On the previously mentioned touring holiday, there was another equipment failure that I didn't expect. The bearing in the lower pulley of my rear derailleur disintegrated! The BBB Rollerboys sealed bearing pulleys had done around 10,000 km in a Shimano Tiagra long cage derailleur. Most unexpected and perhaps a lesson to be learned! 25km of hills to go before the camp site...

Stopped of course, and walked to a suitable off road  bit of shade. I was offered a lift, but pride and perhaps misplaced independence motivated me to find a working solution on the road.

Disconnected the BOB trailer and stood the bike on its head. Bit of protective stuff under my seat of course. Could now see and feel that the lower pulley was stuck solid, but not why. Split and removed the chain - SRAM chain with a SRAM Superlink makes it  painless. Another link of this type is the Wippermann Connex, don't know of any others. You can see the Wippermann chain connector link at

http://www.connexchain.com/

As far as I know, the SRAM links and Connex links can be purchased separately, and all SRAM chains are supplied with a Superlink/Powerlink. I've also been known to use a SRAM joining link in a Shimano chain with no sign of trouble and no cycling god struck me down - yet.

Got my tool kit out and undid the bolts/retaining pins that hold the pulleys in the cage and the outer cage plate. A tumble of bits fell into my hand instead of the complete lower pulley. Inspection revealed:

• The 11 tooth annulus of the pulley with the outer ring of the bearing.
• The inner of the bearing.
• A couple of mangled bits of metal that had once been the ball bearing cages.
• A couple of mostly intact bearing seals.
• Some loose ball bearings.
• Ground up metal bits !!

This agglomeration of bits would never be a working pulley again in any shape or form. This in turn meant that I would have no working derailleur, and without the chain tensioning supplied by the rear derailleur, no front derailleur either. In short no gears at all.

There are probably a couple of lessons here.

• Sealed ain't sealed particularly in the harsh life of a jockey pulley.
• Maybe there was a recommended lifetime - I don't know.
• A traditional bushed pulley can be stuffed and still function, once a sealed bearing pulley is stuffed it's just stuffed.

So how to proceed? 

Well  thankfully I carry a chain breaker/cutter in my tool kit and I decided to select a compromise gear ratio and shorten the chain to make a single speed to get me to the camp site. I had plenty of time so no need to panic or rush. My fellow cyclists knew where I was and that I was able to sort myself out, however slowly !!

Being a winch gear climber, and having 25 kilometers of hilly terrain to go, I decided to go for one of my lower gears using the middle chain ring. I split the chain at the SRAM superlink, then wrapped it around the selected chain ring and cassette cog to see where the length would fall. By resetting the rear wheel in the dropouts about a millimeter forward I would be able to have a properly tensioned chain.

I used the chain cutter to break the chain and then rejoined it using the Superlink. Used a bit of care to reclamp the wheel in the slightly forward position. Without a joining link you would need to use your chain tool to join the chain by pressing a pin back into place. My 42/20 ratio on a 20 inch wheel gave around 15 kph at 80 rpm, and allowed me to climb most of the remaining hills.

As I was walking up one of the minority that I couldn't climb, it occurred to me that the chain length I had for the 42/20 would also work reasonably on my granny and biggest rear cog - 28/32. It's all in the tooth count. 42 plus 20 gives 62. 28 plus 32 gives 60. So the chain would be 2 links too long on the lower ratio. Still a little care and maybe it would all work. So undo rear wheel, move chain to other chain ring and cog, reclamp rear wheel. The chain was quite loose, but with care would stay in place. Care meant taking off very gently and spinning smoothly. Climbed two steeper hills that way. Took a couple of attempts to restart on a hill without the loose chain coming off, but pride and persistence won through :-)  So while the last few flat km were painfully slow, they were under my own steam and there is a certain satisfaction in being self supporting.

If you've never used a chain breaker, I advise you to keep and practise on one of your old chains. It's not difficult, but anything unfamiliar needs to be practised before you're in trouble, so you can do the repair with a little confidence.

There's a pretty comprehensive and well illustrated how-to article on using a chain breaker at the Park Tools web site at

http://www.parktool.com/repair/readhowto.asp?id=25

and read your preferred self help bike book for advice on using a chain breaker.

I use a BBB Nautilus chain breaker which has an adjustable anvil to suit any width chain and a shelf for loosening tight links. The handle of this tool includes 8mm and 10mm "spanner" cutouts which are useful as they are the only size nuts on my bike. It's also useful for me because I carry the same toolkit on several different bikes with different chain widths, and because it fits in my tool kit.

There are a wide variety of tools for this purpose and a whole stack of multi tools which include a chain breaker. Tragically I just looked up the BBB web site to see if the Nautilis is still available, and while it is, the handle no longer includes the spanners - pity. You can see BBB tools and the Nautilis chain breaker at

http://www.bbbparts.com

Here's a pretty minimalist tool of unknown quality

http://www.filzer.com/products.php?id=75

Here's a better lightweight tool of untested quality from Topeak which I like the look of

http://www.topeak.com/products/Tools/SuperChainTool

My next chain breaker for the lightweight do anything toolkit is going to be the separate item that comes with the Topeak Alien XS. It's the smallest I've seen and uses an 8mm spanner to hold it, and an Allen key to drive it, both of which I already carry...

Repairs like this are like many things related to cycle maintenance and repair, not necessarily that difficult, but require understanding and sensitivity, like any good relationship.

Chain breaker versus chain cutter... don't really know. My first memories are that this tool was always referred to as a chain cutter, rightly or wrongly. So I suspect chain breaker is the modern interloper. Chain cutter has a ring of the traditional pommy bike shop about it, chain breaker perhaps a US feel and perhaps it also stops their citizens taking to chains with bolt cutters :-) Anyone out there offer enlightenment?