Is the cage on a Shimano 105 R7000 rear mech bent by design?

[Xipe Totec]

Eh up, long time no post!

Swapping out the Chinese tat groupset on my silly lockdown Ti build for the Groupset Of The People, now parts availability & prices of obsolete-ish groupsets have normalised.

All going nicely, I'm fitting the rear mech & lining it up by hand to set the limit screws when my eagle eye is drawn to this:

Doesn't look right at all. Both cage plates appear bent outwards, the jockeys don't align & actually appear to be twisted horizontally.

This kit is all brand-new, the mech hadn't been out of its little plastic bag before yesterday so the likelihood of it having been damaged seems minimal - and if it was made like that (and isn't meant to be) it seems unlikely that it'd get through Shimano quality control.

So I have perused t'web for other examples of curvy R7000 mechs - and sure enough I have found a couple of wonky ones, although none look quite as overt as mine. I can't find a direct reference to this being a design feature so I'd be grateful if any other R7000 owners would have a look at theirs & reassure me that it is supposed to look like someone reversed over it.

Or not...

 

[Drago]

Yes.

 

[Dogtrousers]

I think so, yes. Here's a terrible picture of a brand new, never installed, one. It's definitely got a kind of wiggly organic aesthetic. I might have a go at some better pics tomorrow in the light.

 

[Person]

I bought a shimano 105 r7000 RD about a year ago and it has a slight bend which works fine. Last October I bought a Boardman slr 8.9 carbon and the 105 RD is much more bent, the same as in your pics. At first I thought someone had bent it on purpose. Two different RD's bent to different points.

 

[Xipe Totec]

Cheers @Dogtrousers @Person (and @Drago - just so's you don't feel left out ) - odd, but sort of reassuring!

Will nail it on & see if it works. Just seems really strange, although tech moves in peculiar directions - like, we all grew up thinking skinny 19mm tyres were fastest, yet now all the pros are bouncing around on 28s & 32s. Similarly, maybe a consistent chainline through the jockeys is inefficient or shifts less well, counterintuitive as that might seem!

 

[All uphill]

Interesting.

My theory, based on nothing much, is that the RD is bent to bias it towards gear changes to a larger cog - the more difficult change.

It's more difficult for two reasons; it is moving against the in-out spring action of the rd pantograph which biases to a smaller cog ( as seen when a cable breaks) and against the spring that maintains chain tension.

If I am correct the outcome is easier downchanges to a bigger cog.

 

[Xipe Totec]

Update - it's all glued together now, rear mech seems to work absolutely fine, at least in the safety of the garage - apart from a small intermittent niggle with the shifter occasionally 'forgetting' how to shift back up to higher gears - the inner paddle loses its clicky action & goes slack. I suspect it's just overzealous application of that sticky, radioactive green glue-grease muck Shimano like to glob all over anything that moves. It'll probably calm down in time. Hopefully.

In other news - that R7000 front mech is sh!te - incredibly, pointlessly fiddly to set up & despite following the instructions to the letter, I still can't get it to run without rubbing in certain gear combinations. All thanks to an internal cable tension adjuster which is apparently meant to be 'better' than a barrel adjuster. Amazingly functionless example of a solution in search of a (non-existent) problem!

Anyway - tomorrow I'll bleed the brakes, tighten everything up proper, re-tape the bars, & in the unlikely event it stops bloody raining, see if it all actually works!

 

[StuAff]

The only minor issues I've had with R7000 on the Tripster (in lots of miles since July) were both with the FD: that rubber link cover decided to work its way loose (and it's ridiculously hard- or at least it seemed that way by the roadside in a village- to get back in place), and the other week shifting suddenly became recalcitrant & I thought I was stuck on the inner ring, though it would shift in the middle of the cassette. Fortunately, I knew there was a good LBS just up the road- not even slightly off-route- and they sorted it there and then. Otherwise, both front and rear have been faultless, even in the 'wrong' gears, a quick trim all that's been needed. Hope you can get it sorted without resort to an LBS or violence.
A quick google found this which might help.... [https://bicycles.stackexchange.com/questions/87092/shimano-105-r7000-front-derailleur-setup-new-bike

 

[Xipe Totec]

A quick google found this which might help.... [https://bicycles.stackexchange.com/questions/87092/shimano-105-r7000-front-derailleur-setup-new-bike

Thanks for that - I hadn't been adjusting the H limit screw in the big/big/trim position, so that's where I might have gone wrong. Got everything else right by the book (although it's a bugger to get & keep tension in the cable before tightening the cable pinch bolt) so I'm faintly hopeful that might sort it!

And if the worst comes to the worst an old 5700 front mech's only about £20.

 

[Xipe Totec]

Update - bike's all back together and running sweetly. Looks like I had been adjusting the front mech in the wrong RD position, as there's no rubbing anywhere now.

I still fail to understand the reason for the FD redesign - it doesn't change any more smoothly or accurately than the previous generation did when properly set up (comparing with Ultegra 6800 on one of my other bikes) and the lever action's much stiffer. On the other hand, the rear mech's lovely, very slick & accurate with a noticeably lighter/quicker action than other Shimano RDs I've used. So maybe they're on to something with that Banana Cage concept...

Next job will be working out how to fix the constant lever rattling any time you're not on the hoods!