Chainring orientation question
04-14-10, 05:33 AM
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Chainring orientation question
Is there any general rule about the side of the chainring on which manufacturers stamp their logo and/or the number of teeth? On the large ring, obviously, it's typically on the outside--that is, facing right as you sit on the bike--so it's easy to read. Without thinking much about it, I'd sort of assumed that the same orientation applied to the inner ring of a double as well, even thought that means that it might sometimes be obscured by the bigger ring.
But the other day I was switching the rings on my Stronglight 93 from a 45-40 half-step setup to a 48-42, using a new 48-tooth ring that just arrived from xxcycle in France (good quality, apparently, and reasonably priced, though not a cosmetic match for the original.) Last year I had installed the 45-40 rings with both stampings facing right, but when I went to reinstall the 42, which was original to the bike--and therefore presumably installed as the manufacturer intended-- I noticed that the ghost marks on the ring from the crank spider clearly showed that it had been installed the other way, with the stamping facing left. More obviously, the chainring bolt holes are countersunk on the stamped side to acccomodate the heads of the chainring nuts.
So I guess I had it wrong. That may explain why I had some trouble with the chain sometimes coming to rest between the rings and spinning helplessly when downshifting--the original orientation places the "edges" of the teeth a little closer together, perhaps making that less likely to happen.
Live and learn. Any other observations on this?
But the other day I was switching the rings on my Stronglight 93 from a 45-40 half-step setup to a 48-42, using a new 48-tooth ring that just arrived from xxcycle in France (good quality, apparently, and reasonably priced, though not a cosmetic match for the original.) Last year I had installed the 45-40 rings with both stampings facing right, but when I went to reinstall the 42, which was original to the bike--and therefore presumably installed as the manufacturer intended-- I noticed that the ghost marks on the ring from the crank spider clearly showed that it had been installed the other way, with the stamping facing left. More obviously, the chainring bolt holes are countersunk on the stamped side to acccomodate the heads of the chainring nuts.
So I guess I had it wrong. That may explain why I had some trouble with the chain sometimes coming to rest between the rings and spinning helplessly when downshifting--the original orientation places the "edges" of the teeth a little closer together, perhaps making that less likely to happen.
Live and learn. Any other observations on this?
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Last edited by jonwvara; 04-14-10 at 05:36 AM. Reason: fix typo
04-14-10, 06:30 AM
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The Stronglight 93 that came on my 72 Moto has the graphics opposite like you learned, outside out, inside opposite. Devil is in the details, good you watch it when you reassembled!
04-14-10, 06:49 AM
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I have seen this also and I think that some of the rings may have just been on different sides when the machining process took place and they wouldn't just trash the ring because of it.
04-14-10, 08:02 AM
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The countersink tells you how to install it, but I've seen the rings installed both ways. Every 93 ring I've ever seen has been machined the same way, and I've seen a lot of them. I have three 93s myself.
04-14-10, 08:13 AM
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Right, and a good point. I should have been paying attention earlier. But what if there is no countersink?
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04-14-10, 08:27 AM
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also on some (mostly newer) there is a orientation to the crank. there is a little tab on the inside of the circle that should align with the crank arm.
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04-14-10, 09:07 AM
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Are the teeth symmetrical? If I recall correctly, the rings are milled from one side; that is, the countersink, the stamped logo, and the milling for the teeth are all on the same side, while the other side is flat. Do I have that right? If so, put the flat sides of the rings together, with the spider between them, and the stamped logos facing away from one another.
04-14-10, 09:21 AM
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Examine the machining of the teeth; see if one side is closer then the other. Choose the side best suited to your chain width and chainline.
If both sides are equal, find out which side the engraving is on, and put that to the inside, so someone can read it clearly from the left side.
-Kurt
If both sides are equal, find out which side the engraving is on, and put that to the inside, so someone can read it clearly from the left side.
-Kurt
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