Spa XD2 chainset - which way round chainrings?

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Sweep
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Spa XD2 chainset - which way round chainrings?

Postby Sweep » 7 Aug 2019, 9:25am

Sorry patient folks, me again.

Kinda related to my recent post on the XD2.

Some folks on here have this chainset I think and so if theirs is still fitted with the original rings they could maybe be kind enough to check theirs.

But replies from other folk more than welcome of course.

After well laid plans to keep everything in order for reassembly (I have changed Shimano chain rings before) my problems with the bolt behind the crank arm may possibly have caused me to put things back in the wrong way.

I ask because the bike has re-encountered a problem I had before with changing to the bottom ring, so before dealing with that and other variables I would like to rule out any chainring issues.

So to the issue. It's to do with a sort of "shelf/circular ridge/chamfer that all of the rings have.

I have clearly put the big ring back on the right way round as the peg is positioned where it should be behind the crank arm.

This ring has the "shelf" facing the frame.

The middle and small rings have a notch at one point on the rings and from checking before I took the thing apart this is clearly meant to go opposite the drive side crank arm. So I have done this with both on reassambly.

The "shelf" on the middle ring is facing away from the frame. Different from the big ring but I assume this must be correct as it puts what I take to be the pins for aiding shifting on the side of the ring facing the frame?

The little ring. The "shelf" for this is facing the frame. I have a memory (quite possibly faulty) that when I looked at the chainset before disassembly this surface was flat.

Also, as another check (and will I assume be relevant to all other chainring tinkering whatever the brand) if there is a recess on the fixing holes is this to accept the allen bolt or the nut?

Thanks in anticipation.

If I can clear up this I am pretty confident that I can solve the other issue with some more tinkering for I sorted it before.
Sweep

Brucey
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Re: Spa XD2 chainset - which way round chainrings?

Postby Brucey » 7 Aug 2019, 10:02am

if refitting used rings the wear marks on the teeth are a very good guide to which way round they were fitted.


If fitting new rings, compare them with the used ones.

cheers
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Sweep
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Re: Spa XD2 chainset - which way round chainrings?

Postby Sweep » 7 Aug 2019, 10:08am

Brucey wrote:if refitting used rings the wear marks on the teeth are a very good guide to which way round they were fitted.


If fitting new rings, compare them with the used ones.

cheers

Thanks for the reply brucey but am a very bad judge of things like wear so I need to get this right before using the existing chainset and rings as a template for any new ones I may fit. I may by the by be fitting a new middle in the near future (a stronglight) I have sitting around.

If all else fails I could I suppose email Spa, though I appreciate that they are very busy/this won't be their greatest email priority.

In the meantime I am using a different bike as I don't want to screw anything up.
Sweep

pwa
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Re: Spa XD2 chainset - which way round chainrings?

Postby pwa » 7 Aug 2019, 10:11am

The recess must be for the allen head bolts. And I think I am right in saying that chain rings have any writing / etched numbers etc facing outward, i.e. facing the pedal arm. It sounds to me like the middle ring is the one you have most concern about because if the shift that is reluctant is from middle to smallest, the smallest ring is not having any say in that. The middle ring is hanging on when it should let go.

Bmblbzzz
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Re: Spa XD2 chainset - which way round chainrings?

Postby Bmblbzzz » 7 Aug 2019, 10:12am

The pins are visible on both sides of the middle ring but are far more pronounced on the inside, ie. facing the frame.

Brucey
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Re: Spa XD2 chainset - which way round chainrings?

Postby Brucey » 7 Aug 2019, 10:13am

Image

you can see the wear here, right?

Even if it is not obvious from the side view, the loaded faces of the teeth will be polished/worn on used chainrings.

BTW you can also see the marks on this (inner/middle) ring from where the spider has borne against it.

cheers
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slowster
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Re: Spa XD2 chainset - which way round chainrings?

Postby slowster » 7 Aug 2019, 10:27am

I have an XD2 triple fitted with TA chainrings and a TD2 triple fitted with Spa chainrings, but I am not quite sure what you mean by some of your comments. Unless I have misunderstood, the chamfer goes on the inside face because the gaps in the chamfer are the ramps which improve the changes from inner to middle and middle to big rings.

Sweep wrote:The middle and small rings have a notch at one point on the rings and from checking before I took the thing apart this is clearly meant to go opposite the drive side crank arm. So I have done this with both on reassambly.

The chainrings could be used on a TD type chainset (with 5 exposed bolts) or an XD (with one bolt concealed behind the crank). I haven't had time to look closely enough at my chainrings to compare, but I would have though that the location of any notch or similar in a chairing would influence/indicate its position with regard to the other rings, not its position with respect to the chainset*, and is there to ensure the ramps and pins are correctly aligned.

(* at least not directly although the pin on the outer which stops the chain falling into the gap between ring and chank will dictate the position of the outer ring, and position of the middle and inner rings would then be determined by their relationship to the outer ring).

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Sweep
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Re: Spa XD2 chainset - which way round chainrings?

Postby Sweep » 7 Aug 2019, 10:32am

Bmblbzzz wrote:The pins are visible on both sides of the middle ring but are far more pronounced on the inside, ie. facing the frame.


Yes that's the way I have it at the moment - I did see the smaller "pins" on the other side but wasn't sure if they were shifting pins as such or just bits of metal holding the pin on the other side on. I think the smaller ones facing away from the frame are also recessed, which to me suggested that they weren't shifting guides.

It's the small ring I am most concerned about but maybe it is irrelevant which way round it goes. Or maybe it IS relevant once it is worn?

As for the other question, it is possible that wear/damage of some sort on the middle ring is causing issues with the chain being released. On the other hand it all shifted well before I took things apart.

I took it apart as I had the feeling that there was some wear in the drivetrain causing drive efficiency issues, though not issues with changing.

(I have by the by also changed the cassette and tinkered with the front mech).

So it seems as if the outer and middle (from your input bmb) are the right way round - just the inner to wonder about.
Sweep

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Sweep
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Re: Spa XD2 chainset - which way round chainrings?

Postby Sweep » 7 Aug 2019, 10:37am

slowster wrote: I haven't had time to look closely enough at my chainrings to compare, but I would have though that the location of any notch or similar in a chairing would influence/indicate its position with regard to the other rings, not its position with respect to the chainset*, and is there to ensure the ramps and pins are correctly aligned..


The same thing surely slowster? By "notch" I mean a small bit of metal sticking up into the centre of the ring not a cut as such. I am sure that I have these positioned correctly. In any case it is the "faceplate" aspect of the rings I am concerned about, ie which facing the frame/away from the frame. The notch, or more accurately bump, is to do with the rotational positioning.
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pwa
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Re: Spa XD2 chainset - which way round chainrings?

Postby pwa » 7 Aug 2019, 10:38am

Inner rings tend to be very plain affairs. If there is a slight recess for the bolt I would go with that.
But if the chain won't go from middle to smallest, the smallest ring isn't even getting a sniff of the chain so its exact positioning isn't responsible.
Last edited by pwa on 7 Aug 2019, 10:43am, edited 1 time in total.

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Sweep
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Re: Spa XD2 chainset - which way round chainrings?

Postby Sweep » 7 Aug 2019, 10:42am

slowster wrote:but I am not quite sure what you mean by some of your comments. Unless I have misunderstood, the chamfer goes on the inside face because the gaps in the chamfer are the ramps which improve the changes from inner to middle and middle to big rings..


I think you are referring to the rather "bulbous" looking things which yes I assume are to do with shifting. And yes these are facing inwards on the middle ring.

What I am referring to by "shelf" is a circular line on all of the three rings - as if you had cut the ring on a machine tool while turning it. It is there on all three rings but currently positioned differently. On the small ring it is currently facing the frame.
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pwa
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Re: Spa XD2 chainset - which way round chainrings?

Postby pwa » 7 Aug 2019, 10:45am

Sweep wrote:
slowster wrote:but I am not quite sure what you mean by some of your comments. Unless I have misunderstood, the chamfer goes on the inside face because the gaps in the chamfer are the ramps which improve the changes from inner to middle and middle to big rings..


I think you are referring to the rather "bulbous" looking things which yes I assume are to do with shifting. And yes these are facing inwards on the middle ring.

What I am referring to by "shelf" is a circular line on all of the three rings - as if you had cut the ring on a machine tool while turning it. It is there on all three rings but currently positioned differently. On the small ring it is currently facing the frame.

Is this shelf at the base of the teeth?

pwa
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Re: Spa XD2 chainset - which way round chainrings?

Postby pwa » 7 Aug 2019, 10:55am

After a quick look at some TA rings on a bike in my garage, there is a ramp / shelf presumably to aid shifting that is facing the frame on all three rings. It must be to allow the chain to ride up from a smaller to a larger ring. Getting the middle ring the wrong way round might, presumably, put the teeth further left than they ought to be. That would be enough to stop the chain dropping to the smaller ring. If the feature you describe is a ramp, it should face a smaller ring.
Last edited by pwa on 7 Aug 2019, 11:00am, edited 1 time in total.

slowster
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Re: Spa XD2 chainset - which way round chainrings?

Postby slowster » 7 Aug 2019, 10:59am

Right, I've just put my bike with the TD2 triple and Spa rings on the stand and had a closer look. There is a small 1mm-2mm deep notch on the inner and middle rings. These are positioned such that both notches are obscured by the crank arm (it would make sense on your XD2 with its concealed bolt that they were 180 degrees from the crank arm). There is no notch on the outer ring that I can see. The TA rings on my other bike have no such notches.

My chainset has the rings just as they were provided, already installed by Spa, i.e. I've not dismantled it yet. The lettering and tooth sizes are all on the outside face.
Last edited by slowster on 7 Aug 2019, 11:00am, edited 1 time in total.

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Sweep
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Re: Spa XD2 chainset - which way round chainrings?

Postby Sweep » 7 Aug 2019, 10:59am

pwa wrote:Is this shelf at the base of the teeth?

Yes it is - a sort of circular cut ridge (never known what to call it - apologies) and it seems to be a very simple way of telling folks which way round the rings go - once I have the "key" :)
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