Internal hub gears - rear wheel slipping

[songsforpolarbears]

Hi all,

Just returned from my 2nd frustrating and abandoned ride of the weekend.

I have bought a new bike - Electra Amsterdam 3 speed. This is the first time I have experienced internal hub gears. The hub reads: Nexus Inter 3.

I've had the rear wheel off (practicing for if I get a puncture).

However, now, when I accelerate and/or put pressure on the pedals, the back wheel slips. I can 'feel' it slip through the pedals. Then, when I look down the front of the rear wheel is skewed to 11 o'clock and the back of the rear wheel is at 5 o'clock.

So, I remove the shifter (?) thingy attached to the rear wheel, undo the coaster brake arm, undo the wheel nuts. Re-tighten them.

And the same problem occurs again as soon as I accelerate with force.

What am I doing wrong? Not tightening something enough? Over-tightening? Or is there now something wrong like the coaster brake arm being bent? I would estimate I have rode 3 miles with the wheel not true.

Many thanks!

[billynibbles]

There was no harm done in having a practice removal for the inevitable puncture, but it's not uncommon for hub gears to require some re-adjustment after the wheel is put back on as it's often impossible to guarantee that it went back in exactly the same position. You've already spotted that you had the wheel in a bit 'sideways' and rectified that. It should now only remain to adjust the cable control for the Nexus 3.

This video might help.

http://www.youtube.com/watch?v=Nx0I-4JdQ2k

Basically, you put the shifter into middle (2nd) gear, undo the locknut clamp where the cable disappears into the casing over the right-hand wheel nut. This then allows you to rotate the adjuster screw.(It's not unlike taking up the slack in a brake cable). The casing has a window on top with a pair of parallel lines under the lens. You should adjust the cable length by screwing or unscrewing the adjuster until a yellow marker ends up midway between these two lines. Once it's there, tighten the lock-nut on the cable entry and you should find you can get all 3 gears now without that unpleasant 'whoops, it's in neutral' feeling.

You'll may also find yourself having to do this when you move the wheel backwards to take up chain wear.

[thirdcrank]

I'm not sure your problem is connected with the gear cable fitting / adjustment but I'd still preserve / commit to memory / bookmark billynibbles reply for when it is. I think you have reassembled it with the nuts and washers in the wrong order. Have a look at this:

http://techdocs.shimano.com/media/techd ... 655189.pdf

[MacBludgeon]

that sounds more like the axle is slipping in the dropouts, or that's what I take the rear wheel slipping to 11/5 o'clock to mean. If that's the case then you need to tighten the nuts up more, making sure everything is in the right order and orientation.

I have two hub gear bikes and carry an adjustable wrench in the saddlepack on each, only about a 6" one. But I find trying to get the nuts tight using a bike tool/multi tool can be a bit hit and miss.

[billynibbles]

that sounds more like the axle is slipping in the dropouts, or that's what I take the rear wheel slipping to 11/5 o'clock to mean. If that's the case then you need to tighten the nuts up more, making sure everything is in the right order and orientation.

I took that to mean that the wheel was in slightly 'sideways', i.e. not centred up between the two forks when viewed nearest to the bottom bracket.

I think "thirdcrank" may have a point re: the order in which washers and spacers are fitted. It would certainly be worth checking the order, as I'm guessing it would only take 'one washer too many - or too few' immediately under the r/h wheel nut to put the whole shebang out of adjustment.

I suppose the acid test is whether this alone puts the yellow marker back into its correct position in the window (with the bike in second gear). If not, it's possible the OP may have to do a bit of everything suggested.

[thirdcrank]

...However, now, when I accelerate and/or put pressure on the pedals, the back wheel slips. ... the front of the rear wheel is skewed to 11 o'clock and the back of the rear wheel is at 5 o'clock .... What am I doing wrong? Not tightening something enough? ....

As MacBludgeon says, that sounds like back wheel nuts insufficiently tightened to hold the wheel in place and would apply no matter what the gearing system was. I was so busy reading billynibbles excellent stuff on adjusting the cable - one of my hobbyhorses - and finding the appropriate Shimano techdoc to illustrate the tabbed washers that the trees were obscuring my wider view.

[CJ]

Sounds very much like the tabbed washers are out of place. These prevent the axle rotating under the reaction torque from the internal gears. When you feel slip in high gear, that'll probably be the axle turning forwards along with the wheel, thereby loosening the right-side axle nut, which will allow the chain to pull that end of the axle forwards, so the wheel ends up skewed as described.

When you buy a new type of bike with which you are unfamiliar, it's a good idea to ask the dealer to show you how to get the wheels out, and put them back again. So perhaps a trip back to the shop for some hands-on advice?

[songsforpolarbears]

Thanks very much for all the replies.

I have all the washes and things in the right place. I made a big effort to tighten everything as tight as I could.

There was an allmighty CRUNCH about 30 seconds into my ride. No idea what it was. I thought maybe the grooves on the nonturn washer in the left axle slipping into the groves 'made' into the frame?

Anyway, the bike is now working well. The gears are working good. The yellow marker is in the correct position (thanks).

But! The wheel the not straight. Only slightly wonky. At the front of the rear wheel I can fit my finger between the tyre and the mudguard enough to touch the centre of the tyre (when putting my finger in on the right-hand side). I can't push my finger between the tyre and the mudguard on the left-hand side - no room.

Looking at http://techdocs.shimano.com/media/techd ... 655189.pdf

the brake arm clip should not be as tight as the axle nuts. It is a bit awkward to tighten (it is not a clip screw as shown in the .pdf, it is a nut), maybe i am not tighten this enough? Maybe too much? How on earth am i meant to judge the tightening torque?

Many thanks for your help, all.

[thirdcrank]

The reaction arm has nothing to do with how tight the wheel is, which is governed by how tight the nuts are on the axle, subject to everything being fitted in the right order. I think you need to be working on the wheel nuts with the reaction arm's nut and bolt slack. That will allow the wheel to move backwards and forwards within its slot. Positioning and tightening a wheel held with nuts is not particularly easy, IMO as the act of tightening the nuts can dislodge it. I don't know if there is an 'official' way of overcoming that. My method is to get the wheel just where I want it, ie pointing the right way and with the chain properly tensioned, then carefully tightening the nuts - a bit at a time on each side in turn until the wheel is in no danger of being disturbed, then tightening up the nuts properly. (Remember, don't do this with anything longer than you will have available on the road.) Then, and only then, tighten the nut and bolt in the reaction arm. AFAIK, these need only be tightened sufficiently to ensure the nut is properly fastened and will not come undone. The function of that fastening is to prevent the arm rotating with the wheel when the brake is applied. So long as the bolt is in place, no matter how loose it is, the arm cannot turn.

In other words, the only effect the reaction arm may be having here - unless I've completely missed something - is that if you tighten it before you tighten the wheel nuts, you have little hope of getting the wheel in properly.

[niggle]

I think at this point a good close-up photo of both the axle nuts would be very useful. I am a little worried about the noises being reported and wonky wheel alignment and think there is a possibility that the non-turn washers are not installed correctly with the claws engaged in the dropout slot. Otherwise I think a trip to your local bike shop might be prudent. Looking at the photos of the bike model on CRC it appears to have rear facing 'track' style dropouts, which at least means the wheel will not be pulled out by pedalling force I suppose. Does this look like your bike:

[songsforpolarbears]

I really appreciate the replies and you all trying to help with my problem.

Here is some photos:

Right hand side rear dropout:

Right hand side rear dropout with the gear thingy removed:

Right hand side rear dropout with nut, washer and and long, thin spring thingy removed:

Left hand side rear dropout:

Left hand side rear dropout with nut and non turn yellow washer removed:

When the wheel is wonky, the chain sags and rattles against the chain guard a lot.


Here is a video. At 50 seconds, you will notice the angle of the brake arm changes slightly and this allows me to get the rear wheel straight. I just didn't have the brake arm nut loose enough.
http://www.youtube.com/watch?v=XyJEDFDfsSw
Following this I tightened everything up (axle nuts first and then brake arm). I went for a VERY leisurely ride. Everything was fine.
Later the same day I rode across town. I have to ride up a very steep hill. At the start of this hill, I was pushing hard and I was sure I felt the rear wheel slipping! I was right - the wheel is wonky again.

If I can provide any more photos or anything, please let me know. Again, many thanks for all your helps.

[7_lives_left]

Those shimano no-turn washers the same as the ones as I use with my alfine hub, all be it that mine are for vertical drop outs and yours are for horizontal dropouts and are colour coded differently. Do you have left and right mixed up? I can't honestly see them slipping around in the dropouts. The photos are a bit fuzzy but you seem to have the tabs aligned in the slots in the dropout correctly. Does the photo show metal filings? Where are they coming from?

The axle has flats on either side that match the holes in the no turn washers. Are those surfaces undamaged? Both the axle and the insides of the washers.

What does the inside surfaces of the dropouts look like? Especially the inside surface on the right hand dropout. These are the ones that the over lock nuts (?) press against.

If you think the surfaces of the dropouts might have been damaged, you could try adding or removing a pair of links from the chain. That will allow you to move the wheel forward or backward in the dropout so that you are bolting the axle onto a fresh undamaged surface of the dropout. This might cause difficulties fitting the chain case but you could leave that off temporarily while you are sorting out the wheel. You might even be able to see whats going on better as well.

[songsforpolarbears]

I am a little worried about the noises being reported and wonky wheel alignment and think there is a possibility that the non-turn washers are not installed correctly with the claws engaged in the dropout slot. Otherwise I think a trip to your local bike shop might be prudent. Looking at the photos of the bike model on CRC it appears to have rear facing 'track' style dropouts, which at least means the wheel will not be pulled out by pedalling force I suppose. Does this look like your bike:

I know I've said above that I think the washers, etc are installed correctly, but now I'm not so sure.

Yes, my bike looks like that, with track style dropouts (anyone know why the frame builder would choose this? is it unusual to find track style dropouts on such a bicycle?)

A better photo of one rear dropout:

Those shimano no-turn washers the same as the ones as I use with my alfine hub, all be it that mine are for vertical drop outs and yours are for horizontal dropouts and are colour coded differently. Do you have left and right mixed up?

Maybe.

Does the photo show metal filings? Where are they coming from?

Erm, if I understand you correctly, from the frame where the nuts and washers have been screwed against the frame in the dropouts.

What does the inside surfaces of the dropouts look like? Especially the inside surface on the right hand dropout. These are the ones that the over lock nuts (?) press against.

Again, if I understand correctly, the INSIDE surface of the dropouts look like:

If you think the surfaces of the dropouts might have been damaged, you could try adding or removing a pair of links from the chain. That will allow you to move the wheel forward or backward in the dropout so that you are bolting the axle onto a fresh undamaged surface of the dropout. This might cause difficulties fitting the chain case but you could leave that off temporarily while you are sorting out the wheel. You might even be able to see whats going on better as well.

Thanks. Ok, this is what I have done. I took a pair of links off. The chain now fits when the axle is positioned against the frame (in the most forward position possible):

What I need now is to make sure the washers and nuts are in the right order.

NEXUS 3-SPEED HUB w/Coaster Brake SG-3C41 Inter-3 Hub - http://www.shimano.com/media/techdocs/c ... 704663.pdf
This has just confused me more, because I have an extra washer. Or maybe not, flange nut (12), looks a lot different to what I have.

And a photo showing the reverse sides:

I know my push rod is not totally straight. Which could cause a problem but I think it is ok. It sticks out 14mm when slid into the axle, which I have read somewhere is correct.


---------------

When I change gear, the bell crank unit pops off. The bell crank unit fixing bolt's thread no longer works, I think. I can neither screw it in or out. It just turns round and round and round and round and....

[hubgearfreak]

Do you have left and right mixed up?

that's my guess too. i've not had nor do i have any shimano hubs, but it occurs to me that the more positively serrated washer should be on the driveside.

[jb]

You have got the sprocket side internal nut out by 45 degrees by the look of the photo this is stopping it slotting into the slot thus making it have little contact area even when tight and causing it to slip

I suggest you take the wheel right out and start again.