Saturday, April 05, 2014

Agata gets into a new Gear



Let us face facts.  Lausanne Switzerland is built on the side of a mountain.

From lakeside  (Agata's work) to home it is a climb of over 400 metres.

And so  Marcus agreed that her currently difficultly geared bicycle needed changing. 



Marcus's first plan was to change out the existing Shimano Dura Ace block for a new ultra lightweight  titanium or above aluminium block.

In general a Dura Ace 7900 block is about 170 grams (100GBP)

A titanium single piece block might be about 120 grams (200GBP+)

And the above Aluminium block is about 105 grams (90GBP)

A /regular/ Shimano 105, 10 speed block weighs about 250 grams (20 GBP)

Search as I might I could not find any titanium block, and with all due respect to Agata I thought that an Aluminium block might be too fragile:  The user manual cautions against changing gear at low revolutions for fear of breaking off teeth!

So I went with the Dura Ace Cassette which is currently on sale at Wiggle.  So it cost just 100GBP + 8% duty + 15 CHF inspection fee.

Aside:  The 7900 series 10 speed  Shimano Groupset is now replaced by the 11 speed 9000 series. If only Shimano had stuck with 10 gears.  Who needs 11 gears!  It is ridiculous. Anyway, flame off, and to continue ...




Removing the old block was easy, (though oily) as I have a cassette removal whip


The cassette is a set of individual parts that slot together. The spline is suitably keyed so you can't mis align.

(Note: The older English term for cassette is Block, presumably a name to represent the fact that in earlier days this really was  a single piece part.  Modern /cassettes/ are named I suppose because they are made from a set of interlocking cogs, a cassette which slots together in fact.)


That was the easy part


Getting the chain off with a special tool was also easy.   Of course when changing cassette the wisdom is to ALWAYS also change the chain  (and some even say front chainwheel!)




First I noticed that the Dura Ace chain is directional and then I began to wonder why I never noticed this on the last 2 chains I fitted.  Oops!

Next,  I made this new chain exactly the same length as the old one, having first tried the new wheel/cassette with the old chain to make 100% sure that the slighty larger cassette diameters did not require an extra chain link.

So I had to remove 8 links ....   Initially I got the wrong end and then reverting it back which meant 1 stiff link.  And by the time I joined up the chain .. 2 stiff links.

A lot of fiddling, pin in a bit, pin out a bit later ... it was a little better but by no means perfect.



Still here is the finished result.

Test cycle in the garage OK

20Km cycle to work and back up steep hills for Agata ... OKay
Saturday afternoon pootle .. just fine


Seems like the 2 moderately stiff links are getting looser and there will be no stopping Agata now.    39 front tooth chainwheel and 28 teeth cassette at the back.  She will be flying up those mountains near and far.   Marcus will have to get fitter just to keep up.