Mechanics and Fixing Any Questions Answered

Size of it

1 Attachment

Small hands or big tool?

Good question, here’s a banana for scale

1 Attachment

Shimano GRX 810...

Front shift has become so heavy as to often need two hands to shift up to the big ring. Changed outer, cable and removed and cleaned out the mech. Cable and shifter move freely when unattached to the mech. It just seems like the spring is now too strong/stiff for the leverage system.

Next to the GRX 600 front mech on my other bike its night and day. There is only so much dismantling that can be done with it to clean everything out but a thorough lube resulted in no change.

£31 for new one.....or am I missing something simple?

Any tight bends in the cable?

Sounds like there's some gunk in the FD or the cable wrap is wonk.

didn't spot that one, thanks! (I mean, it's still only one tyre, but at least there is one)

no problem at all (I'm not in the UK anyway, should've mentioned) - your link got me a Schwalbe model I can order locally, so all good :)

Set up properly? The limit screws can interfere with the mech if you try to do it like a traditional one.

Fuck it all, I stripped the shifter again. Fuck bikes altogether. Goodbye forever.

EDIT: I assume this will work as normal as a rear brake lever and front mech shifter....as I'll just add it to the existing hose for the rear? I dont trust myself with anything now.

1 Attachment

Ha yes did way too much googling in advance of trying the actual repair, but appreciate the pointer regardless. Starting with NDS regular right hand threaded at any rate!

Will try again stepping on the 32mm spanner with a headset cap and bolt through the tool and hope for the best. Should I install the new BB the same way? Do the cranks need to go on with equal leverage (I have one of those T-shaped 6mm allen keys with an 8mm attachment..)? Am supposed to be taking a long ride over the weekend and now unsure if I am willing to trust my own handiwork.. but will get the BB off first then see!

@MCamb we need to know the size of your banana for any proper understanding of this situation..

I know the answer, but why are the threads in a BB the opposite direction to the threads on the pedals¿ It used to really play with my head.

Explained nicely on sheldon brown iirc

I'll give the shop a 2nd chance.

Back to my initial comment few pages back, I suspect it's a UN300 which I've seen fail prematurely.

I’ve worked on a bike with this issue. Cables and housing are perfect, shifter works fine.

It all worked perfectly until the bike was used on long gravel rides, then it needed two hands to shift. Copious wd40 in the front derailleur corrected it the first time; the second time I only had a chance to add a few squirts of wd40, which improved it but didn’t get back to 100%. I think it’s grit built up in the front derailleur hinges, and possibly in the exposed housing hole near the rear wheel.

Yep that’s the shifter you’d want. If you’d like a second pair of eyes/hands to work on that first shifter, drop me a line.

Usually it's too much tension on the cable and the derailleur pushing against the limit screws. Try moving the outer limit, see if it improves

This got significantly worse after hours and hours.....and hours of torrential rain.

All good information, ta. I had it off the bike, WD40'd, cleaned out as best I can.

Thanks for the offer but I've done exactly this thing before, trying to work the shifter and pushed too hard and stripped the inside. Looks like Merlin will replace under warranty...again. They have categorically said there wont be a third time.

For the sake of not destroying another shifter and getting to the bottom of it once and for all, I've ordered a new one. £31 and hopefully its solved....until the next time.

So in the set up process, if I manually pull the cable too tight before nipping up the retaining bolt, it could cause this issue?

GRX (and most modern Shimano road) mechs aren't set up like older mechs, you set the cable tension first in the trim down from big ring to line up the two lines on the mech, then set the limits, the H limit pushes the mech out further, it's not a limit in the traditional sense. Read up on the instructions, if you try and set them up old style the limits can interfere with them working properly which I suspect is what you may have done.

Only issue I see with that explanation (which I’ve also seen happen) is that the shifting would’ve been problematic from the start, whereas Stoo61’s m was shifting well initially and deteriorated.

Because, somewhat counterintuitively, the pedals turn in the opposite direction to the cranks. Pedals turn backwards. That's why your foot stays on top.

How can I make this cable end nice without cutting it?

Don’t loosen the pinch bolt. Twist it with your fingers in the direction of the original twist. The wires will eventually settle as close as they can to their original positions. Add super glue, steel putty, or cable crimp.