Wednesday, 1 October 2014

A night in with the spanners

A couple of weeks ago, my much anticipated shiny new drivetrain parts arrived.  Once the younger kids were in bed, and my wife was happily ensconced with the TV and a brew, I set to work on the upgrade.  I’ll apologise in advance for the poor pictures but in my defence:
  1. They were taken on a Blackberry (not usually the mark of quality photography)
  2. I managed to get a greasy smudge on the lens from the outset of the exercise.  This does give the photos a certain “1970’s Top of the Pops Starburst” feeling though, don’t you think?

Shiny new bike parts
I’m very lucky I suppose in that our house came with a built-in bicycle maintenance room.  Unfortunately, until I build an extension to house a separate kitchen, I have to share it with the sink, oven, dishwasher, washing machine and food preparation surfaces.  You can’t have everything.
Would be better without domestic appliances in it!
In a previous post, I mentioned how much my chain had stretched in use and here’s the proof.  Bicycle chains have a pitch of ½ inch so therefore the distance between twenty pins should be ten inches.  You can see from the photo below that the actual distance is more like ten and a quarter.  It may not seem by much but in terms of metal parts which have to mesh together accurately, it’s far too much! 


Without further ado, I set to removing the old chain.  Usually, this is a simple job with a chain-breaker tool and one I’ve done dozens of times before.  However, by inadvertently picking a particularly stiff pin to remove, I managed to break my (less than trusty) chain breaker.  Don’t buy cheap tools kids; it’s just not worth it.  It is also at points like this that you regret starting a job quite so late in the evening, which must be finished by the following morning…

It was all going so well up until this point...
Having no alternative, I consulted the modern cycle-mechanic’s friend – Google.  There I found a brilliant tip which involved using a small punch (I used the one from the snapped chain breaker), a hammer and something to support the back of the chain to drift the pin out manually.  I have to say that, while it was a little fiddly to line everything up to start with, once the pin starts to move, it’s a very useful emergency technique. 

Improvise. Adapt. Overcome.
Following this, I whipped out the back wheel and removed the rear sprocket.  This is a pretty straight forward task which only requires the removal of the single split-ring holding the sprocket in place.  I use a small, flat bladed screwdriver for the job, with caution as I’ve managed to gouge my hand on this job before.  Happily though, the operation was completed this time without medical emergency.  
Inevitably, every job involved a seized bolt or two and I had to work to get out a couple of the chainring bolts.  However, with a bit of gentle encouragement and a splash of WD40, they came undone in the end.  Again, this job would have been simple had I owned the right tool to hold the back of the chainring bolts, but I made do with a steel ruler.  A workable alternative, but somewhat fiddly.
Just out of interest, here are a couple of shots which show the state of my worn sprockets compared to the new ones.

Worn sprockets (front)

Worn sprockets (rear).  Or maybe the contents of a ninja's pocket?
I must now beg forgiveness for the lack of any further photos.  
At this point in proceedings, my hands were so filthy that I didn’t dare try to take any more pictures lest I ruin my Blackberry.  The remainder of the job was completed without major incident.  I had to use the “hammer and drift” method to shorten my new chain to the correct length and did wonder how easy it would be to re-join a chain in this way.  I didn’t get to find out though as the new chain had an innovative kind of split link called a “Missing Link”.  It’s designed to be installed with the chain and then function as a normal link, the same as any other.  It’s not possible to split it again in order to remove the chain (I’ll need a new chain-breaker for that) but may also be a bit stronger.  Given that the only chain I’ve snapped in use broke at the split link, this may not be a bad thing.
And so I now have a smooth new drivetrain on my bike with a slightly increased set of gear ratios.  I’ve had a couple of weeks to get used to the changes but will put in a few more miles before writing up my thoughts.


  1. I've been looking for a folding bike blog that is on the technical side. I've been riding folding bikes for two years, but I am an idiot when my bikes get broken. Will visit this place some more.

  2. Hey thanks. :-) I'll try and keep it a bit more up to date!