I'm thinking of reverting .....

[Steve Kish]

... to a left-hand thumbie.

This is because the front cage scrape I get with my Rapid-fire type left fixed position shifter is annoying me.

I've tried as best I can to adjust the cable but it either scrapes in the 32T or the 11T or if really done precisely, scrapes in both! :evil: Front mech is correctly adjusted for both angle and height.

Anyone else done this?

 

[legrandefromage]

what front mech?

 

[Steve Kish]

The one that shifts the chain between the chainrings. :roll:

 

[legrandefromage]

model!!!!!


Oh ffs, WHAT MODEL OF FRONT MECH?


some have wider cages than others which helps. Unless you dont want any help....

 

[xerxes]

I was thinking exactly the same.

The problem is, you're not really supposed to use all the rear sprockets with all the front chainrings. Using the outermost rear sprockets from the centre chainring causes the chain to curve sideways excessively and increase wear.

See the bit about chain line here: http://www.southcoastbikes.co.uk/articles.asp?article=Gears

The trouble is, there are a couple of "sweet spot" gears in the "not supposed to use" combination.

 

[velomaniac]

In the distant past and even today I replace the LH shifter with a thumbie for pretty much the same reason your thinking of plus I've never really liked indexing.

Sad old technophobe that I am

 

[Steve Kish]

Unless you dont want any help....

Well, so much for the helpful attitude!!!

Lighten up, chap! I don't need a tutorial about adjusting front mechs. My question just asks if anyone uses a thumbie shifter for this!

FWIW, front and rear mech are both LX Deore and the problem is with the middle ring of a White Industries chainset, which aligns with the middle two sprockets on my 8-speed cassette. With such alignment, I'd expect all 8 gears in this ring to be scrape-free.

Big ring only ever used on smallest 6 sprockets and small ring with the largest 5 sprockets. Chainline is not an issue.

 

[legrandefromage]

Unless you dont want any help....

Well, so much for the helpful attitude!!!

Lighten up, chap! I don't need a tutorial about adjusting front mechs. My question just asks if anyone uses a thumbie shifter for this!

FWIW, front and rear mech are both LX Deore and the problem is with the middle ring of a White Industries chainset, which aligns with the middle two sprockets on my 8-speed cassette.

Big ring only ever used on smallest 6 sprockets and small ring with the largest 5 sprockets. Chainline is not an issue.

Some front mechs have a narrow width cage which buggers up any hope of using STi without the continual 'clac clac clac' chatter.

I was going to advise a change of front mech, but.... its my attitude, it wont let me.



You actually had my sympathy, STI and front mechs really is a black art and even when all the supposedly correct parts are together, its 'clac, clac clac'.

Its why I have thumbies on the GT instead of the Rapid Fire PLus it should have.

 

[dan_b]

I have had the same problem a few times over the years, recently I used a FD-M651 (Sprung brace mech) on my Scott Evo rebuild. Not only did this scratch my new paint (not happy) but I adjusted it 10-15 times and it drove me round the bend. I bought a M736 clamp front mech (from here) and I have put this on and I have adjusted this once and it is a sweet as a nut... I hate mechs that rub...

Ta,

 

[Steve Kish]

FWIW, the shape of the cage seems to indicate that it's made for a much bigger ring. The curvature of the cage is a lot shallower than the curvature of the outer (42T) ring.

I have thought about bending it for a more uniform distance between the teeth and the big ring all the way along but as it's a Deore one made for outer rings about 42-44T rather than summat like an Ultegra for 53T, I figured that it's supposed to be like this.

Also, if I tweak the tension of the cable so that middle ring has no scrape in the 11T, it tends to dislike being dropped into the smallest chainwheel.

Mp3 player with tight fitting lug-plugs helps a bit!