[Closed] Double & bash shifting problem

adjust the cable tension until it does. its the cable tension that control the position of the cage for the middle ring and you will need to alter this as you have changed the size of the ring.

sometimes dropping the mech down the tube can help as well. Many of us run 2 ring setups with triple mechs - its not perfect but it works

I have recently done a similar thing i went from 1x9 to 2x9 as I have lent my Dad the HT, I used a 3 speed LH shifter and it works fine. Conventional style front mech which also was 3 speed, I just wound in the H limit screw and it works fine, I set the front mech so it just misses the Bash by a few mm. and then just set up as normal from there. It's been working great! Good chain lines and very little rub in any gears.

It takes a little practice but it should work just fine with a triple specific front mech. Unless the chainline has altered - ie you've installed a new BB and haven't fitted the correct number of spacers - then you shouldn't notice any difference with shifting.

There are double specific front mechs out there, but I suspect that the solution to the problem is a much cheaper fix with the cable routing.

3 speed mech here with 22/36 and no problems. I positioned the mech vertically as if the big ring was still there. Also try setting the L screw to get the correct low / resting position before you attach the cable.

Cable tension is fine. I'm only using my granny and middle positions on the shifter, so there is still the big ring position for any needed overshifting but it's not getting that far. I've also tried dropping the mech as far as it will go, until the bottom of the cage is about 1mm off the chain stay. I haven't set the H limit screw yet, I was going to do that once I got the chain on the middle ring.

The problem is that the inner cage plate bulges towards the middle ring then pulls away again near the (now removed) big ring. The bulge engages the chain on the the shifting ramps but just at the point where the it's about to engage the teeth it hits the bit where the cage widens, so the chain just bounces on top of the shifting ramps, in a position where it stops the cage moving any further, so I can't over shift 🙁

But this was the last part of the build late last night, on the workstand. I was just wondering whether it was a componentry issue or something I had to fettle to get right. At least I know it should work. I'll have to put some rubber on the wheels and have a 'ride up and down the street and fettle until it works'.

Cheers for the quick responce 🙂

mtfu and go 1x9 or 1x10

Check the position of the mech on the seat tube.

For a 36T it needs to be higher up the tube than a 32T.

Front mechs are designed around the middle ring position and are quite fussy about any size changes. I have a 20-32-42 that was just impossible to get working properly with an M760A designed for 22-32-44. In the end I went down-group to Deore, set it up for the 32 and all is OK, but not ideal getting up to the 42.

Good luck with anything outside the Shimano specs.

PaulD

greeble - I'm toying with the idea of building the old frame up as 1x10 but the baby that is due to arrive this week trumps a new drive train 😉

Cheers Paul, definitely going to play with the mech height and angle until it works.

greeble - I'm toying with the idea of building the old frame up as 1x10 but the baby that is due to arrive this week trumps a new drive train

keep it 1x9 and ride it as it is

I understand you can also get a double specific middle ring, (36T) from Shimano, what is the part number on yours I can check this with mine to see if there are some differences?
Thanks for the tip on raising the mech up the seat tube.
Richard

It should definitely work. The only slightly compounding factor is the slightly bigger jump from 22 to 36. But you shouldn't have to buy a different mech or anything.

As others have said - check the position on the seat- tube. I've always thought 'the lower the better' although the way you described the bulges it might make sense to move it up a cm or so.

Have you checked to make sure shifting pins on new 36 ring are aligned up correctly? (Not that I may have made that mistake when I changed mine). Went from 22-32 to 26-36 using same front derailleur, used H screw to prevent overshift; surprised me how quick it was to get up running with it (ignoring the error with the 36 ring that I didn't have).

move the mech up the ST. as said above you need to align it for the now bigger middle ring. HTH

I'll have a look into the double specific ring thing, although would that be because Shimano may have made the fittings for the double and triple SLX middle rings different so they weren't compatible (they've never done that sort of thin before, honest!!)

I'll have a play with the mech later and report back. At the moment I have been diverted onto last minute DIY and nursery prep, so I might not get it sorted for a while.

how did you get on?

Okay, it was my fault! Just glad everyone said it should work so I didn't go off on a tangent.

The issue was that my old frame (a PA that will get the TLC it needs and a rebuild in the future) was top pull and the Alpitude is bottom pull. With the gear cable threaded the other way, over the top of the mech, it naturally went down the groove on the left hand side of the cable clamp bolt. I then positioned the hook of the clamp horizontally, facing the frame (I hope my words are painting the right picture). What I didn't realise was as the clamp moved during shifting the cable clamp then fouled the main mech clamp, that attaches it to the frame, Doh!.

With a pair of fresh eyes this evening I found the issue very quickly. Once I repositioned the hook part of the cable clamp to face downwards the problem disappeared and the gears now work nicely 🙂

I still found I had to position the mech as high as it would go so I didn't get any chain rub.

Cheers for all the advice 🙂