I saw something like this the other year. After spending some time comparing it with a near-identical setup on another bike, I realised that on the problem bike, a pin protruding from the inside face of the outer chainring was missing. (It wasn't entirely clear how it had disappeared - possibly wear or impact, though worryingly there was some evidence that it was a misguided "fix" by a mechanic at the bike shop.) Without that pin the chain simply wouldn't lift onto the outer ring.
This was on original Shimano chainrings, not Stronglight, but it may be worth considering.
Front mech not shifting to large ring
Re: Front mech not shifting to large ring
Once again, thanks everyone. Some thinks to try out when I return home on Tuesday.
Re: Front mech not shifting to large ring
https://janheine.wordpress.com/2018/08/20/rene-herse-11-speed-chainrings-in-new-sizes/
explains a bit more about what is involved in getting chainring designs so that they work reliably with 10, 11s transmissions.
Not 'simple' any more.
cheers
explains a bit more about what is involved in getting chainring designs so that they work reliably with 10, 11s transmissions.
Not 'simple' any more.
cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Re: Front mech not shifting to large ring
I use 6703 front changers - newish ones, mind - with both Ultegra and Dura Ace triple chainsets (both 52-39-30). They work perfectly with the matching (10 speed) 5703 STI lever. I also use a 5703 triple front mech with a Spa triple chainset of 26-36-46. This won't work very well with an STI changer but will work with an unidexed bar-end lever.
The Spa triple rings have ramps and pins and these do lift the chain, but only with an optimum throw of the changer, which occurs with the unindexed bar-end lever but not a triple STI lever. I presume the STI-pulled throw of the mech is not matched well enough to the spacing of the Spa chainset rings, which is advertised as suitable for 9-11 speed systems, as I recall.
In addition, although I can effect good changes with the bar-end lever, which changes work smoothly without chatter or hesitation, I do have to be careful not the go middle to big ring if the chain is on the smallest (highest gear) sprockets (the RH 2 or 3) as the chain will sometimes unship on to the crank and it's anti-jamming pin. This despite very careful positioning and limiting of the 5703 front derailleur mech. I believe this happens because the mech is meant for a 52 ring, not a 46 ring; and perhaps also a ring & teeth that are of a very critical thickness.
Brucey is right to say that modern front mechs are pernickety about the rings they prefer. Shimano triples are the most pernickety. Their shape is complex and meant to push the chain in a way that exactly matches the intended rings of the Shimano chain set/rings for which they're designed.
Cugel
The Spa triple rings have ramps and pins and these do lift the chain, but only with an optimum throw of the changer, which occurs with the unindexed bar-end lever but not a triple STI lever. I presume the STI-pulled throw of the mech is not matched well enough to the spacing of the Spa chainset rings, which is advertised as suitable for 9-11 speed systems, as I recall.
In addition, although I can effect good changes with the bar-end lever, which changes work smoothly without chatter or hesitation, I do have to be careful not the go middle to big ring if the chain is on the smallest (highest gear) sprockets (the RH 2 or 3) as the chain will sometimes unship on to the crank and it's anti-jamming pin. This despite very careful positioning and limiting of the 5703 front derailleur mech. I believe this happens because the mech is meant for a 52 ring, not a 46 ring; and perhaps also a ring & teeth that are of a very critical thickness.
Brucey is right to say that modern front mechs are pernickety about the rings they prefer. Shimano triples are the most pernickety. Their shape is complex and meant to push the chain in a way that exactly matches the intended rings of the Shimano chain set/rings for which they're designed.
Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
John Maynard Keynes
John Maynard Keynes
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PDQ Mobile
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Re: Front mech not shifting to large ring
It's primitive!
Dragging a chain sideways off a toothed wheel, just primitive.
Compared to sophisticated IHG or other stuff.
But primitive should also be simple, that's part of it's reliable rugged nature.
And that's its big plus.
If it ain't broke don't fiddle with the design!
Who needs more than 9 on a cassette anyway?
Not me.
My old stuff works great. Mechs have loads of pivot wear/play too.
Never unships to the crank when properly adjusted.
Dragging a chain sideways off a toothed wheel, just primitive.
Compared to sophisticated IHG or other stuff.
But primitive should also be simple, that's part of it's reliable rugged nature.
And that's its big plus.
If it ain't broke don't fiddle with the design!
Who needs more than 9 on a cassette anyway?
Not me.
My old stuff works great. Mechs have loads of pivot wear/play too.
Never unships to the crank when properly adjusted.
Re: Front mech not shifting to large ring
PDQ Mobile wrote:It's primitive!
Dragging a chain sideways off a toothed wheel, just primitive.
Ever looked inside a car gearbox?
Primitive action, sophisticated solution.
The older I get the more I’m inclined to act my shoe size, not my age.
Re: Front mech not shifting to large ring
As I understand the thread, this is original Ultegra mechanism, shifting Stronglight rings.
Do the Stronglight rings have the same ramps, odd pins, and reduced height teeth that Shimano fit to their rings ? If not, don't expect it to work as well, and that it fails to work isn't totally surprising.
The old world, no-ramps rings worked when people used friction shift downtube, or bar-end shifters. Could overshift slightly and back-off as the chain engaged, plus fatter chains in the old 5/6 speed world. Newer indexed shift mechanisms need those ramps and other twiddly bits on the rings.
- Nigel
Do the Stronglight rings have the same ramps, odd pins, and reduced height teeth that Shimano fit to their rings ? If not, don't expect it to work as well, and that it fails to work isn't totally surprising.
The old world, no-ramps rings worked when people used friction shift downtube, or bar-end shifters. Could overshift slightly and back-off as the chain engaged, plus fatter chains in the old 5/6 speed world. Newer indexed shift mechanisms need those ramps and other twiddly bits on the rings.
- Nigel
Re: Front mech not shifting to large ring
Nigel wrote:As I understand the thread, this is original Ultegra mechanism, shifting Stronglight rings.
Do the Stronglight rings have the same ramps, odd pins, and reduced height teeth that Shimano fit to their rings ? If not, don't expect it to work as well, and that it fails to work isn't totally surprising.
- Nigel
The thing is I've successfully been using this exact setup with Stronglight chainrings since the first Ultegra rings wore out in 2010. It has only become an issue in recent months, and a while after any of the components were replaced.
Will do some more investigating tomorrow.
As it stands I'm tempted to buy some new 5703 shifters, a 5703 front mech and matching chainrings - the only problem is the outer is only available up to 50t (also the limit for the front mech apparently), which seems ridiculously small for a road chainset!
Re: Front mech not shifting to large ring
toontra wrote:......
As it stands I'm tempted to buy some new 5703 shifters, a 5703 front mech and matching chainrings - the only problem is the outer is only available up to 50t (also the limit for the front mech apparently), which seems ridiculously small for a road chainset!
50 toof big ring not just "small" but "ridiculously small"!? Wot, even with your 9 toof sprocket?But perhaps you are Cav in disguise.
The 5703 mech will work with a 52 ring, should you fit, say an Ultegra 6703 ring. Whilst the Shimano chain ring pin/ramp/spacing aspects are pernickety, the other Shimano directives to match like with like groupset-wise ain't necessarily so.
* Rear mechs have the ability to handle a bigger sprocket than Shimano says.
* A 10 speed chainset works fine with an 11 speed chain.
* Stronglight rings work with some Shimano front mechs and STI lever (but you knew that).
Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
John Maynard Keynes
John Maynard Keynes
Re: Front mech not shifting to large ring
I would look carefully at
- the new chain; is it the same as the old one?
- the state of the chainrings (are there any burrs on the teeth?)
- whether the middle ring has been refitted in the wrong timing vs the big ring
- whether the FD is now permanently deformed so that it cannot work now.... pictures?...
Chains vary in shift quality hugely. If you have (on a whim) changed chain brands then I would suggest that the simplest thing would be to try another example of the original chain type. If you have stuck with the same chain type throughout it might have worked Ok when the chainrings were new but now they are not and the type of chain can make more difference.
FWIW one of my chums reported 'skating on the big ring' with a new chain (which usually presages the situation you are in) and the chainrings that didn't look badly worn to me. A 10s system.... We did two things;
1) bought new chainrings (of the correct type) and
2) changed to a different brand of chain
The shifts were tolerable with the new chainrings and a new (OEM, matched chain, so a 'one-brand transmission' ) but the polish marks on the sprocket sides and my Vernier calipers said the chain was out of spec; too wide for a 10s chain by 0.1mm. So we changed to a different brand of chain and the shifting became much better than it had ever been at both front and rear.
So my advice is always to try a different chain or two. Worst case outcome is that you end up with a spare chain or two you didn't need just yet. Best case is that you spare yourself from having to buy a whole new transmission.....
cheers
- the new chain; is it the same as the old one?
- the state of the chainrings (are there any burrs on the teeth?)
- whether the middle ring has been refitted in the wrong timing vs the big ring
- whether the FD is now permanently deformed so that it cannot work now.... pictures?...
Chains vary in shift quality hugely. If you have (on a whim) changed chain brands then I would suggest that the simplest thing would be to try another example of the original chain type. If you have stuck with the same chain type throughout it might have worked Ok when the chainrings were new but now they are not and the type of chain can make more difference.
FWIW one of my chums reported 'skating on the big ring' with a new chain (which usually presages the situation you are in) and the chainrings that didn't look badly worn to me. A 10s system.... We did two things;
1) bought new chainrings (of the correct type) and
2) changed to a different brand of chain
The shifts were tolerable with the new chainrings and a new (OEM, matched chain, so a 'one-brand transmission' ) but the polish marks on the sprocket sides and my Vernier calipers said the chain was out of spec; too wide for a 10s chain by 0.1mm. So we changed to a different brand of chain and the shifting became much better than it had ever been at both front and rear.
So my advice is always to try a different chain or two. Worst case outcome is that you end up with a spare chain or two you didn't need just yet. Best case is that you spare yourself from having to buy a whole new transmission.....
cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Re: Front mech not shifting to large ring
Good advice, Brucey. Will have a thorough inspection tomorrow or Thursday.
Re: Front mech not shifting to large ring
Is the new chain different to the old chain? Do some chains have a right way and wrong way around? Have you got the old chain lying around to check the new chain against?
Re: Front mech not shifting to large ring
Well - 2 hours spent fiddling. Mech & crankset came off. Everything thoroughly cleaned, chainrings off and reassembled, mech re-aligned and adjusted from scratch (cable tension, lo/hi screws) and chain refitted.
It appears to have worked - on the workstand at least (weather too nasty to road-test). Not sure what individual thing helped but I suspect the height of the mech clamp was the main issue - the gap was larger than the recommended 1-2mm - more like 3-4. Not sure how this happened as the clamp has never never been touched and chainring replacement has always been of the same tooth count.
Anyway, hopefully that has sorted it and I've got all my gears back. Fiddly things, front mechs!!
Thanks for all the helpful suggestions.
It appears to have worked - on the workstand at least (weather too nasty to road-test). Not sure what individual thing helped but I suspect the height of the mech clamp was the main issue - the gap was larger than the recommended 1-2mm - more like 3-4. Not sure how this happened as the clamp has never never been touched and chainring replacement has always been of the same tooth count.
Anyway, hopefully that has sorted it and I've got all my gears back. Fiddly things, front mechs!!
Thanks for all the helpful suggestions.
Re: Front mech not shifting to large ring
toontra wrote:Well - 2 hours spent fiddling. Mech & crankset came off. Everything thoroughly cleaned, chainrings off and reassembled, mech re-aligned and adjusted from scratch (cable tension, lo/hi screws) and chain refitted.
It appears to have worked - on the workstand at least (weather too nasty to road-test). Not sure what individual thing helped but I suspect the height of the mech clamp was the main issue - the gap was larger than the recommended 1-2mm - more like 3-4. Not sure how this happened as the clamp has never never been touched and chainring replacement has always been of the same tooth count.
Anyway, hopefully that has sorted it and I've got all my gears back. Fiddly things, front mechs!!
Thanks for all the helpful suggestions.
Don't want to be negative but I'd take it out on the road before celebrating/doing extra work on top of this.
(see my thread on not getting onto the small ring!).
Someone with more knowledge than me will be able to say why there is all too often this discrepancy between workstand and road - bike frame flex?
Sweep