rear mech issue/question

[gairym]

evening folks,

yesterday i received the final piece needed to convert my SS into a 1x9 and have now put everything together and set it all up.

but.....i've hit a bit of a problem.

even with the H barrel adjuster all the way out the chain keeps catching the next cog on the cassette (under zero tension).

the mech, cables (inner and outer), chain, cassette and shifter are all new and so surely it can mean only one thing???

the hanger must be bent - no?

now the hanger is not replaceable on an on-one inbred but it is reasonably bendable.

can you think of anything i may have missed before i start messing about with bending irreplaceable hangers and potentially ruining my frame?

any help/advice appreciated.

gairy.

[touch]

even with the H barrel adjuster all the way out the chain keeps catching the next cog on the cassette (under zero tension).

In every gear or only the bottom one?

Does an inbred have slot dropouts? If so, maybe the wheel (and therefor the cassette) is not parrallel with the frame?

Cant really think of anything else :(

[gairym]

it only catches in the bottom gear but it feels a little less than smooth all the way through the gears too???

at the front i've got the chain on a Surly 32T (SS) chainring (in the middle ring position) with a chain-guard and a jump-stop device so there shouldn't be any issues 'up front' that u cab think would be affecting things.

and no - it's not a sliding drop-out.

hmmmmm....?

[Ray Young]

Is the cassette lockring done up tight or is the b screw adjuster wrongly set?

[gairym]

will check both those things (although i'm sure they're ok) and report back in a few minutes.....

[Ian]

Is the chainring running a bit too in-board in relation to the rear? Longer axle on BB (if square taper), or check plastic spacers if integrated.

can you think of anything i may have missed before i start messing about with bending irreplaceable hangers and potentially ruining my frame?

Convert it back to SS?

[gairym]

Is the cassette lockring done up tight or is the b screw adjuster wrongly set?

the cassette lockring is all good and the b screw adjuster is as it should be according to advice i was given (6mm gap between sprocket and cassette cog whilst in 2nd gear).

Is the chainring running a bit too in-board in relation to the rear? Longer axle on BB (if square taper), or check plastic spacers if integrated.

the chainring is roughly in line with 6th gear on the cassette (1st being easiest) and so logically it should be having trouble when under tension at the other end of the cassette if it were the alignment - no?

i'm stumped!

[Bearbonesnorm]

*LONGSHOT*

The mech is free to move fully? I've had the odd one (even from new) that was a little tight. When it's in position of the smallest cog there really isn't much spring tension left, so any binding on the mounting bolt or pivots can stop it dropping home fully.

[Anthony]

I really wouldn't stress about bending the hanger straight. Steel frames don't generally get fitted with replaceable hangers because the steel is far more resiliant to being bent back into shape after a knock. A decent wokshop should have a tool that can check it is in alignment and will bend it back into shape, it's a 5 min job.

For years manufactures drilled into us that you need to split gearing: using the smallest chainring for the upper cassette, middle for middle and outer-ring to the lower end to over over stressing the chain. By fitting 1x9 your pushing the limits for how the cassette was originally designed to work. It sounds to me like the chain is being dragged across the next cog up and because of the nature of the shift ramps it's trying to change gear by itself.

It's one of the reasons why I prefer to remove the 2 loose cogs, and run just 7 cogs spaced to sit centrally on the freehub. I find it gives a reasonable chainline in all gears.

[gairym]

The mech is free to move fully? I've had the odd one (even from new) that was a little tight. When it's in position of the smallest cog there really isn't much spring tension left, so any binding on the mounting bolt or pivots can stop it dropping home fully.

seems to be free enough to move.

here's a photograph where it appears to me that the whole mech is twisted a little from being perfectly aligned with the cassette/chain-line:

http://simple-lodge.com/wp-content/uplo ... r-mech.jpg

(i put it as a link instead of an image as it's BIG)

what do we think???

[Anthony]

Oh, and it does it on the lower cog because it is being dragged across one that is slightly larger, so the teeth protrude out and catch into the chain. On the largest cog, it is being dragged across one that is smaller, so it has nothing to catch on.

Difficult to describe but hopefully you catch my drift :!:

[Anthony]

Oops, posting overlap!

Yup it does look twisted but sometimes the angle of a camera will just do that anyway.

The face of the hanger, should be perfectly inline to the wheel rim in all 360'.

[gairym]

Oh, and it does it on the lower cog because it is being dragged across one that is slightly larger, so the teeth protrude out and catch into the chain. On the largest cog, it is being dragged across one that is smaller, so it has nothing to catch on.

that makes perfect sense!

It's one of the reasons why I prefer to remove the 2 loose cogs, and run just 7 cogs spaced to sit centrally on the freehub. I find it gives a reasonable chainline in all gears.

that makes sense too.

i could remove the 12T smallest removable cog (as it's a Deore 12-36T and only one is detachable) but then my shifter would pop off one end or the other - no?

[gairym]

yep - mucho overlap.....

Yup it does look twisted but sometimes the angle of a camera will just do that anyway.

that is how it looks to the naked eye - think i might attempt a home-twisteroo and see if it comes off in my hand.

any advice on unbending technique anyone???

[Anthony]

You'll probably be needing a larger lock-ring, Token make a nice one that will cope and some spacers to replace the missing cog/s. I use singlespeed spacers.

You need to adjust the high and low screws to the remaining gears, so the spare 'click' is at the top (largest cog) end. The mech stop screw (low) will prevent the mech from engaging the last click, so it will feel like normal.

You could try just setting it up with the stop screws to avoid it dropping onto the 11t. If this works, then look at removing it and replacing it with a spacer.

To bend hanger - remove mech and clamp a large adjustable spanner on the hanger. Gently gently.

[gairym]

ok, here's the plan.....

i'll try bending the hanger (in the morning when there's more light) and then if that doesn't solve the problem i think i'll try and convert my recently converted 1x9 into a 1x8 and see if that fixes things.

thanks all for taking the time to assist me on this one - i've never been the happiest at setting up rear mechs. almost anything else bike-related i can usually fettle into shape but rear mechs are kind of my kryptonite.

cheers, gairy.

[Anthony]

Nah, it's front mechs that 'were' the black-magic.

Hope you get it sorted.

[gairym]

morning all,

after some minor tweaking and a little persuasion it seems like the hanger has been bent back to something nearing the correct position.

i've got to wait until the snow goes a bit before i can get it out for a proper test but i'm hopeful that we're back in business.

thanks again for all the advice.

gairy.