Chain reaction

[Matt2matt2002]

Good advice. I'll get the eccentric out and take a proper look.
I could never get a good look down those pesky holes, even with a torch.

Am I correct in thinking its the points that bight into the eccentric and stop it moving?
The 2 bolts themselves don't tighten any thing?
Think I've asked this before.

Matt

If I need a new eccentric, are we talking big bucks?

[geocycle]

Good advice. I'll get the eccentric out and take a proper look.
I could never get a good look down those pesky holes, even with a torch.

Am I correct in thinking its the points that bight into the eccentric and stop it moving?
The 2 bolts themselves don't tighten any thing?
Think I've asked this before.

Matt

If I need a new eccentric, are we talking big bucks?

That's correct Matt, the screws bite into the thick aluminium. If they are not tight enough they could move.  You'll see this by scoring channels on the EBB.  If you need a new EBB they are £30 http://www.sjscycles.co.uk/eccentric-bottom-bracket-insert-fits-raven-tour-mk1-sport-tour-only-prod11656/ (I recall you have the raven tour) but, I have a brand new unused one I could sell on as my new RST frame is different. I doubt you will need a new one but pm if you want to give it a go.  Nb you will need to remove the bb from the old shell which can be a challenge! Are you using the C spanner to adjust? Final thought is the EBB in the right way round... Text on sjs site says:

'NOTE: circular manufacturing mark by 3rd cutout to go on chainring side.'

[Matt2matt2002]

Thanks.
I have never removed the bottom bracket and since the fault occurred after 2,000 miles I would guess its in the correct way.

I'm not clear on the last line of your post. Where can I read the full text?

Thanks for the offer of yours. I'll remove the bracket and post some pictures Last time I tightened it, I think I felt as if it would slide out ok. Why might it be difficult to remove?

Re the spanner. No. I dont  have one.
I loosened the 2 bolts and the turned the bracket by hand. Held it firm and then tightened the bolts. First time the chain finished up too tight so fiddled about a bit and second or third time, it stayed slightly slack.
By using the spanner would I have avoided the fiddling about?

Matt

[JimK]

Not sure what the problem is exactly. But one thing I would say... do not tighten the bolts and then fiddle about. Once you have tightened the bolts you have committed yourself - you have made a dent in the EBB that is not going anywhere. If you then loosen the bolts and fiddle a little and retighten the bolts, you now have two very closely spaced dents that have most likely merged into a funny sort of oval. You don't want an EBB that has funny ovals. You want nice discrete circular dents.

The EBB should slide very easily through the frame once the bolts are loosened. You might be able to slide it over far enough to get a really good look at the dents. But that is different from removing the "bottom bracket". The actual crank bearings of course are fastened inside the EBB. I have yet to venture into that business myself. I have seen some youtube videos where wrenches go flying. Those threads can be pretty snug. You certainly need the right tool corresponding to the bottom bracket bearing set on your bike.

I use a head lamp when I am messing around with the EBB. Probably that is why I manage to look down those little holes and can see what is down at the bottom. The head light is very close to my eye so I can see down the hole while the light can get down there at the same time. I find this very useful. I unscrew one of the bolts all the way and then fiddle with the position until I like the tension on the chain and also so I can't see any other dent in the EBB down the hole from which I have removed the bolt, or at least any dent down there is barely peeping off to the side. Either that or there is an existing dent right in the middle that I will reuse. I will loosen the chain a bit until I find either open territory or an existing dent that I can reuse. That might make the chain looser than I really want but that's the deal here. Precise tension is not possible. Properly spaced dents in the EBB create discrete steps and you just have to pick from the available steps or create a new step that is plenty far from existing steps.

I generally do end up fiddling about with the chain tension but I don't tighten the bolt until I am done fiddling. Of course this means the stupid EBB can slip while I am fiddling so that means triple the fiddling but c'est la guerre!

[geocycle]

Thanks.
I have never removed the bottom bracket and since the fault occurred after 2,000 miles I would guess its in the correct way.

I'm not clear on the last line of your post. Where can I read the full text?

Thanks for the offer of yours. I'll remove the bracket and post some pictures Last time I tightened it, I think I felt as if it would slide out ok. Why might it be difficult to remove?

Re the spanner. No. I dont  have one.
I loosened the 2 bolts and the turned the bracket by hand. Held it firm and then tightened the bolts. First time the chain finished up too tight so fiddled about a bit and second or third time, it stayed slightly slack.
By using the spanner would I have avoided the fiddling about?

Matt

The last line of the text is from the SJS link to the EBB shell.  I just quoted it verbatim.

The EBB will be easy to move side to side or remove completely if you take a crank off.  It is the bottom bracket inside the EBB shell that I have found more difficult to remove from the EBB shell.  You wouldn't need to remove this unless you decided to change the EBB shell.

It is much easier with a c-spanner.  I have one I don't need so pm me and I'll send it to you.

[Matt2matt2002]

Many thanks to all those who have contributed so far.
I hope the following doesn't try your patience too much.

First pictures shows bike upside down ready for me to attack the EBB
Think you'll agree the chain is on the slack side? It jumped off a couple of days ago.



Next up I tried to remove the crank arm. Bolt out no problem but then it would not slip off. I have a rubber hammer and gently tapped it. Then I bit harder but no go.
Are they tough to remove? Any tricks to this game?





Decided to put everything back together and pay attention to centering the EBB through the frame ( bottom bracket hole? whats the correct name please?)

Next 2 pictures show how it sits now.
Even?





That's it folks.
Chain reasonably tight - well, not so slack I think it will jump off.
Must say it can be very tricky when it happens - especially in traffic.

Comments and thoughts please.

Matt

[rualexander]

You need a crank extractor to remove the cranks, unless they are self extracting bolts which by they aren't by the sound of it.
The indents on the eccentric BB look reasonable but a couple are doubles which may be close enough together to cause slippage in use.

[Matt2matt2002]

Just noticed one of the pictures didn't come out. The one showing the bolt out of the crank arm.

I was expecting the arm to come off having removed the bolt.

Am i right or wrong?

[Danneaux]

Matt,

Please don't use a hammer in an attempt to remove the crank. The crank socket has been wedged onto the square tapers of the bottom bracket spindle, so it won't simply slide off when you remove the bolt. Rual is correct; you need a crank extractor.

This should help going forward: http://www.madegood.org/bikes/repair/remove-a-square-tapered-crank/

I would suggest removing the chain before attempting to remove the crank.

All the best,

Dan.

[Matt2matt2002]

Thanks Dan.
I don't have one of those removers at the moment.

So am I correct in thinking that I won't be able to remove the EBB completely u less I remove the cranks?

I was able to slide out the EBB a little to see the indentations into the soft EBB.
One of the pictures shows an indent off to the side. Not good?

Re relocaring the EBB; just use a good wye to line things up?

The last 2 poctues show slightly different views of my final setting of the EBB. Even?

Thanks
Matt

[geocycle]

You cannot remove the EBB completely without removing the crank.  You need a crank puller described above to remove the crank.  It's really important to screw the crank puller tightly and squarely into the crank before attempted to extract it otherwise you can easily strip the crank threads.  Definitely worth looking at some videos online  first or ask your LBS. To remove the bottom bracket from the eccentric bottom bracket shell you need another tool (or ask your LBS).  But, looking at the dents I think the EBB is fine.  I just line mine up so the vertical surfaces are flat against the edges of the frame as I think you have done.  

Sometimes the EBB can move when you tighten the screws and some tension is lost.  The bespoke spanner will help!

[davefife]

So am I correct in thinking that I won't be able to remove the EBB completely u less I remove the cranks?

I was able to slide out the EBB a little to see the indentations into the soft EBB.
One of the pictures shows an indent off to the side. Not good?

Re relocaring the EBB; just use a good wye to line things up?

The last 2 poctues show slightly different views of my final setting of the EBB. Even?

Matt, where are you in the UK? you need to speak to a bike mechanic who can advise you/keep you right, do you have a LBS?    Dave

[Danneaux]

you need to speak to a bike mechanic who can advise you/keep you right, do you have a LBS?

Agreed. Dave's a good 'un, with many satisfied repeat customers.

Best,

Dan.

[Matt2matt2002]

Aberdeen.
Can I walk to you?

[davefife]

Matt, your welcome at Dave's Bike Shed any time! Its a bit far from furry boots city tho I do back onto the east coast mainline so if you were travelling south get off at Kirkcaldy or Inverkeithing and come along to me KY3 0XE.

I dont know the bike shops out your way but a quick search shows Holburn Cycles as an indie LBS albeit road biased, do you know them?  You also have http://becycle.wordpress.com/  who seem to rent workstands to the public and provide advice.  My reckoning would be these people could be helpful to you.  Why not visit without your bike and have a chat/coffee to sound them out?

Looking at your pictures your eccentric will be ok, at worst with it removed you could dremel off any edges that protrude.  Tandems also use eccentrics for tension of chain between pilot and stoker and I have seen well abused ones, but a good mechanic can always have them retain tension; only in extreme cases would a new eccentric be required.  Indeed I did a brace of bottom  brackets in a tandem today - liking the aliteration!! eccentric was slightly ovalised in the bottom bracket shell but no worries all good again.
cheers
Dave