Indexing Your Gears Is a Compromise Rather Than An Absolute.

[Blue Hills]

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.

mm - not maybe the most scientific test monty - I'm all for questioning companies' efforts to sell you up, and if anyone tries to convince me to buy something at a premium for its weight savings I'll maybe laugh in their face, but I rate a lot of the XT stuff.
So the Acera was on the bike for two years and the XT continues to perform after 18?
I have an old Ultegra rear mech that came on a bike I bought in 2004 and is still running on a second bike, despite once getting a bash that meant I had to have the sacrificial hanger bent back. It's of the tough solid metal type though, not the newer stuff, some of which looks like high-tech tinplate to me. It did get new jockey wheels a couple of years ago, but wouldn't be overly surprised to find that, barring bashes, it outlives me.
I also have a fair few second had XT front mechs - well worth it I think.

 

[Lovacott]

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.

I spent four years in Perth Australia writing weld procedures which would satisfy the local big players.

I wrote a WPS for Chevron in 2011 which they rejected for not specifying weld wire rated for -30c.

I don't know if any of you have ever set foot inside Western Australia, but it's a hot and harsh environment to say the very least.

Minus 30c is the range we had to design to, but it was a pointless target.

 

[Ajax Bay]

@Lovacott said (my comments in italics):
"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."
Not if you set up your gears properly.
"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."
When you're on a 2 chevron climb you will already be in your lowest gear. No gear changes will be required. If there are you need to review your gear selection technique and forward thinking, before the hill gets steep.
"To get quick changes down, you need a slightly slacker rear mech cable which in turn will make your changes up a bit hesitant."
The cable is only close to slack when you're in the smallest sprocket. At all other times the cable has tension. The effect you describe is a figment of your imagination. (See my suggestion at the bottom.)
"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."
Chains are marvellous things and are entirely content to operate at a slight angle. For a triple and 7 speed a chain works fine cross chaining and rear sprocket shifts are unaffected. Bear in mind that a 7 speed freewheel or cassette is narrower than higher speed drivetrains so the cross-chaining angle is less. It's physically possible to get a 3 x 7 to work perfectly in every gear (as has been reiterated upthread ^^^).
"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."
Not logical and not the case. I have discussed cable tension above.
"My rear mech is perfectly aligned and my indexing is very good. It's actually better than new."
How can a rear mech be better indexed than "new"?

I suspect the OP's issue (apart from the 'not crediting others with knowledge' issue) is that the shifters he's using (Shimano Revoshift) are twist-grip ones and the spring/ratchet in those doesn't offer the same quality of shift as triggers.

 

[roubaixtuesday]

I suspect the OP's issue (apart from the 'not crediting others with knowledge' issue) is that the shifters he's using (Shimano Revoshift) are twist-grip ones and the spring/ratchet in those doesn't offer the same quality of shift as triggers.

I've had bikes with trigger shifters, bar ends, down tube shifters, brifters and a singlespeed.

All work very satisfactorily, save for twist grip shifters, which are the very work of Beelzebub.

 

[Mr Celine]

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

Both my bikes are triples, the winter / commuter is 3x9 and the summer bike is 3x10. I'm off out soon over some hills and dales on the latter for some sunny perfection.

(I will admit triples can be fiddly to set up, but more so on the front mech IME.)

 

[Blue Hills]

yep triples can be tricky on first setting up - just got one working on a newbuild after some serious faffing.
But the rewards are great once done
As with so much else, things are far simpler with flat bars and some real bodging/using stuff out of its apparent spec can work well enough.
You can even get front rapidfires with 1 or 2 extra clicks to rapidly sort any irritating on-ride rattles - I don't see them as a significant compromise on the convenience of indexing rapidfires. I'm not sure they are still made but pretty easily available as good quality second hand items.

 

[MontyVeda]

mm - not maybe the most scientific test monty -

real world tests never are

 

[sleuthey]

Surely this all depends on how much you spend on your drive train. Eg if you have Tourney or SIS stamped on your rear mech then your chain, cassette and shifter are likely to be of a similar entry level quality. I agree on that case that there will be compromises. If you have Deore then good upon fettling. If you have XTR then perfect. If that were not the case then what is the point in buying expensive drive trains over entry level ones? Ok durability, shifting speed but to me that’s not important.

 

[Arrowfoot]

Twist grips should be banned.

 

[Lovacott]

Surely this all depends on how much you spend on your drive train. Eg if you have Tourney or SIS stamped on your rear mech then your chain, cassette and shifter are likely to be of a similar entry level quality. I agree on that case that there will be compromises. If you have Deore then good upon fettling. If you have XTR then perfect. If that were not the case then what is the point in buying expensive drive trains over entry level ones? Ok durability, shifting speed but to me that’s not important.

If there really was such a thing as the perfect drivetrain, it would be the standard on all bikes and I wouldn't have started this thread.

On the subject of cost, that's yet another compromise. The drivetrain on my new road bike is twice as good as my MTB Tourney setup, but the replacement costs are more than triple.

 

[Ming the Merciless]

Fact is,

Mine shifts swiftly up and down.

 

[sleuthey]

If there really was such a thing as the perfect drivetrain, it would be the standard on all bikes

That would mean that customers who don’t need perfection (just need to get from a to b) would have to pay extra for something they didn’t need.

 

[C R]

I think @Ajax Bay pointed to the problem being the grip shifters, which are nowhere near accurate enough on where they pull or release the cable. I have a tourney derrailleur that indexed perfectly on a six speed with a thumb trigger shifter, and performs equally well on an eight speed with a rapidfire sti.

 

[boydj]

I have old Shimano 105 triple 10 speed on the winter bike and re-cabled it at the tail end of last summer. The rear shifting was no problem, the front took a bit of trial end error to get it right. It has shifted pretty much perfectly since then, including big/big and small/small (when it's on the stand).

I did once service a relative's cheap mountain bike which had cheap Shimano triple setup with twist grip shifters - definitely the work of the devil - but they do work eventually, but nothing like the crisp shifting of a good road setup. There's no comparison with good quality road bike shifters. I prefer Campag to Shimano for the way it works, but both work perfectly well.

 

[T4tomo]

As soon as the OP mentioned Revoshift, you know what the issue is. I've been out today on 3x5 friction shifters, never missed a beat.

Revoshift is the work of the devil, shoot cheap and useless.