Monday, 1 June 2015

Bit of service work on the bike

Can you see what is wrong?
I like to ride.
I don't much want to spend all my time fixing my bike, I want to spend all my time riding it!
Sometimes, though, a bit of maintenance is needed.
I have a "Century" ride coming up on Sunday, so I gave the bike a quick lookover last night.

oh-oh ...

The middle chainring

I had a "spare" in my parts box.
It is a little smaller, but a 34 (steel) with all the teeth is better than a 38 (alloy) with 3 teeth missing!

While it is all apart, I might as well change the 28-tooth "inner" for the 26-tooth one I have in my "spares" box.

All back together - a 48/34/26 set-up.
Not as evenly balanced as the 48/38/28 I was running before.
More of a "double" (48/34) with an "extra" (the 26)!

"Standard" hex wrench ("Allen key") compared with the same size from a bike kit.
The one from the bike kit has a MUCH longer handle.
This size is used for tightening up the cranks!

Cleaned it all up a bit and fitted a new chain while I was there.

Not sure if these "quick links" (aka "power links") are quite as strong as a "proper" link, but they sure speed up the process!
The chain I took off had a similar link, and showed no problems, despite the transmitted power being enough to break off three chainwheel teeth! (see top photo!)
And then onto the testing.
It didn't want to change into the lowest chainwheel.

The (broken) previous chainwheel has all those fancy pins and shaped teeth and all that (indeed, all three teeth that broke off did so at a point where the fancy shape made the metal thinner!)

The "spare" is just a plain steel ring from a "double".
The derailleur didn't want to go close enough to the frame to ensure the change, and the smaller middle ring (34 vs 38) mean that the chain was now touching a lower part of the front derailleur, which also has a fancy shape.

I guess the two chainwheels I replaced have a slightly different chainline!
And I guess all those fancy pins and shaped teeth made the changes MUCH smoother than the "plain" steel ring.

However, I can think of five solutions:
  1. Get exact replacement for the chainrings I had (!)
  2. Fit a slightly wider BB to move the rings out a bit (the front derailleur has loads of room left on the "high" stop, but none on the "low" - it goes to "slack cable" and still doesn't move far enough in!)
  3. Get a different derailleur with a more compact design that will move closer to the frame
  4. Leave off the inner ring, and just run it as a double, replacing the rear 11-32 cassette with a cassette that has a 36, giving me 34/36 as my lowest gear (I am used to using 28/32 for the "toughest" hill in my area, so I'm going to have to toughen up a bit!)
  5. Loosen the front derailler clamp and twist it so the bottom of the cage is closer to the frame.
I did number 5 - I rotated the derailleur a bit, so the rear is closer to the frame.

It now all works, but the front derailleur needs quite a bit of trimming!
Good job my front derailleur twist grip has 8 or 9 click "positions", rather than just 3!
Gear changing is very slow and clunky from the small ring to the middle and back.
In fact, It reminds me more of how things used to be before index shifting was invented!

Clearly, I am going to have a sort out a better answer in the future.
I will have a look at the chainline, and see if a wider BB is a sensible option (I have one quite a bit wider in my "spares" box).
I might invest in another 38 tooth chainwheel, too, with the pins and shaped teeth.
I found 38 to be a lovely size, and I used it for at least 90% of my cycling (which is why that one broke first!)

Importantly, though, the bike is good enough to ride on Sunday!

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