All About Dropouts
September 29, 2008 by Matt Brady
Filed under Uncategorized
Dropouts are the part of your bike frame where the wheel’s axle rests (See picture). Different dropouts let your bike do different things. There primary purpose is to keep your wheel in place and hold tension on your chain.
Standard Drop Out
The standard drop out is, most common. It is just a slot that allows the axle to rest. These almost always include a derailleur hanger for mounting a rear derailleur. Unlike the other styles of drop outs they don’t allow for chain tension adjustment. For standard drop outs a rear derailleur or other device acts as a chain tensioner in order to keep the chain from skipping over gears
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Horizontal Drop Out
Horizontal drop outs, also called track drop outs, are usually found on single speed specific bike frames. These allow for the wheel to be moved backward or forward in the drop out to get the perfect chain tension. A chain tensioner, also called a chain tug, fits inside of the drop out and setscrews adjust the tension. Sometimes these will include a derailleur hanger to mount a rear derailleur, but it is rare.
Front Facing Horizontal Drop Out
Front facing horizontal dropouts are angled and allow the chain tension to be adjusted a bit. These are common on older bikes to help get the tension perfect. They work well for single speed applications as well, and because of the angled design of the dropout, the tension will pull against the frame and the quick release. That means that a quick release can usually hold the tension on the chain without slipping, whereas a horizontal dropout usually requires a chain tensioner or bolt-on hub. With a normal horizontal drop out, the chain pulls directly against the quick release. These almost always include a hanger to mount a rear derailleur.
There are also all kinds of hybrid designs on the market: Everything from drop outs that morph from standard to horizontal, to strange eccentric drop out designs.
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This post was written by:
Matt Brady - who has written 24 posts on Mountain bike product reviews, bike builds, trail reviews, forum, and tips – MTOBikes.com.
Born and raised in the Arizona desert, Matt loves all things outdoors. Always consumed by a passion to bring information based on different perspective he has pursued writing as a means to spread his approach to a variety of topics. Check out Matt's blog here: http://www.themusicmatcher.com/mattsworld
[...] If you do not already know, dropouts are the parts on your frame that the axles on your wheels sit in. There are three major types of [...]
Thanks for posting a pic of my eccentric dropouts. I worked long and hard on them. Also the rear brake is connected to the 12mm thru axle not the frame, and self adjusts.
Whooops….
Track frames have track ‘forks’ where one would find ‘drop outs’ on a road frame… No such thing as a ‘track drop out’….. (ref. Sheldon Brown, et al)….
Know someone with a lathe ? Can take a standard track hub and make it into the equivalent of an ENO hub….. not counting labor, oh, about $20….
Need a lathe though :-)
Red
Can this part of the bike be easily replaced? I had a little accident involving my dad’s bike and my car and now I’m having to think about how to fix it. I think it’s the dropout part that is a bit bent but it’s affecting the whole bike so I’m just trying to find out now what the best thing to do about it would be.