Member Contributer CHUCK2 Posted July 11, 2011 Member Contributer Share Posted July 11, 2011 Does rear suspension travel have any effect on the amount of chain slack? I'm asking about my VFR of course, but I wonder the same about my XR? Or any other bike for that matter. I know some of you will understand the geometry involved to be able to provide an answer. Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted July 11, 2011 Share Posted July 11, 2011 Oh yes it does. When the rear swingarm is at 0' angle, relative to the swingarm pivot, the chain will be at it's tightest. (think flat/level swingarm) Above or below that, it gets progressively looser. Since my rear ride height is maxed out, I have to run more chain slack at rest, or else it will be too tight underway and laden, and perhaps when hitting a bump. The only time it does not is when the centerline of the countershaft sprocket and the centerline of the swingarm pivot are the same. IIRC, there were a couple of bikes that utilized this setup over the years, but it makes the bike wide at the drive end. EDIT: BIMOTA did this, that's where I remembered it from. Keeps chain tension perfect throughout suspension stroke. See here: Link to comment Share on other sites More sharing options...
DDO-VFR Posted July 11, 2011 Share Posted July 11, 2011 Put another way.... Because the center point of the front sprocket is not concentric with the pivot point of the swing arm, the distance between the two sprockets will vary as the swing arm moves through its arc (due to suspension travel). The distance between the two sprockets (F to R) is NOT longest when the bike is sitting at rest. For this reason the chain must have enough slack to accommodate the maximum distance reached during compression of suspension (ie. the bike ass end is low). There is no other magic to 'chain slack'. 1" slack at rest will achieve the desired 'room for elogation' needed between the F-R sprockets during suspension compression. You're better a bit too loose than too tight. Hope it helps, Brian Link to comment Share on other sites More sharing options...
The Phantom Posted July 11, 2011 Share Posted July 11, 2011 IIRC, there were a couple of bikes that utilized this setup over the years, but it makes the bike wide at the drive end.EDIT: BIMOTA did this, that's where I remembered it from. Keeps chain tension perfect throughout suspension stroke. Wow, wide at the drive end alright! Looks more like my mother in law than a Bimota... BMW's X450 has the drive sprocket in the same plane as the pivot too: Link to comment Share on other sites More sharing options...
Member Contributer CHUCK2 Posted July 11, 2011 Author Member Contributer Share Posted July 11, 2011 Thanks guys. This does help. It brings a few other questions to mind though. "Centerline of the countershaft sprocket and the centerline of the swingarm pivot." Would that mean if they are located exactly one above the other,one behind the other, as well as side by side? Why would this make the back end wide? "at rest". Would that be on the center stand, kick stand or both? I'm thinking that the slack would be different by which stand the bike is on. I know the VFR Service Manual states to adjust when on the center stand. Does the slack differ between a warm chain compared to a cold chain? Sorry for all the questions. I'm rather meticulous. Perhaps too much in most cases. Link to comment Share on other sites More sharing options...
Monk Posted July 11, 2011 Share Posted July 11, 2011 Thanks guys. This does help. It brings a few other questions to mind though. "Centerline of the countershaft sprocket and the centerline of the swingarm pivot." Would that mean if they are located exactly one above the other,one behind the other, as well as side by side? Why would this make the back end wide? "at rest". Would that be on the center stand, kick stand or both? I'm thinking that the slack would be different by which stand the bike is on. I know the VFR Service Manual states to adjust when on the center stand. Does the slack differ between a warm chain compared to a cold chain? Sorry for all the questions. I'm rather meticulous. Perhaps too much in most cases. Side by side could make it wider. With the VFR C-stand the chain will be at the loosest ; Side stand is tighter but not a straight line yet ; Sitting on the bike will be closer to straight. On the c-stand measure 1- 1/4" to 1- 1/2". I made an L-shaped (coat hanger) wire so while I'm "sitting" on the bike I can see if the chain has any flex by sticking it on the bottom train(row) of chain and pulling up on it(this is after doing the measurement, and adjustment). It should show some movement but not much....How much is not much? That's why you do the measurement on the c-stand 1st. (use one of the pins on the chain to measure the inch with not the edge of the chain(less to think about). Turn the wheel and check the chain about every 10/15 links, if you find an area that's tighter than the rest, use that point for measurement and adjustment. Hot = Looser...........Check when cold.... always lean to the looser choice. Link to comment Share on other sites More sharing options...
Member Contributer CHUCK2 Posted July 11, 2011 Author Member Contributer Share Posted July 11, 2011 Thanks Monk. Is a chain made to be able to move from side to side or does that happen from usage? Link to comment Share on other sites More sharing options...
Member Contributer joneill Posted May 16, 2012 Member Contributer Share Posted May 16, 2012 I just noticed while flipping through my manuals that the Honda Service Manual procedure is to check and set the chain slack with the VFR on the center stand and the Cymer manual procedure has setting the chain slack with the VFR on the side stand. Both use the same chain slack measurements (20-30 mm). Both can't be correct. I've been setting the chain slack on the center stand, mostly because I am lazy and it is easier. Is the center stand method correct? (5th gen model if it makes any difference) Link to comment Share on other sites More sharing options...
Guest Posted May 16, 2012 Share Posted May 16, 2012 I know on a 3rd gen the owners manual says side stand. Link to comment Share on other sites More sharing options...
spud786 Posted May 16, 2012 Share Posted May 16, 2012 Thanks guys. This does help. It brings a few other questions to mind though. "Does the slack differ between a warm chain compared to a cold chain? Sorry for all the questions. I'm rather meticulous. Perhaps too much in most cases. NO, you'd have to get the chain to about 1200 degrees before the metal would stretch Link to comment Share on other sites More sharing options...
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