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Chain Catcher

Posted: 27 Jan 2012, 4:42pm
by Mick F
MickFangStop (patents pending)

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! :D
Mk1.jpg
Mk1.jpg (32.53 KiB) Viewed 12962 times
Mk1 in position.jpg

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!
Rubber tubing .jpg
Mk2 in position.jpg
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.

Re: MickFangStop (patents pending)

Posted: 27 Jan 2012, 5:15pm
by Valbrona
I thought the Mr Heath Robinson of the Bicycle World said that he wouldn't use a chain catcher device?

Re: MickFangStop (patents pending)

Posted: 27 Jan 2012, 5:30pm
by donnieban
The mark 2 gets my vote. Simple but brilliant solution to a problem that most of us have experienced although some bikes/ drive trains appear more susceptible. In any case, oily fingers have a habit of fouling jackets.... I like the chrome/black look, and if the tubing is less than snug a zip tie will easily remedy.

Well done Mick.

Re: MickFangStop (patents pending)

Posted: 27 Jan 2012, 5:31pm
by hubgearfreak
Mick F wrote:I can cure the problem by changing


to hub gears, perhaps even to shimano :wink: ,

Re: MickFangStop (patents pending)

Posted: 27 Jan 2012, 9:03pm
by manybikes
hubgearfreak - you are a wag!
MickF - Are we to see an order form circulating soon?

Re: MickFangStop (patents pending)

Posted: 27 Jan 2012, 9:25pm
by PH
Mick F wrote:http://gvtc.com/~ngear/whatis.html Seems a good idea but has to come from USA.


For those without the time, parts bin or inclination, the Jump Stop is available in the UK, works perfectly, is adjustable, and costs around a tenner.
http://www.jdcycles.co.uk/products.php? ... 19s352p478

Details and instructions here;
http://gvtc.com/~ngear/instruct.html

Re: MickFangStop (patents pending)

Posted: 27 Jan 2012, 11:43pm
by reohn2
Mick F wrote:http://gvtc.com/~ngear/whatis.html Seems a good idea but has to come from USA.

Now c'mon Mick you know its because they're black not bling :roll:

PH wrote:[For those without the time, parts bin or inclination, the Jump Stop is available in the UK, works perfectly, is adjustable, and costs around a tenner.
http://www.jdcycles.co.uk/products.php? ... 19s352p478

Details and instructions here;
http://gvtc.com/~ngear/instruct.html


There speaks a wise man! :D

PS, Another source:- http://www.billys.co.uk/english/group.php?prod=chng-js

Re: MickFangStop (patents pending)

Posted: 27 Jan 2012, 11:47pm
by thirdcrank
Mick F wrote: ... it worked a teat! ....


:?

Re: MickFangStop (patents pending)

Posted: 28 Jan 2012, 8:38am
by Mick F
Oops - typo! :oops:
No matter how many times I read and re-read before pressing Submit, one typo will get through!

Thanks PH for your info. I thought somehow that it could be adjustable, I should have read further.
£9.99 (plus P+P?) is a better price than £7 for the Dog Fang, at least it looks like a good bit of kit and well designed.

My clamp is £4 odd from Ribble, and a bit of rubber tube costs about zero.
Mine is anodised alu.

Thanks for reading!

Re: MickFangStop (patents pending)

Posted: 28 Jan 2012, 9:13am
by Cunobelin
thirdcrank wrote:
Mick F wrote: ... it worked a teat! ....


:?


You're milking this for all it's worth aren't you?

Re: MickFangStop (patents pending)

Posted: 28 Jan 2012, 9:34am
by reohn2
thirdcrank wrote:
Mick F wrote: ... it worked a teat! ....


:?


Well he's been papping on about it long enough :)

Seriously Mick,if you look at the J/stop I'm sure you could make a plate similar to fit the f/mech hanger :wink:

PS I think you'll loose the rubber when the chain tries to derail.

Re: MickFangStop (patents pending)

Posted: 28 Jan 2012, 10:07am
by Redvee
Have you looked at the Token Chain Catchers?

http://www.chainreactioncycles.com/Mode ... elID=58049

Same basic design as the K-Edge chain catcher but leee hurt to the wallet.

Re: MickFangStop (patents pending)

Posted: 28 Jan 2012, 11:09am
by 531colin
A while back one of the regulars (Crepello?) posted an elegant, adjustable, chain stop device made from a bracket (I think the bracket was from SJSC) a nut, and a single Allen screw..
Unfortunately I can't find either the post or the bracket :oops:

Still, well done, Mick, for improving on Campagnolo's finest.

Re: MickFangStop (patents pending)

Posted: 28 Jan 2012, 12:46pm
by CREPELLO
531colin wrote:A while back one of the regulars (Crepello?) posted an elegant, adjustable, chain stop device...
Cheers Colin.

As an Alternative to the Mickfangstop, I give you the new improved Chain Check Mate :D
Chain-check-mate.jpg
The improvement is the addition of the penny washer, otherwise it just functioned as a chain catcher. At the moment it effectively nudges the chain back on the granny ring. It may be possible that the chain could get through the gap between the button head screw and chain ring. I will then try counter-sinking the washer for a CS screw. But at the moment I think the doom shape of the screw is probably helping the function of throwing the chain back in the right direction.

I have to say I'm a little surprised at Mick's solution. Not because it's similar to mine, but because it isn't so elegant looking for such a nice bike. I speak myself as an owner of a Mercian with the same problem (incidentally, it didn't have this problem until I changed the chain rings from the Campag 53/42/30 for 50/39/26). I'm reluctantly going to fit one of these devices, but if I had a braze-on front mech, I'd opt for one of those dangly things. Unfortunately, the Token Chain catcher linked by Redvee is spec'd for double chainsets. I doubt it would work for a triple. Does anyone know for sure?

I would even have a go at making one of the danglers from a 2mm thick spoke, doubled up (U) and bent to a similar shape. It should be possible to attach between the clamp and the screw holding on the mech. Whether it would be rigid enough to perform well enough, I don't know. If not, what about using a stainless steel mudguard stay? Could it be hammered out flat to drill out for the screw attachment? Just ideas...

Re: MickFangStop (patents pending)

Posted: 28 Jan 2012, 1:11pm
by Mick F
CREPELLO wrote:I have to say I'm a little surprised at Mick's solution. Not because it's similar to mine, but because it isn't so elegant looking for such a nice bike.
I agree.

If anyone can be bothered, they can search my posts on the subject and they will find that I don't want one at all, no matter what design or cost. I made the Mk1 and the Mk2 at no cost at all except some brain power. I admit it isn't a perfect answer, but as it matches the front mech's bracket, it isn't too bad.
Brackets.jpg


If the Jump Stop was more elegant and with anodised alu bracket instead of cheap black plastic, that would be the one to have. I will stay with the MickFangStop Mk2 for now, Mk3 isn't an impossibility.

For R2:
I deliberately mal-adjusted my front mech so the chain hit the split rubber tube during my initial testing period, and it didn't move one iota. If it had done, I'd have secured it with Bostick or similar, but as it didn't, I left it held on with friction. The rubber tube is a small length from a Topeak dual fitting head for a track pump and is quite sturdy.