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EBB and uneven tension

580 Views 5 Replies 4 Participants Last post by  perttime
I've looked around and couldn't find anything, but I have a problem on my new bike.
It's and IRO model 19 with and EBB, and when I pedal, the tension goes from tight to loose at the same point of each pedal rotation. Is my EBB not aligned in the shell correctly? or might this be a bigger problem. The chainrings are brand new and i'm sure they're at least 99% circular.
Thanks!
Adam
1 - 6 of 6 Posts
There is an inherent offset in all SS drive trains. What you are experiencing is totally normal. All SS do this to a certain extent.

Consider this. The drive train is all made up of concentric circles. Cogs, bearings for hubs/bb's, crank arm bolt holes etc. If all of these parts are all made to a 99% perfect position, you'll have the compounded 1% error of each of those parts to the end result. Geared drive chains have the same issue, only the rear der take up all of the slack.

Really, what you have is nothing to worry about. Tension the chain properly at the tightest spot and you'll be good. So long as the tight and loose issue is not enough to have your chain fall off or skip, you'll be fine. Ride and enjoy.
Ok, that makes sense. It doesn't seem like enough for the chain to fall off, but I thought it might be something more.
Thanks!
benwitt11 said:
There is an inherent offset in all SS drive trains. What you are experiencing is totally normal. All SS do this to a certain extent.

Consider this. The drive train is all made up of concentric circles. Cogs, bearings for hubs/bb's, crank arm bolt holes etc. If all of these parts are all made to a 99% perfect position, you'll have the compounded 1% error of each of those parts to the end result. Geared drive chains have the same issue, only the rear der take up all of the slack.

Really, what you have is nothing to worry about. Tension the chain properly at the tightest spot and you'll be good. So long as the tight and loose issue is not enough to have your chain fall off or skip, you'll be fine. Ride and enjoy.
So in other words: "tolerance stack-up" I always wondered why that was. Wonder if anyone ever tried to make a singlespeed conversion using a biopace ring :lol:
Arby said:
So in other words: "tolerance stack-up" I always wondered why that was. Wonder if anyone ever tried to make a singlespeed conversion using a biopace ring :lol:
I had a friend of a friend who made a fixed gear with a biopace and PVC handlebar, that didn't end well...
It is possible that the chainring is just slightly off and it can be fixed:
http://www.sheldonbrown.com/singlespeed.html#tension
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