Indexing Your Gears Is a Compromise Rather Than An Absolute.

[Ajax Bay]

The point of this thread is to illustrate the fact that I've spent may [sic] hours trying to get my gears indexing perfectly and I've not been able to, despite all the advice from CycleChatters.

FTFY
People have made it clear that there 'absolutely' IS such a thing as a perfect set up. The only person that you will persuade otherwise
is you, seeking an excuse to 'compromise'.

 

[Chislenko]

My Mike and Bernie bike is a 3 X 8 and changes perfectly.

Dusted down my Donna bike yesterday for its first ride in six months (2x11) and the changing was all over the place. Two minutes in the stand and a tweek on the barrel adjuster and Robert was my relation.

Like others have said if you can't get it right something else is in play.

 

[Lovacott]

FTFY
People have made it clear that there 'absolutely' IS such a thing as a perfect set up. The only person that you will persuade otherwise
is you, seeking an excuse to 'compromise'.

If you ride a triple every day over hill and vale, you'll soon notice that there is no such thing as perfection.

You'll get sweet changes if you are on the middle ring at the front, but on the big ring or small ring, you will get a stutter at the back either up or down depending on the level of cable tension on the rear mech.

My bias is towards quick changes down which is literally less than a quarter of a turn of the barrel adjuster away from quick changes up.

For me, it's preferable to have quick changes down on the up hill sections which means I compromise with slower changes up on the flats.

 

[Lovacott]

My Mike and Bernie bike is a 3 X 8 and changes perfectly.
Like others have said if you can't get it right something else is in play.

The more you ride a bike, the more you notice.

When I'm doing a 1 in 5 ascent, I want the changes down to be instant so that I can carry on with the pedals and keep up momentum.

To get quick changes down, you need a slightly slacker rear mech cable which in turn will make your changes up a bit hesitant.

On a triple, there are only a few positions where the chain is straight with the rest of the gears placing the chain on an angle between the crank sprockets and freewheel. Therefore, it's physically impossible to get a 3 x 7 to work perfectly in every gear.

Everyone seems to acknowledge the fact that big to big or small to small doesn't work, so it's logical that some of the changes in between will be biased to a quick up or down depending on the level of cable tension applied to the rear mech.

 

[Foghat]

Like others have said if you can't get it right something else is in play.

Indeed. It's not difficult getting indexing to work really well across all the gears (although of course actually using small-small or big-big, especially on a triple, is daft).

I've never had any indexing problems over many years running various hard-used triple and double set-ups. And I've cured plenty of other people's indexing difficulties, and have found that when they complain good indexing across the range is not happening, it will be down to one or more of the following:

• bent hanger
• fraying inner cable
• stiff-action cable due to corrosion and/or lack of lubrication or kinked cable-run
• inner cable fastened on wrong side of pinch-bolt
• derailleur adjustment screws not set properly
• damaged derailleur
• severely worn or loose jockey wheel(s)
• loose cassette lockring
• incorrect cassette sprocket spacers
• clapped-out shifter
• mechanical ineptitude with the barrel adjuster

 

[HobbesOnTour]

This is the longest running April Fool's thread I've seen! Well done to the OP!

 

[Twilkes]

On a triple, there are only a few positions where the chain is straight with the rest of the gears placing the chain on an angle between the crank sprockets and freewheel. Therefore, it's physically impossible to get a 3 x 7 to work perfectly in every gear.

The shifts don't happen on the top part of the chain which is under tension between the cassette and the chainrings, they commence underneath with the part of the chain that has variable tension due to the sprung derailleur cage. Part of the job of a (correctly aligned) derailleur cage is to supply the chain perfectly parallel to the sprockets, so it doesn't matter what angle the rest of the chain is.

You can see it in this image - the top jockey wheel is perfectly below the sprocket, even though the top of the chain is coming off that sprocket at an angle:

If anything it's best to err on the side of having the derailleur slightly too far to the right, as you can always 'overshift' to the bigger sprockets by pushing the shifter slightly more than necessary to get it to move up the cassette, whereas shifting to the smaller sprockets is solely down to how much cable the indexing in the shifter releases.

When people say that big-big and small-small isn't recommended it's due to possible extra wear on the chain or rubbing on the chainrings/front derailleur, nothing to do with rear shifting.

You don't appear to be listening though so instead here's a nice picture of a lovely teddy bear:

 

[Drago]

I don't know about triples but my Chorus 11sp just works perfectly every time.

Indeedy. All my bikes bar one shift cleanly and crisply, up and down the cogs. The exception os my Subway E - its still pretty good, but the all plastic Altus mech has just enough inherent flex that I can never get a perfect set up.

 

[Lovacott]

You don't appear to be listening though so instead here's a nice picture of a lovely teddy bear:

That's a tad rude if you don't mind me saying.

My rear mech is perfectly aligned and my indexing is very good. It's actually better than new.

But my changes up are slower than my changes down and if I tension the barrel adjuster just a quarter of a turn, my changes down get too slow.

It's more important for me to have quick down changes so that I don't lose momentum on uphill stretches.

I don't mind the slower up changes because I'm only changing up when the going is getting easier.

Like I said in the OP, it's a compromise.

 

[IanSmithCSE]

Good morning,

I think that I understand the OP's point but the title may be misleading.

If I read the posts correctly the OP is deliberately incorrectly setting up the indexing so that instead of the pulley/jockey wheels being directly below the selected sprocket they are offset towards the next larger sprocket.

Almost a "partial preselect" of the next downshift, doing this would lead to a faster downshift as there is less movement of the rear mech to complete this "partial preselect". The downside of course being that the rear mech doesn't move far enough on the upshifts to allow for a proper change.

However as this "partial preselect" alignment is outside of the intentions of the designers of the system it leads to all sorts of unwanted side-effects and for me the problem comes because the advantages of this different set-up are being considered as normal behaviour and the disadvantages as a fault.

Bye

Ian

 

[Lovacott]

Part of the job of a (correctly aligned) derailleur cage is to supply the chain perfectly parallel to the sprockets, so it doesn't matter what angle the rest of the chain is.

I do have a very slight wobble right to left in the crankset but it's only about half a millimetre or so.

I replaced the BB cup and cones with a cartridge and fitted a new crankset, but the left to right travel remained. There must be a very slight frame alignment issue?

That said, it wouldn't alter the speed that the chain derails on the back.

 

[Lovacott]

If I read the posts correctly the OP is deliberately incorrectly setting up the indexing so that instead of the pulley/jockey wheels being directly below the selected sprocket they are offset towards the next larger sprocket.

You say incorrectly, but it's correct for me.

As I have said before, it's either quick down changes or quick up changes. The adjustment to switch between one and the other is tiny.

The rear mech is new but it's still only a £20 Tourney so maybe it doesn't have the best quality spring? The cables are new and run freely, the shifters are only six months old (Shimano Revoshift twist grip gears).

 

[MontyVeda]

I wouldn't put too much faith in the cost of your rear mech.

When i bought my MTB 20 years ago, it was second hand and needed a new rear mech. I was skint so spent £7.99 on a basic Shimano Acera one. I eventually got it perfectly indexed and a couple of years later, i upgraded the Acera rear mech to an XT one. It made no difference whatsoever... none, nowt, zilch. They even felt about the same weight with one in each hand when i was swapping them over. I've still got the Acera mech which will be going back on should i need to replace the XT one.

That's my personal experience.

 

[Lovacott]

I wouldn't put too much faith in the cost of your rear mech.

Materials quality would be the major difference. I used to work in steel fabrication and there is a world of difference between PT490 boiler plate and structural stuff like a 275 or 290.

The last big sheet of PT490 we bought cost us fair bit more than the same sized bit of structural steel would have cost.

To look at, you can't tell a bit of 490 from a bit of 275.

 

[MontyVeda]

I don't know much about boilers but I do know that my two rear mechs, one costing less than a tenner and another costing around four times more performed exactly the same.