder for spreading the load against my aluminum rear-suspension frame. It is an inexpensive investment that resolves fundamental issues with 7+ speed freewheels. I found that my dropouts can handle 1-2 mm additional spread without issues, but more than that - and it becomes a PITA to mount.

Also - they make a larger diameter thin version, and I use that style on the FWD - particularly to enhance clearance for the disc brake.

Just do it. KF

 

[Drunkskunk]

From the pics I see you have 2 problems. First, thats a 11 tooth freewheel, that has a smaller than normal opening at the end. And second, it's a 7 speed. the 9C motor was designed for a 6 speed. You can use a 7 speed only if you can fit the washer in the end to space it, and unfortunately, with that 11 tooth high gear the normal ways of spacing it out aren't going to work.

*The easiest answer is use a 6 speed as it was designed for. 7 speeds will work with a 9 continent motor on most bikes but not all.
*The next harder up answer is to change to a conventional 7 speed freewheel with a 14 tooth small gear. those have a wider opening and should fit your washers.. take your washers up to your local bike shop and make sure they fit in the end.
*Moving up in difficulty from that is to make a custom spacer. if you have access to a lathe, you could turn down those washers until they fit. Or you might be able to get a machine shop to make a spacer that will fit, but that won't be cheap.

 

[ihategeeks]

I found a drop nut that works. So I went with that. Bike is now fully assembled and just needs a solid tune.
I had no idea the 9c was meant for a 6speed and not a 7speed.
I could have saved myself considerable grief going with that I guess. :?

 

[dogman dan]

Needing the inner spacer or not varies. It somewhat depends on the machining of the motor cover, sometimes you need one sometimes not, to keep the last cog of the freewheel from rubbing on the case.

The other washer on the axle itself is obviously needed. If you can't fit the spacer washer into the hole, you will have to grind one down until it does. If you have an ordinary washer, you need the special spacer washers. You need that flat side to grab on the axle shoulder.

You might be able to hack a spacer, from some steel pipe if you have some the right size.

 

[timmy66]

Similar question --

on a 9c rear hub, the washer that sits on the shoulder (see photo, taken from ebikes.ca ad for 9c) --

the washer normally that would be compressed by the inside of the drive-side dropouts is not very secure here. It's not notched, so it's a real 14mm ID (for axle), which leaves very little surface area touching the shoulder.

Should these kits have had a large spacer covering the axle, the part that's covered up after the freewheel is installed?

Am getting slipping in the dropouts, even under high-torque (low gear) pedal force, because there isn't much on the inside to be compressed, once the nuts are being tightened down.

Thanks, this must be a common issue, but I think particularly the horizontal dropouts of my specific bike (toward forward) make it even worse since forward chain torque is wanting to pull the wheel forward.

Is there a good source for these notched washers? Ebay / amazon / google, very very little.

Workarounds??

 

[amberwolf]

Is there a good source for these notched washers? Ebay / amazon / google, very very little.

SpaceWash2 and 3 on this page are probably what you're after.

http://www.ebikes.ca/shop/electric-bicycle-parts/motor-hardware/washers-and-spacers.html

 

[timmy66]

Thanks @AW/

That's probably exactly the best solution. Just $15 shipping tho to USA.

Gotta be a cheaper source of these things? Surely price per piece from China folks that include them with other kits is a dime or two.

Ebay almost has nothing in this category.

 

[amberwolf]

Note that not all steel is the same, and if the steel is really soft the shoulders just eat into it which loosens the axle nut hardware. You're more likley to get the good stuff from good places like Grin than some random ebay or alibaba or chinese store. There will always be good stuff at those places, too, but not at all of them, and until you get them and they fail you won't know if they were good or not.

I've had plenty of crappy parts; not so many good ones. Torque washers that have tabs I can bend by hand-spinning the axle with a wrench, or even with just pliers; these aren't likely to survive actual motor torque for long. Similarly, have had flat washers that look like the ones linked above, but too soft to be used as shoulder washers--failing as described above.

If there's other stuff you need for your build, you can see if Grin has that, too, and at least amortize that shipping cost across all the items, then it doesnt' hurt quite so much.

I can recommend the Cycle Analyst as a wattmeter, even if you don't use all it's control features. I can also recommend the Cycle Satiator as a charger, especially if you have more than one bike / battery type/voltage to charge up.

 

[MadRhino]

Use 10mm washers that are clearing the inside of the freewheel end. File the washers hole each side to shape a match for the motor axle. PITA, but faster than any shipping.

The other solution is using a shorter freewheel, 6 cogs or less. You won't need many gears with a hub motor anyway.

 

[timmy66]

Thanks for responses;

the other question I'm not so sure about either is if there should have been a larger sleeve that goes over the axle here;

as it seems that any washer here (circled) is sitting on a very small shoulder to provide the resistance back against the inside of the dropout, that's getting clamped heavily by the external securing bolt? Ideally you'd be wanting a full 14mm or so.

Note - mine is installed with a 6 speed freewheel, so this spacer/washer is more providing a uniform surface against the dropouts, instead of just a small shoulder.