Monday, September 14, 2015

Taking up the Slack

A bit on the tight side

Subtitle: Taking up the Slack from the Chain




I know,  just when you thought Agata's bicycle couldn't possibly get another upgrade,  Agata pointed out to me that on the small chainwheel at the front driving the largest gear at the back the chain was a bit loose as can be seen above.

What we neglected to discuss to our mutual error (until afterwards) was that this was a gear she never uses .....



And so we resolved to partake in a little chain shortening surgery.




We have this competent chain tool that actually holds the chain in place whilst you push the pins out.  Once the top is closed the chain is locked in place

We pushed out the pin to disconnect the chain and then did it in a second place to remove just 2 links, which is the minimum.


Oh, we consulted the 7901 fitting guide.  Read it for yourself and just when you think you have understood the benefits of A over B, ask yourself is that on the top side of the chain or the bottom.  Hmm


From a new an unused Dura Ace 7901 chain I borrowed one of the 2 special connecting pins.



Now this spare chain is our backout plan.  Obviously always have a spare chain, well in Switzerland I'd have no idea where to get one from quickly even at double-plus Swiss expensive prices.




Okay the connecting pin went in like a hot knife thru butter.  I did not recall that from my last chain fiddling some months back.




Now use the chain tool to push the link right through. It sort of goes easy then hard, at which point you stop.



Now the special link is in and according to the manual just break off the excess with some pliers.



 I can honestly assure you this does not work!


So using what I can only describe as the worlds bluntest saw, and considerable time later I cut thru the extra pin and then had to file the edge smooth.



Angle of the rear mech (derailleur) is acceptable but NOT in all cases



Do you see the issue?   On the large front chainwheel driving the largest rear gear, the d√©railleur is pretty close to horizontal!

Agata tells me this is a gear she does use all the time to move away from traffic lights.  Ooops.

Both this gear, max tension, and the initial case, least tension & maximum slack are extreme gear positions.  And personally, I'd never use those rations except in an emergency.  But Agata has reasonably replied, that before my meddling, she used that Big to Big combination all the time, and now it looks a bit dodgy.

So we'll have to do some more testing on the road to see that nothing falls apart, and the backout plan is to fit a new and 2 links longer (!!) 7901 Dura Ace chain.