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Eccentric BB?

Old 07-04-20, 05:35 AM
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Tandem Tom
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Eccentric BB?

Yesterday while working at the shop I had a bike in the stand with the above. So it got me thinking. If you were wanting to build up a bike with an IGH would you use an eccentric BB or sliding rear dropouts? And why?
Thanks!
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Old 07-04-20, 07:25 AM
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Doug Fattic 
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Originally Posted by Tandem Tom View Post
Yesterday while working at the shop I had a bike in the stand with the above. So it got me thinking. If you were wanting to build up a bike with an IGH would you use an eccentric BB or sliding rear dropouts? And why?
Thanks!
Tom it is much easier for an amateur builder to make a frame with horizontal long slot dropouts. This is because it is not necessary to nail exactly the chain stay length. You can get it approximately right by sliding the chain stays in and out of the BB shell’s sockets. With an eccentric shell it is necessary to get the miters and chain stay length just right. That is made much easier with machine mitering and an expensive fixture.
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Old 07-04-20, 07:51 AM
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unterhausen
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Back when people were building more single speed bikes, this was a big decision people had to go through. I think a lot of builders did a couple of eccentrics and then got tired of the creaking complaints and switched to sliders. It's a pain to get an eccentric bb now, unless Nova has one and I've forgotten.
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Old 07-04-20, 05:04 PM
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Andrew R Stewart 
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Good timing as the frame I am waiting time to finish will have an IGH. No horizontal slotted drops, no BB eccentric. I will use a spring loaded chain tensioner. Or is that wrong? Why? because I have experienced sliders and hingers that slip and creak and still want a disk set up. Andy
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Old 07-05-20, 05:09 AM
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So to further my education a follow-up question. Doug you mentionef long horizontal dropouts. What about the sliding dropouts that are a seperate "piece"? My wife's touri g bike has these.
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Old 07-05-20, 05:42 AM
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Sliding or Rocker dropouts would be my preference over an eccentric BB. Sliders and rockers have their issues too, but the Paragon sliders are the best in terms of preventing slipping of the insert. Between the double bolt washer and the adjustment bolt at the front, they don't move after you set them. The cheap cast sliding dropouts are not so great in terms of preventing the insert from slipping in use.

Paragon rockers are good, if you get the Titanium 12pt bolts with them. The steel bolts that come with the dropouts do not hold up to the torque necessary to prevent the drive side from slipping forward under heavy pedaling loads, such as climbing while standing. The hex in the bolt will strip out before you can get them tight enough.
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