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Slabby chain conversion for phatter wheels


Havoc

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Posted

I used to run 180/55 180/60 and 190/60 Inters on 5.5 inch rims on a 750 slabby with only a slight bend in the torque arm.  Always had 530 chain.   Gearbox output shafts are different lengths between differnet engines/boxes.  Mine all happened to be "long" shafts with long spacers for the gearbox sprocket.  Not sure if you would have issues with a short collar ahaft.

 

Posted

im trying out an reversed zx636 520 front sprocket. it gives me an extra 9mm clearence. and ill need to take off 2mm on the rear hub from the triumph wheel

Posted

Where is the extra clearance needed? A slimmer chain will only give a little more clearance between the outside edge of the chain and the frame. To get the chain line correct for a slabby engined bike with a 6" race wheel meant moving the chain inboard as much as it would go whilst still clearing the tyre or it would foul the frame. Simply changing chain sizes would not have done this.

Posted
1 hour ago, Dezza said:

Where is the extra clearance needed? A slimmer chain will only give a little more clearance between the outside edge of the chain and the frame. To get the chain line correct for a slabby engined bike with a 6" race wheel meant moving the chain inboard as much as it would go whilst still clearing the tyre or it would foul the frame. Simply changing chain sizes would not have done this.

It does make a difference. On my 750m and my 750 slabbie a 520 chain just clears using a 180/60 tyre, with a 530 on the 750m it wore away a little of the tyres shoulder.

Posted

The 520 chain must have had thinner side plate, o-rings or both. If the inner face of the sprocket remains unaltered, and the overall width of the side plates+oring is the same for the 520 and 530 chains in question, the space between the inner edge of the chain and tyre must be the same.

Posted
2 hours ago, Dezza said:

The 520 chain must have had thinner side plate, o-rings or both. If the inner face of the sprocket remains unaltered, and the overall width of the side plates+oring is the same for the 520 and 530 chains in question, the space between the inner edge of the chain and tyre must be the same.

Good point.

Posted (edited)

520 - 525 chains have a smaller diameter pin and smaller pin width 

plate thicknesses vary  but not by much (0.5mm at the most if you get a high performance chain).

Thinner sprocket thinner chain usually gives about 1-2mm additional clearance to the tyre not so much the hub and clearance to the frame.

A 4.5 in wheel has 102mm from CL to back of the sprocket

A 5.5in wheel has 108mm Cl to sprocket inner face so assuming the wheel is on the center line of the bike you have just lost @ 6mm clearance to the frame

 

Edited by Lachie04

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