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Cassette wobble
#1
Hi,
I am a newbie to bike repair, i took up the job of restoring an old touring bike just as a run around. I had a problem with the back axle in that the thread was wrecked, i borrowed an axle from an old mountain bike but i am worried my choice is too incompatible.
Anyway, the resulting problem is significant sideways movement in the cassette, independent of the wheel. Is it not tight enough? is the wheel broken where it attaches to the cassette? i don't have the tools to remove the cassette yet, i'm waiting to figure out a diagnosis so that i know whether it is fixable by myself or whether i need to take it into a bike shop? anyway, any info on the cassette being loose and what you think might have happened would be useful, thanks for reading

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#2
Hard to diagnose just from your description, but here's a few things to look at.
- Are you sure it is a cassette and not a freewheel?
- Is the cassette moving independent of the hub (and not just the axle being loose)?
- Are the cassette cogs themselves moving on the freehub (the part with the ratchet) or is the whole assembly moving? You should be able to tell if the right end of the hub where it sits around the axle is moving also (this is actually the freehub)
- Does anything change when you tighten/loosen/remove the axle?
Just swapping an axle shouldn't have affected this, but maybe something is going on.

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#3
Thanks for your help so far, I am going to try and answer those questions
1. You are right, i believe it is a freewheel not a cassette
2. The freewheel seems to be moving independently of the hub
3. The whole assembly is moving.
4. The hub does not seem to be moving
6. My worry with the axle is that it is shorter than the original, and when reassembling, to make it fit to the frame i made the bold move of leaving out a nut and washer on the opposite side to the cogs, so that the piece that fits into the bearings is held there by the frame, i knew this was a bold, and possibly stupid move, but when i put in on and spun the wheel there appeared to be no movement on that side, and the wheel runs reasonably true for such an old wheel. Is this the cause of the movement of the cogs on the other side of the wheel?
7. Is it the case that the freewheel simply needs tightening onto the wheel?
thanks anyway,
forgive my ignorance of correct terms,
I'm doing this with the hope of doing everything possible myself, but also on a budget, so rushing out and buying new wheels and things would be the preferred option, but its not that financially viable
thanks

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#4
The hub bearings and the freewheel are really pretty independent. So it's unlikely changing one affected the other. Cassettes are slightly more interconnected.
The freewheel is tightened every time you ride, so unless you removed it, really no way it "came loose". Older freewheels often develop some side to side play. It may just be this you are seeing. Did it change after you swapped the axle, or is it jsut possible you didn't notice the play until then? A little paly in the freewheel often won't hurt anything. If you have index shifting, it may make the shifting hard to adjust. And it is a sign the freewheel is wearing out. But you still might get plenty of use out of it. I'd try riding the bike some. If it shifts ok and doesn't skip or jump under heavy load, it's probably fine.
On the axle you've got a slight problem. Mountain bike axles are usually a tiny bit longer than road bike axles. It wouldn't surprise me if you needed to take out a spacer so it would fit up into the frame normally. But it sounds like your problem was the axle itself was too short and you didn't have enough thread left to get the nuts on the end?
Taking out washers and other spacers is no big deal. But you really need to have both the piece that fits intot he bearings (cone) and the lock nut that goes outside that. What you've done will "work". But you'll mess up the bearing adjustment anytime you take the wheel off and it will be very difficult to get the bearing adjsutment right in the first place.
If there's enough clearance on the gear side, maybe you can remove a washer from there and put the locknut back on the left. Of jsut flex the frame a couple millimeters needed to get the wheel in there anyway.
I'm fairly confident you didn't get the axle bearing adjustment perfect. You want the nut that goes into the bearings (cone) as loose as possible, but where there is no side to side play in the wheel. Best to hold the tire gently and see if it rocks side to side at all. Having this too loose or too tight will drastically shorten the life of the bearings.
Don't get frustrated though. You're on the right path and learing a lot.

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#5
I'm really impressed by these detailed answers, thanks so much
It is indeed possible that the problem existed before i changed the axle, however, i did ride the bike a couple of times before i started working on it, and i didnt have issues with jumping, so i suspect this issue had been caused by something i have done.
The issue i came across with the axle was that the large spacer on the side of the freewheel is too large, and that i could not fit in all the various parts along the axle so that this system of parts could fit between the two sides of the frame, i tried flexing the frame a little, but there was not enough play to solve the problem. The system i have in there is as you say "working", ans im sure you are right that the bearings aren't perfect but the wheel runs very freely so i seem to have done ok.
I've taken the bike for a ride and i am experiencing jumping, this isnt surprising as the side movement is significant.
There is a very small amount of side to side movement in the wheel, but this does not cause a problem and seems independant of the freewheel movement. If this freewheel is worn out should i replace the free wheel or am i going to have to buy a whole new wheel?
Also, could this jumping be worsened by the fact that i have not yet put time into setting up the gearing? at the moment i have the cable set so that it provides tension to hold in one gear alone. The gearing and new brake pads was next on my list but since i noticed this movement in the freewheel i have felt a little defeated, i had exams, which i have now finished, and the project came to a bit of a standstill. I would now like to put effort and hopefully not much money into finishing it off.
I am trying not to get too frustrated but i havent made any significant progress for a while until talking to you.
anyway, this was my starting point essentially, (not a photo of my bike but the same model and paint job)
http://images.google.co.uk/imgres?imgurl=http://velospace.org/files/t_scorpiofrontside.jpg&imgrefurl=http://velospace.org/viewcluster%3Fc%3D353&usg=__WATTBu8SCw_gxT9WiZxQL_uDnuk=&h=150&w=200&sz=45&hl=en​&start=5&tbnid=y05qX5AXe2hLbM:&tbnh=78&tbnw=104&prev=/images%3Fq%3Draleigh%2Bscorpio%26gbv%3D2%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DG
the paint job was wrecked and so were the stickers, so i got rid of it with solvents and put on a black paintjob with red handlebar tape. The issue is that it looks nice, but i cant ride it yet cos of this silly freewheel, what do i do next?

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#6
If the freewheel is worn out, you can replace just that and not the whole wheel. I can't think of anything you could have done that would have affected the freewheel itself. But something must have changed. Have you done anything to the chain?
Before you just start swapping parts, you should try to figure out what is "jumping". Is it jumping between gears or is the chain jumping up over the top of the teeth? Does it only happen when you put a lot of force on the pedals, or even if you're pedaling lightly. Does it jump every time the pedals go around or every 2-3 pedal rotations? These can all indicate where the problem is. Chain skipping can be hard to diagnose and sometimes you do just have to start trying new parts. But it could be something very simple like a derailleur adjustment or a stiff link in the chain.
On the wheel, the side to side movement is independent of the freewheel. It means that your bearings are a little too loose. When it's like that, the wheel will rotate very freely, but you are putting extra wear on the bearings. You might need to track down some different spacers so you can get the axle set up properly.

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#7
thanks again, I haven't done anything with the chain apart from remove it, i haven't changed the length or put a new one in.In terms of the jumping is takes place every 2-3 pedal rotations i would say, and when pedaling lightly rather than with force. What does this tell you?
the side to side movement in the wheel is very small and there isn't room for any more spacers in between the two parts of the frame, its a tight fit with what is there, so i may just have to cope with that one, its only slight, i hadn't even noticed it until you asked.
The chain seems to catch the back of the next gear up so it tries to change onto that gear, then it fails to do so because the tension in the chain isn't right. derailleur adjustment might solve that but even if i can get rid of this jumping i am not happy with this side to side movement of the freewheel in itself, and i'm sure it wouldn't be good for the chain, if it was slight i would be less worried, but i consider it to be significant.
A new chain might not be a bad idea, but i'll probably go down that road if i have to replace the freewheel. One thing stopping me doing that is that the freewheel seems to be fine in terms of its teeth and the construction seems unbent, and although i'm sure this chain could move more freely it still operates. I really need to go out and buy a lockring tool and a chainwhip and try taking it off the wheel? then maybe replace that and the chain? or is this unnecessarily drastic at this point?
thanks

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#8
I'm betting you have a stiff link in the chain. It takes 2-3 pedal rotations for the chain to go around once so a stiff link will jump as it goes through the tight turns of the derailleur about that often. Pedaling heavily also will smooth it out some because you are putting more tension on the chain. It is very common to have a stiff link when you put it back together because all the little plates and rollers get pressed together.
The proper way to fix a stiff link is using the upper pegs on your chain tool. But the quick trick is to find the stiff link, bend that link so it is in a V shape, and flex the chain a little side to side (90 degrees from the way it is designed to bend). That will usually settle the parts in the right place and free up the link.
You can find the stiff link by pedaling backwards as you watch the chain go through the derailleur. You should be able to see when it jumps a little. Feel the links in the area where it jumps and you should find one that does not rotate as easily as the others.
-------------------------------------
On the spacers, I was suggesting finding some narrower ones than what is on there now so you can make some room for the missing lock nut. But what you're doing now will work, just be aware it's going to wear out the wheel faster than normal.
Last point, note that you need a lockring tool and a chainwhip only for cassettes. Freewheels use a different tool (and there are several different ones depending on the brand of freewheel). Everything we've discussed above applies to both, but don't buy tools until you've confirmed which you have.
good luck

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