On a 9-speed MTB triple chainset (or really any triple to work with Shimano front shifters and derailleurs) is the gap between middle and outer meant to be the same as between inner and middle?
My (11-speed) chain is able to get jammed between the inner and middle rings (9-speed chainset) but it cannot fit between the middle and outer. As well as that, I have got 2mm spacers on the inner chainring (long story I won't get into here).
If I can physically fit the chain between the inner and middle but it cannot fit in the gap between middle and outer, those 2mm spacers either need to be 1mm, or need to not be there at all, right?
I just wonder if the gap between the chainrings is meant to be equal, I assume so, but it's best to ask. If the chain can't fit between middle and outer but can fit between inner and middle and they should have equal gaps, I know my setup is wrong.
Thanks in advance.
Is the gap between middle and outer the same as between inner and middle?
Is the gap between middle and outer the same as between inner and middle?
We'll always be together, together on electric bikes.
Re: Is the gap between middle and outer the same as between inner and middle?
the centre to centre spacing is meant to be approximately constant, but
a) it often isn't, quite and
b) it isn't the only thing that determines whether the chain can get stuck or not and
c) if you have that problem it may not be one you can solve just by changing the chainrings, not on the inner to middle of a triple anyway.
cheers
a) it often isn't, quite and
b) it isn't the only thing that determines whether the chain can get stuck or not and
c) if you have that problem it may not be one you can solve just by changing the chainrings, not on the inner to middle of a triple anyway.
cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Re: Is the gap between middle and outer the same as between inner and middle?
I measured the 4 washers (a huh huh huh sorry "chainring bolt spacers"!) and they are all different thicknesses: 1.9mm, 1.9mm, 1.8mm, 1.6mm. 
Measuring myself, a 9-speed chain is 6.5mm whereas an 11-speed chain is 5.6mm. That's a difference of 0.9mm then /2 = 0.45mm so that's probably how much thinner my new spacers need to be: 1.5mm as opposed to 2mm that's on it now.
I tried with no spacers and the chain catches the middle/outer chainring bolts, so it definitely needs spacers on it, of some thickness.
I shall just experiment with 1.5mm thick and 1mm thick washers. It's a funny setup that needs spacers that would typically be the wrong thickness. Where there's least clearance on the chain is where there's bumpy parts of the middle chainring but it looks like it's at least a 1mm gap there.
Call them washers and they are about £1.50 for 4. Call them "chainring bolt spacers" and they are about £3.50 for 4. In reality they are just washers @ ID = 8mm / OD = 12mm. The 4 on my setup now are a mix of god knows what and all protrude beyond the bolt head.
Cheers Brucey.
Measuring myself, a 9-speed chain is 6.5mm whereas an 11-speed chain is 5.6mm. That's a difference of 0.9mm then /2 = 0.45mm so that's probably how much thinner my new spacers need to be: 1.5mm as opposed to 2mm that's on it now.
I tried with no spacers and the chain catches the middle/outer chainring bolts, so it definitely needs spacers on it, of some thickness.
I shall just experiment with 1.5mm thick and 1mm thick washers. It's a funny setup that needs spacers that would typically be the wrong thickness. Where there's least clearance on the chain is where there's bumpy parts of the middle chainring but it looks like it's at least a 1mm gap there.
Call them washers and they are about £1.50 for 4. Call them "chainring bolt spacers" and they are about £3.50 for 4. In reality they are just washers @ ID = 8mm / OD = 12mm. The 4 on my setup now are a mix of god knows what and all protrude beyond the bolt head.
Cheers Brucey.
We'll always be together, together on electric bikes.
Re: Is the gap between middle and outer the same as between inner and middle?
My Stronglight Z Light triple on Moulton was problematical from Day One in this regard.
The spacers between middle an outer were too wide and the chain often didn't go onto the middle ring and spun in between.
I took the spacers out and fitted them on a mandril and spun them with my drill against the side of a bench grinder to reduce them.
Trial and error over the weeks got them correct.
The spacers between middle an outer were too wide and the chain often didn't go onto the middle ring and spun in between.
I took the spacers out and fitted them on a mandril and spun them with my drill against the side of a bench grinder to reduce them.
Trial and error over the weeks got them correct.
Mick F. Cornwall
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Tigerbiten
- Posts: 2503
- Joined: 29 Jun 2009, 6:49am
Re: Is the gap between middle and outer the same as between inner and middle?
Manc33 wrote:I shall just experiment with 1.5mm thick and 1mm thick washers.
You can pick up thin (0.45mm, 1.2mm) chainring bolt spacers at Spa Cycles for £1.
Thicker spacers (2mm upwards) are £2.
But postage is around £4 if you don't spend enough for free postage.
Luck .......
Re: Is the gap between middle and outer the same as between inner and middle?
Mick F wrote:My Stronglight Z Light triple on Moulton was problematical from Day One in this regard.
The spacers between middle an outer were too wide and the chain often didn't go onto the middle ring and spun in between.
I took the spacers out and fitted them on a mandril and spun them with my drill against the side of a bench grinder to reduce them.
Trial and error over the weeks got them correct.
Yeah you can change gear 50 times and not have it happen... but on just the right or rather the wrong shift, it can slip between chainrings. The sprocket the chain is on at the cassette also seems to matter.
We'll always be together, together on electric bikes.
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Tigerbiten
- Posts: 2503
- Joined: 29 Jun 2009, 6:49am
Re: Is the gap between middle and outer the same as between inner and middle?
On my bent trike, the 55/38 double chainrings on my HSD are very sensitive to chainring spacer size.
My main troube is the chainline of the outer ring is fixed due to how the spider is fixed to the drive.
So with 2mm spacers, the chain just rubs on the outer ring.
And with 4mm spacers, the chain can occasionally drop between the rings.
That makes 3mm spacers the goldilocks size where everything is just right .......
Luck ....... D
My main troube is the chainline of the outer ring is fixed due to how the spider is fixed to the drive.
So with 2mm spacers, the chain just rubs on the outer ring.
And with 4mm spacers, the chain can occasionally drop between the rings.
That makes 3mm spacers the goldilocks size where everything is just right .......
Luck ....... D
Re: Is the gap between middle and outer the same as between inner and middle?
I'm not well enough to ride, but well enough to do some bike tinkering.
I'm in the process of cleaning the transmission on Moulton. I'll take off the chainset to clean it properly and check out the BB.
I'll measure my spacers that I ground down.
3mm sounds right.
Back later for accurate figure.
I'm in the process of cleaning the transmission on Moulton. I'll take off the chainset to clean it properly and check out the BB.
I'll measure my spacers that I ground down.
3mm sounds right.
Back later for accurate figure.
Mick F. Cornwall
Re: Is the gap between middle and outer the same as between inner and middle?
Memory slips a bit! 
My outer and middle fit on the crank webs, and the inner is fitted onto the middle. Five bolts each.
The webs on the crank between outer and middle is 3.3mm
The spacers between middle and inner are 3.3mm as well.
Can't remember what the original thickness of the spacers were, but I would expect they were 4mm.
With them reduced to the same thickness and the crank webs - 3.3mm - I've not had one problem.
My outer and middle fit on the crank webs, and the inner is fitted onto the middle. Five bolts each.
The webs on the crank between outer and middle is 3.3mm
The spacers between middle and inner are 3.3mm as well.
Can't remember what the original thickness of the spacers were, but I would expect they were 4mm.
With them reduced to the same thickness and the crank webs - 3.3mm - I've not had one problem.
Mick F. Cornwall
Re: Is the gap between middle and outer the same as between inner and middle?
I'm ending up going to increments of 0.5mm here.
2mm spacers worked with a 9s chain (it never slipped between the middle and inner in real-world usage) but on a 11s chain it can slip between them. This is only between middle and inner, a 9s or a 11s chain cannot fit between the middle and outer, so that's at least covered, but it means the inner probably is spaced too wide. Although a 9s chain never slipped between the middle and inner while using the bike, I can physically fit an offcut of 9s chain between there.
So it's probably going to have to be 1.5mm spacers, then I am pretty much accommodating for the 11s chain that's 0.9mm thinner (or 0.45mm per side thinner) although, if I can fit that offcut of 9s chain between the chainrings on 2mm spacers, it follows that a 11s chain - with a 0.45mm difference across half of it - can also slip between with spacers reduced to 1.5mm, because that equals it all out between 9s and 11s chains - the gap is almost the same, barring the 0.05mm between the 0.5mm difference of the spacers and the fact that half the width of the 11s chain, is 0.45mm thinner. Wait I'm not finished, nearly there...
So perhaps 2 sets of spacers might be the best bet - 1.5mm if using a 9s chain and 1mm if using a 11s chain (so long as on the 11s chain, the chain isn't catching on the chainring bolts of the middle+outer, which it won't/can't on a 9s with 1.5mm spacers so it should be alright).
... and breathe again
2mm spacers worked with a 9s chain (it never slipped between the middle and inner in real-world usage) but on a 11s chain it can slip between them. This is only between middle and inner, a 9s or a 11s chain cannot fit between the middle and outer, so that's at least covered, but it means the inner probably is spaced too wide. Although a 9s chain never slipped between the middle and inner while using the bike, I can physically fit an offcut of 9s chain between there.
So it's probably going to have to be 1.5mm spacers, then I am pretty much accommodating for the 11s chain that's 0.9mm thinner (or 0.45mm per side thinner) although, if I can fit that offcut of 9s chain between the chainrings on 2mm spacers, it follows that a 11s chain - with a 0.45mm difference across half of it - can also slip between with spacers reduced to 1.5mm, because that equals it all out between 9s and 11s chains - the gap is almost the same, barring the 0.05mm between the 0.5mm difference of the spacers and the fact that half the width of the 11s chain, is 0.45mm thinner. Wait I'm not finished, nearly there...
So perhaps 2 sets of spacers might be the best bet - 1.5mm if using a 9s chain and 1mm if using a 11s chain (so long as on the 11s chain, the chain isn't catching on the chainring bolts of the middle+outer, which it won't/can't on a 9s with 1.5mm spacers so it should be alright).
... and breathe again
We'll always be together, together on electric bikes.
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nigelnightmare
- Posts: 709
- Joined: 19 Sep 2016, 10:33pm
Re: Is the gap between middle and outer the same as between inner and middle?
Dear Manc33,
The answer to your original question is YES.
So if yours isn't, find out why and rectify...…
…..Job done!
P.S.
It is best to use 9 speed chains on 9speed running gear as that is what it was designed for.
Running 5/6/7/8/10/11/12 or 1/8" and you will have problems to say the least!...…
…...Basically not recommended.
The answer to your original question is YES.
So if yours isn't, find out why and rectify...…
…..Job done!
P.S.
It is best to use 9 speed chains on 9speed running gear as that is what it was designed for.
Running 5/6/7/8/10/11/12 or 1/8" and you will have problems to say the least!...…
…...Basically not recommended.
Re: Is the gap between middle and outer the same as between inner and middle?
With mine, it was a 10sp triple with a 10sp chain.
The chain often sat half-way between the inner and the middle.
Reducing the spacers from 4mm to 3.3mm solved the design problem.
Yes, it was a design problem.
The crank web is 3.3mm between outer and middle and was correct. The spacers between middle and inner were too wide.
Trim them down ..........
Job done!
The chain often sat half-way between the inner and the middle.
Reducing the spacers from 4mm to 3.3mm solved the design problem.
Yes, it was a design problem.
The crank web is 3.3mm between outer and middle and was correct. The spacers between middle and inner were too wide.
Trim them down ..........
Job done!
Mick F. Cornwall