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Chain Bumping the Chainstay?

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Chain Bumping the Chainstay?

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Old 03-12-18, 10:15 AM
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StarBiker
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Chain Bumping the Chainstay?

Like when you come of a curb on the sidewalk. How common is this on triple cranks. Really common I guess. What bikes have the crank positioned a little lower to prevent this. Or the drive positioned a little higher. Curious.
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Old 03-12-18, 10:26 AM
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I have 2 bikes with triple FD's and neither exhibits any "chain bumping on the chainstay." Possibly the chain on your bike is not correctly sized.
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Old 03-12-18, 12:02 PM
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Cannondale Adventure from 02', and a Gary Fisher Cobia from 09'. Both are in perfect condition, and both do this. I thought about the incorrect bike chain size but I have had a few bikes do this.



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Old 03-12-18, 12:18 PM
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Chainstay slap is pretty common when you're riding in the smaller chainrings and smallest cogs, as you apparently do from the pictures. Find the same gear combination with one of the larger chainrings, and the chain will be farther away from the chainstay. Problem solved.
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Old 03-12-18, 02:00 PM
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Originally Posted by StarBiker View Post
Like when you come of a curb on the sidewalk. How common is this on triple cranks. Really common I guess. What bikes have the crank positioned a little lower to prevent this. Or the drive positioned a little higher. Curious.
completely normal, clutched rear mechs help a great deal but you will still hit... thats why almost every bike comes with a chain stay protector.
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Old 03-12-18, 02:26 PM
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Chainstay slap is more likely to happen when you have a lot of excess chain flopping around. Not only does that elongate the length of chain from the bottom of the chainring to the rear deraileur chain tensioner, but the tensioner is not tensioning ad hard.

So how do you keep the chain tension higher and less chain flopping around?

1- make sure your chain is not too long (look up instructions for “big-big plus one chain length”)

2- Use bigger cog and chainrings when riding through rough stuff. With a triple you want to be in the middle or (best yet) the big ring.

This is less of an issue with doubles becuase you are always in either your biggest or 2nd biggest ring. There is no 3rd biggest ring that gives you so much chain slack (i.e., the small ring on a triple).

With a single ring setup, you are always in the biggest ring.

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Old 03-12-18, 03:42 PM
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Originally Posted by ThermionicScott View Post
Chainstay slap is pretty common when you're riding in the smaller chainrings and smallest cogs, as you apparently do from the pictures. Find the same gear combination with one of the larger chainrings, and the chain will be farther away from the chainstay. Problem solved.
You just verified what I thought. It's not like I am going off curbs every few feet. Was just curious if there are different builds that prevent this. Different frames. Crank sizes.......
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Old 03-12-18, 05:44 PM
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Originally Posted by StarBiker View Post
You just verified what I thought. It's not like I am going off curbs every few feet. Was just curious if there are different builds that prevent this. Different frames. Crank sizes.......
The only frames I know of that really do much to prevent this are some with elevated chain stays, where the top of the chain goes under the chainstay rather than over it. I am inclined to think this is not the reason for elevated chainstays, but rather a byproduct.
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Old 03-12-18, 06:20 PM
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No complaints. Just was curious. I have never owned a 29r, and I thought I would not keep the Gary Fisher but have thoroughly enjoyed riding it. Almost all pavement. Anyway....maybe I will spend some money someday? Nah.
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Old 03-13-18, 03:46 AM
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There are a lot of things you can use to wrap your chainstay with and protect it and quiet it down. You can buy a chainstay proctor or make one out of an old innertube but my favorite so far has been

https://www.amazon.com/3M-Scotch-Sea.../dp/B0010XFTQ6

Just put a layer of that down over top the clear stuff your bike already has from the factory. The clear stuff keeps the paint in decent shape but it doesn't do much for the noise.
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Old 03-16-18, 12:00 PM
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@StarBiker almost 900 posts and this is a question?
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Old 03-16-18, 03:49 PM
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Originally Posted by grubetown View Post
@StarBiker almost 900 posts and this is a question?
116 posts and not saying anything.
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