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PostPosted: Tue Apr 30, 2013 6:24 pm 
retrobike rider
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I have some RSR cranks with no chainrings. Purchased a set of Middleburn rings. New rings turn up and I can see a possible problem. Middleburn outers have a pin which is supposed to be positioned behind the crank arm. The middle ring also has a small detail in the bore which is again supposed to be aligned with the arm. However, The spider on the Cooks has one leg behind the arm so you are forced to put the chainring alignment either before or after the crank arm. Which do you think is best? Does it really matter? Does anyone give a toss? Is it all irrelavent as I will never be able to tighten the bolt behind the arm and it will fall out causing Armageddon?


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PostPosted: Tue Apr 30, 2013 6:56 pm 
retrobike rider
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the last bit, but the only thing is your shifting ramp will not be in quit the best place. work out which way works best for the ramping.. if you have any that is. of course that might be a complete 180 turn.

I do not know.


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PostPosted: Tue Apr 30, 2013 7:21 pm 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
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Location: New Forest, UK
Do a 180 degree turn. IIRC the anti-jam pin is threaded, failing that drill it out from the back. If you drill and tap a small hole in the right place, a small M4 bolt will stop jamming.


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PostPosted: Tue Apr 30, 2013 7:40 pm 
Gold Trader
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FluffyChicken wrote:
but the only thing is your shifting ramp will not be in quit the best place.


Yes it will, as all 3 rings will be similarly displaced. Although I don't recall Middleburn rings having ramps?


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PostPosted: Tue Apr 30, 2013 8:41 pm 
retrobike rider
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My_Teenage_Self wrote:
FluffyChicken wrote:
but the only thing is your shifting ramp will not be in quit the best place.


Yes it will, as all 3 rings will be similarly displaced. Although I don't recall Middleburn rings having ramps?


Ah, I seem to have deleted the part that I was meaning with respect to shifting under/not under power (I had typed it, but must have deleted during editing, don't you love small mobile phones). They are normally designed to shift in the places the load is lowest, or at least Shiamno/Suntour used to be.
No idea if Middleburn SlickShift is, not looked at their profile on mine.

The 180 turn only 'fully' if the ramps/pins/cuts stay in the same place.

I've never had to worry about it :lol:, though some people made some for this hidden arm setup (Sugino and anyone that rebranded them e.g. Tioga and also TA I think?)


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PostPosted: Tue Apr 30, 2013 9:05 pm 
retrobike rider
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Thanks for all the info. These are the slickshift version, so they have some shaping and pins to aid shifting. It is going to be about 50 degrees out from where they intended, so I doubt if I will notice the difference. I will probably just remove the pin sticking out. That hidden chain ring bolt is a bit of a PITA though. I am going to have to make up a tubey key thingy. The inner ring screws look pretty scabby, turned up some new spacers and was going to replace the screws. If anyone needs some nice new Middleburn inner ring screws I have a packet. Didn't click that the Cooks ones are longer.... :facepalm:


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