Single Speed Horizontal Dropout

This is a guide to Single Speed Dropouts and Chain Tensioners.

About Chain Tensioning

On a geared bike the rear deraileur keeps the chain tight.  On a single speed bike, as you know there is no rear derailuer so we need to find something to keep the chain from becoming loose and bouncing off when you pedal or go over bumps.

There are 3 main ways to accomplish this:

  • Single Speed Rear Dropouts
  • Customized Bottom Bracket
  • Chain Tensioner

Single Speed Rear Dropouts

Single Speed dropouts need to have a way to adjust the rear wheel horizontally (as opposed to vertically) so that the chain can have the appropriate amount of tension.

Horizontal Dropouts

In the image below you se how the rear wheel can be moved forward or back to adjust the chain tension to the correct amount.

Single Speed Horizontal Dropouts

Eccentric Bottom Bracket

An eccentric bottom bracket when rotate in the frame will create more or less tension on the chain.

Looking at the image below you can see how the hole for the cranks is off center, you can imagine the cranks moving forward or backward, thereby adjusting the tension of the chain.

Eccentric Bottom Bracket


This is a patented design


Niner – Biocentric Bottom Bracket
Niner Biocentric 30 Bottom Bracket

Wheels Manufacturing

More Posts about Eccentric Bottom Brackets

Chain Tensioners

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