Chain tensioning by moving the wheel forward or back in the droputs
nate said:
For chains that do not have a master link, I am curious how one removes a rear wheel on a fixed gear bike that has track ends without breaking the chain. Do you just leave space to slide the wheel towards the front of the bike in the track end and then slip the chain off the cog after creating some slack? Do most people simply use a chain that has a master link of some sort?
I have read that it is possible to remove the chain sometimes without even moving the wheel and that sometimes it is necessary to move the wheel forward. I am curious what the experienced fixed gear riders usually do and if it is accurate that a properly tensioned chain still can be removed (or put back on) without moving the wheel.
I think you've actually answered your own question. Typically, the chain is sized so that it can be slipped on and off with the wheel all the way forward, and then the wheel is pulled back to tension the chain.
Keep in mind that the only way for a track rider to change gear ratios is to change the size(s) of either the front chainring or rear sprocket (or sometimes both). It is not desired to keep breaking the chain to length or shorten it as the chainring/sprocket sizes are changed, so the slots in track dropouts are intentionlly made long so that they can accomodate moving the wheel forward or back as necessary to tension the chain with different chainring/sprocket ratios. Of course, there is a limit on how much change in chainring/sprocket size can be accomodated by dropout slots, but given the relatively narrow range of gearing used for most track riding, moving the wheel forward and back in the slots to accomodate gearing changes generally works fine.
Road fixed gears often use a flip-flop hub, with different sprocket sizes on each side of the wheel. The gear ratio can be changed by simply flipping the wheel from around to the other sprocket. The only way this really works on the road is if the wheel is moved forward or back in the dropouts as needed for the two sprocket sizes - with a little slack left over so that the chain can be mounted/dismounted with the wheel all the way forward in the slots. (Side note: This setup can be used to dispel the myth that the reason for horizontal dropouts on road bikes is so that the wheel can be moved forward or back to change the wheelbase and the handling of the bike. If you ride a flip-flop hub and regularly move the wheel forward and back to accomodate different sprocket sizes, you'll realize that a centimeter or so difference in chainstay length had no real affect on handling.)