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Chainring hitting chainstay. HELP(7 posts)

Chainring hitting chainstay. HELPHENRY K
Jan 8, 2004 7:55 PM
I am swapping some parts around on different bike builds and this is the second time in a couple of weeks that I have had this problem. I have a frame (Litespeed Appalachian Cyclocross frame)with a 68mm shell. I am installing a FSA compact crank 48-38 with a Shimano 6500 bottom bracket that is stamped 68. It also is 109.5 in length (I am not sure where that is measured from). Anyway the inside ring does not quite touch but it is so close that just putting a little pressure on the crank with my hand I can get it to flex enough for the ring to rub on the chainstay. When I described this similar problem with another bike a few weeks ago it was suggested that a spacer could help. I really don't want to go that route unless I have to. Does anyone have any suggestions on what I may be doing wrong? I have a triple btm. brkt. that I could use but I am afraid that it would effect my chainline. BTW, How do I check for the proper chainline on a double?
re: Chainring hitting chainstay. HELPwooden legs
Jan 9, 2004 1:35 AM
sounds like you just need a longer bottom bracket spindle. a thirty eight inner ring combined with a 109.5 spindle sounds like it should work though, unless the tapers on the spindle or the cranks are really worn in, which can make them slip on further than intended. i don't think a spacer would work very well in this case, i'd try a 113 bb spindle.
re: Chainring hitting chainstay. HELPjekakestrel
Jan 9, 2004 4:11 AM
Henry, I too had the same problem with my LS Appalacian set up. I received similiar advice about the spacers, and have used it successfully for the past two years.

Purchase a couple of fiber gaskets used normally in plumbing valves and add one or two to the drive side of the BB.

Regards,

Jerry
Henry! One more time, check your chain line.Kerry Irons
Jan 9, 2004 7:19 PM
You seem to have an abnormal fear of spacers. They are used all the time to correct minor misalignments. The thing you should really be worrying about is whether your chain line is correct (as suggested in the previous thread). Check to be sure that the center line between the chain rings hits the center of the cassette cogs. If your cranks are too close to the frame, the chain rings may well be biased toward the larger cogs, making for excessive chain anges in the smaller cogs. Check this and get it right with a spacer, if needed. If you are still seeing the rings very close to the chain stay, then you have a frame/crank incompatibility. I'm guessing that is not the case, but until you measure it, you won't know.
$Fear!HENRY K
Jan 9, 2004 8:29 PM
The reason for fear is that I visited 3 LBSs today and they did not have spacers and recommended that I purchase different bottom brackets$$$. They said not to use spacers! I spoke with the Crank manufacturer (FSA) and they told me to buy a longer bottom bracket. It looks like I either have to use a mtn. bike bracket to go slightly longer or the next step up is a 118.5mm which is for a triple. I have an extra 118.5 but it seems like there is more room than need be then. Believe it or not, this is a different bike than I spoke of a couple of weeks ago. Thanks for the help. Still open for more suggestions. Thanks.
Oh, and about that chain line?Kerry Irons
Jan 11, 2004 4:30 PM
So, once more, this time with feeling. IS YOUR CHAIN LINE GOOD? If it is, quit worrying about it or just use a spacer to get a little more chain stay clearance. If the chain line is off, would the change in BB length fix it, or throw it off farther in the other direction. The fact that these shops don't have/understand the use of spacers says a lot more about the shops than the technique. You use spacers to make fine adjustments (no more than 2mm or so) and you change the BB length to fix bigger errors. But you start with getting the chain line right. You're going to do that, right?
Yes!HENRY K
Jan 11, 2004 5:54 PM
Still looking for the spacers. Thanks