Perils of self teaching from Youtube - gear cable ruined?

[Roadhump]

A couple of months ago I had the chain, cassette and front rings replaced on my bike. Not being a bike mechanic, I had this done at the LBS. Last week I was out riding and whilst going up a steep hill wanted to change into the lowest gear available, but the chain wouldn't go further than the last but one largest cog on the rear cassette. When I returned home, I had a look at the internet to see if I could teach myself how to adjust the gears, and found a few videos which all gave the same advice about indexing using the barrel adjuster.

I followed that advice, which seemed to work okay, but then I found a loose spoke on my rear wheel so took it to the LBS where the spoke was fixed. When I put the wheel back on I found that the gears wouldn't change properly, the chain wouldn't go further than about the 4th lowest gear on the rear cassette (4th biggest cog) so I tried to go through the process of indexing again. This time I found the shifter was very stiff when trying to change down and basically the whole thing became useless. I looked at either end of the cable and whilst the shifter end seems okay, the end by the derailleur seems to be broken. The barrel adjuster seems to have fallen apart and there is now a threaded piece of metal about 1 cm long around the cable which appears to be designed to screw into the barrel adjuster housing. The cable still runs through the barrel adjuster and is attached to the bolt that secures it to the derailleur, but no matter how hard I try I can't screw the threaded piece back into the housing and consequently the adjuster is now useless. The metal doesn't spin around the cable which means that to screw it into the barrel adjuster I would have to rotate the cable several times which presumably would just twist it.

If anyone knows a solution to this I would be grateful for any advice, but I will probably just go and spend more money in the LBS to get it fixed.

 

[Salty seadog]

@Roadhump I'm no expert mechanic but if you add some pictures of the area it would help the guys who can really help you out.

good luck. By the way when I had the issues you had as in not being able to get all the renge of the gears and then having a shifter that won't move any further it was because the cable had come out of a guide on the rear derailleur.
The other time I couldn't full range was because of a bent mech hanger.

 

[smutchin]

The cable adjusting bolt should screw into the body of the derailleur. It comes in three parts: the bolt itself (the 1cm threaded bit), the outer housing (not threaded), and a spring that goes between the two. Latest generation Shimano rear mechs also have a friction-reducing grommet that guides the cable through the derailleur body. This is an extract from the exploded view for a 5800 series rear mech so you can see how it should fit together - the threaded part goes through the spring and housing, then into the derailleur body:

The full EV diagram is here: http://si.shimano.com/pdfs/ev/EV-RD-5800-3712B.pdf

The cable adjusting bolt should only be used for fine tuning the indexing, not making major adjustments. It sounds to me like what you have done is adjusted the indexing too much, so the bolt has come unscrewed from the derailleur body.

Rather than try to put it back together in situ, I would suggest starting from scratch. It's not a difficult job, just requires a little patience, and is well worth learning to do properly.

First, undo the cable clamp bolt and unthread the cable (both inner and outer). Having done so, see if you can reassemble the cable adjusting bolt using the above diagram as a guide. Then thread the cable back through the adjuster bolt, but don't retighten the clamp bolt yet.

I find the Park Tool guide to rear mech adjustment clear and easy to follow: http://www.parktool.com/blog/repair-help/rear-derailleur-adjustment - this will talk you through setting the limit screws, securing the cable using the clamp bolt, then using the cable adjusting bolt to fine tune the indexing.

If you still can't screw the cable adjusting bolt back into the derailleur body after detaching the cable, then something is probably broken and you will need to take it to the LBS.

For getting cable tension right, a fourth hand tool makes life much easier: http://www.chainreactioncycles.com/x-tools-pro-inner-cable-puller/rp-prod122321

 

[Roadhump]

Thanks for your comprehensive reply - appreciate you taking the time to explain it so well.

I have a nasty feeling the spring has "sprung" off and is somewhere on my garage floor. I'll have a look later and see if I can put it back together.

 

[Racing roadkill]

It sounds as though you were trying to sort the indexing of the gears, with a stretched gear cable, and have overshot the limit of the cable tension adjuster on the rear mech. Before I adjust the indexing, I put the bike into its lowest cable tension setting ( smallest ring / smallest sprocket ) then release the pinch bolt on the mech a bit, pull the cable tight ( as mentioned above a fourth hand tool is a useful thing to have) then retighten the pinch bolt. It's then easier to start adjusting the indexing with the barrel adjuster, without reaching the tension limit of the adjuster, and avoiding the risk of the spring unseating itself.

 

[Tim Hall]

Thanks for your comprehensive reply - appreciate you taking the time to explain it so well.

I have a nasty feeling the spring has "sprung" off and is somewhere on my garage floor. I'll have a look later and see if I can put it back together.

The spring will only have sprung off it you have undone the cable from its clamp and pulled it out, as the spring, bolt and outer housing are all threaded along it.

 

[Roadhump]

The spring will only have sprung off it you have undone the cable from its clamp and pulled it out, as the spring, bolt and outer housing are all threaded along it.

Yes, I see that must be the case. However, I have just had another look and there is no spring. I am beginning to think that for a novice like me, the LBS might be a better option.

 

[smutchin]

Can you post a pic? I'm starting to think I haven't understood your problem correctly.

There's no reason why the spring should be missing. That sounds most odd.

 

[raleighnut]

Not all of them have springs.

 

[Roadhump]

The first photo shows the cable, the ferrule and the threaded section, followed by the (inner) cable passing through the barrel adjuster to the capped end. I have disconnected it from the retaining clamp.

The second shows the cable as it enters the barrel adjuster

The third shows the thread about to enter the barrel adjuster, only problem is that is as far as it will go in without screwing into the threaded barrel inside the adjuster, which I can't get it to do. There doesn't appear to be any spring present, unless it is concealed inside the mechanism somehow, but I can't see how that could be, looking at it.

Thanks again for your help.

 

[pclay]

yep, looks like you are missing the spring.....

 

[raleighnut]

Does 'unscrewing' the black bit not help to thread it back onto the adjuster, the 2 parts work together to adjust cable length.

 

[smutchin]

yep, looks like you are missing the spring.....

That's a SRAM Apex mech, which as @raleighnut correctly surmises, doesn't have a spring. Not being familiar with SRAM mechs, I've not seen this design before.

The parts numbered 3 in this diagram show how the cable adjuster bolt fits together - I'm guessing that hex nut has to be threaded onto the cable adjuster bolt before you can insert it through the housing and screw the assembled unit into the derailleur body:

 

[smutchin]

I would also add that the pics show some paint has been scraped off the mech, which suggests it has been bashed about at some point - this may leave you with a bent rear mech hanger, which would also affect shifting performance.

 

[raleighnut]

That's a SRAM Apex mech, which as @raleighnut correctly surmises, doesn't have a spring. Not being familiar with SRAM mechs, I've not seen this design before.

The parts numbered 3 in this diagram show how the cable adjuster bolt fits together - I'm guessing that hex nut has to be threaded onto the cable adjuster bolt before you can insert it through the housing and screw the assembled unit into the derailleur body:
View attachment 337480

I would then surmise that turning the black adjuster counterclockwise pulls the silver part in.