Is my mech bent?
 

[Closed] Is my mech bent?

Posts: 3135
Full Member
Topic starter
 

Thought I'd bent my mech cage and/or hanger. Straightened the hanger, but it looks like the surface that mates with the hanger and the surface that mates with the cage are not coplanar (to use the fancy word).

So the mech body itself must be bent right? They're not meant to be like that, Shirley?

It seems improbable though, since the body is all solid bits of cast aluminium and there's no obvious bending.

Parallelogram still operates smoothly. It's a Deore mech in case it's relevant.

EDIT: Obviously you've no idea if my mech is bent if I don't post the pictures I took of it:

[url= https://c1.staticflickr.com/4/3839/33364315945_415ec9b57c_b.jp g" target="_blank">https://c1.staticflickr.com/4/3839/33364315945_415ec9b57c_b.jp g"/> [/img][/url][url= https://flic.kr/p/SQhQJD ]2017-03-10 20.27.21[/url] by [url= https://www.flickr.com/photos/136120472@N08/ ]Dave W[/url], on Flickr

[url= https://c1.staticflickr.com/4/3945/33364317165_f19ea4a315_b.jp g" target="_blank">https://c1.staticflickr.com/4/3945/33364317165_f19ea4a315_b.jp g"/> [/img][/url][url= https://flic.kr/p/SQhR6F ]2017-03-10 20.26.58[/url] by [url= https://www.flickr.com/photos/136120472@N08/ ]Dave W[/url], on Flickr


 
Posted : 10/03/2017 9:38 pm
Posts: 0
Free Member
 

I'm not quite sure what the problem is. Are the jockey wheels not parallel with the cassette sprockets ? Is you gear indexing not good any more ?


 
Posted : 11/03/2017 12:25 am
Posts: 3135
Full Member
Topic starter
 

Yup, jockey wheels are way off parallel with the cassette and shifting is sluggish, sometimes non-existent (particularly up) despite good cable.

In the top pic, the cage is sat on a flat desk but the hanger stud is at an angle. In the bottom pic, the hanger stud is horizontal, but the cage is not vertical.


 
Posted : 11/03/2017 8:34 am
Posts: 0
Free Member
 

Looks bent.


 
Posted : 11/03/2017 8:54 am
Posts: 17771
Full Member
 

Looks like the Parallelogram could be bent.
In your first pic the paint is missing from it to the right of the pivot point.
I'd look closer at that.


 
Posted : 11/03/2017 9:21 am
Posts: 3135
Full Member
Topic starter
 

Looks like the Parallelogram could be bent.

I think you're right. Been staring at it from every angle and not noticed, and you got it from a photo ๐Ÿ˜ณ

I was struggling to see a weak point but I think the pressed metal backplate of the parallelogram is it.

Ta.


 
Posted : 11/03/2017 4:52 pm
Posts: 41395
Free Member
 

It's not uncommon for the mech to bend.

You can try to bend? the plate to compensate but its probably a goner.


 
Posted : 11/03/2017 4:58 pm
Posts: 17771
Full Member
 

Been staring at it from every angle and not noticed, and you got it from a photo

Often all it takes is someone else to have a quick look that has no preconceptions of the problem to pick up the fault.


 
Posted : 11/03/2017 5:33 pm
Posts: 3135
Full Member
Topic starter
 

With judicious use of a fortunately-shaped vee-block, a 6" vice and a pair of mole-grips (all tools of the precision engineer, I'm sure you'll agree), I managed to bend it back near enough straight.

[url= https://c1.staticflickr.com/4/3681/33022296340_59fcb73195_c.jp g" target="_blank">https://c1.staticflickr.com/4/3681/33022296340_59fcb73195_c.jp g"/> [/img][/url][url= https://flic.kr/p/Sj4UdU ]2017-03-12 13.00.09[/url] by [url= https://www.flickr.com/photos/136120472@N08/ ]Dave W[/url], on Flickr


 
Posted : 12/03/2017 10:57 pm
Posts: 41395
Free Member
 

Chapeau.

Any time I've tried that it's been buggered


 
Posted : 12/03/2017 10:59 pm
Posts: 7996
Full Member
 

Any time I've tried that it's been buggered

Yes but at least you didn't find out you'd weakened it to the point of imminent failure halfway up some hill 20miles from home...but I'm sure that won't happen to the op....probably.

Good skills straightening it without snapping though. I've snapped all but one that I have bent back (or tried to) over the years.


 
Posted : 13/03/2017 8:58 am
Posts: 3135
Full Member
Topic starter
 

Why thank you.

Since it's the steel bit I'm bending rather than the ali, I'm reasonably confident that won't happen. Still, I've always wanted to try singlepseeding ๐Ÿ˜‰


 
Posted : 13/03/2017 4:43 pm