As I'm sure many of you know, I have been experimenting and testing to find out why my front gear changing sometimes results in an unshipped chain when going from middle to inner.
I proved - at least I'm convinced - that the problem is that the chainset flexes under load and this is exacerbated by the frame flexing too. I can cure the problem by changing gear VERY sensitively by allowing the cranks to rotate one whole revolution before the ring change to allow the chainset and frame to "relax". This seems to have worked 100% but is a little boring and slow when I want to push on - or if I get caught out needing a quick gear change.
Now I know what the problem is, I've set my mind on producing a device. I didn't want any of the equipment on the market:
http://www.ctcshop.org.uk/k-edge-chain-catcher/ Way too expensive!
http://gvtc.com/~ngear/whatis.html Seems a good idea but has to come from USA.
http://www.ctcshop.org.uk/deda-dog-fang/ Seems a good idea too but is plain old black plastic. £7 for a bit of plastic?
These things must work a treat, but I had some misgivings. The Chain Catcher is adjustable but the Dog Fang isn't. It isn't clear about the Jump Stop but it doesn't look like it will be. Surely, all chainsets and BBs aren't equal, so Q factor must vary, therefore these devices should be adjustable in and out?
Also, they are black (or brightly coloured) and not shiny standard anodised alu. Why not?
Firstly, I got out my collection of Cateye lamp brackets and found one with the correct diameter for my seat tube. Actually, it was a little loose, so I stuck in a piece of inner tube. I used a bit of SS from an old mudguard bracket, then bent it at right angles. I rubbed down the bracket and pained it with primer ready to spray it with chrome paint.
I fitted it and tested it. After adjustment and fine tuning, it worked a teat!

I was happy with the operation and I had 100% good gear changes no matter how badly I changed gear.
However, I wasn't happy with the look of it. Heath Robinson sprung to mind. So I set about thinking again.
I have a spare one of these:
http://www.ribblecycles.co.uk/sp/road-t ... SNAGRSZ200
but the derailleur attachment flange wasn't stuck out far enough and the curve on it wasn't conducive to bolt a bent bit of metal to it neatly, so I carried on thinking for a few days.
Then it struck me!
A bit of rubber tube!
The clamp went on easily - and matched the front mech's clamp - and the tubing didn't look too bad at all. I was pleased, but I'm on the lookout for some clear tubing of the correct thickness instead of black. Meanwhile, this'll do nicely.
Out on the road, this Mk2 version was brilliant. Mk1 had to be positioned very accurately up and down and in and out whereas Mk2 has a long front so it's not too fussy up and down, and the whole thing can be rotated for correct adjustment in and out.
Long-term test is now in progress.