timo888 

What has to be done to convert a BB to eccentric? Is it as simple as finding an eccentric BB whose outer cylinder has an O.D. that fits the frame? Or does the frame have to be cut and rewelded?
Thanks
T

Retro Grouch 

You need a different bottom bracket shell. If your frame wasn't designed for an eccentric, it's probably a deal buster.

anti.team

A while back, somebody posted a how-to build your own eccentric bottom bracket. It was a bit of a frankenstein but it could work. You'd have to do some searching on here and on google to find it.

dabac

Unless you're simultaneously swithching from Ashtabula to 3-piece I can't see how that's done.

timo888 

Thanks for the answers.

Would it be feasible for a bike maker to offer a bike in both standard and eccentric BB versions, one with derailleur and the other internal hub with rear disk brake?

T

Maxwell

Well, If you use a crank with a 24mm spindle, there's this thing

https://www.trickstuff.de/index.php?p=d116en1

probably needs a halflink sometimes.

dabac

Sure, but the market for the latter is so small that we're pretty much talking about bespoke stuff here.

carlton

I think the Trek SOHO is that way.

dwarner1

search the word 'eccentric' in the single-speed forum and you will find a couple of threads related to eccentric crank options.

timo888 

Thanks for the link!

timo888 

Not necessarily. With an eccentric bottom bracket, and both v-brake and disc-brake tabs, and vertical dropouts, the bike can be configured so that it has either type of brake front and/or rear (or a roller brake) with derailer, internal hub, or single-speed. Now your bike can be positioned for multiple market segments.

If you ride in a mountainous area and are going down long hills on paved road, or if you commute in wet weather, you might prefer disc brakes. If your road is a bumpy one, you might want an internal hub because there's less slop in the chain compared to a derailer setup. With an EBB, no need for a chain-tensioner. Harsh conditions...the internal hub is sealed against the elements. Put the internal hub on a folding bike and you solve a commonly reported problem -- derailers getting damaged when the bike is being transported. Ride on smooth level roads, then you might want v-brakes and derailer.

The same bike frame satisfies multiple riders/conditions, within the parameters of its geometry.
Regards
T

BCRider

There's a single speed 29'er at Nashbar I believe that comes in both "regular" and EBB forms for geared and SS use.

HillRider

Horizontal rear dropouts are a cheaper solution.

DeadSailor

thats pretty sweet!

timo888 

If horizontal dropouts are a 'cheaper' way to have the same frame be configured with either an internal hub or a cassette/derailer, they are also a lesser solution: repositioning the rear wheel in the dropout to tension the chain affects the brake alignment. If you were to use a chain tensioner as well, it hangs off the rear hub like a derailer and you sacrifice some of the benefits the rear hub brings; the tensioner can get bent during transport or when riding across an unmown meadow; the chain line has a little extra slop; the tensioner itself needs to be aligned.

Regards
T