I normally have much love for my LBS, but I've moved recently and am a little unsure about this new one due to the fees he is asking.

I have a flip flop hub with a fixed gear (18 tooth) cog on one side, and a freewheel single speed cog on the other side. I need the fixed gear cog replaced. As I understand all you need to take this off is a special tool every bike shop would have. I assume the whole replacement process would take all of 5 minutes - quicker (like 2 min) for an experienced mechanic -- is this true?

The shop wants $50 labour to do this. Seems a little steep, I think! Am I right to think that this rate is unreasonably high?

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    This is true. At most this should be a 10-15 minute job, if you are bringing in the bike. Ask him what his shop rate is. Most US shops are around $100/hour. Also, ask him if there is a minimum labor charge. Last, many shops have a labor surcharge if you buy your parts online, and ask the LBS to install them, or if you bring your bike in dirty. Make sure you are not wasting his time with things which would give him a reason to "overcharge" you. Or if you always want everything done "right now!", he may be charging you for the delay to his customers who plan. Or he may be expensive. ASK him.
    – zenbike
    Commented Jan 4, 2012 at 11:32
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    Maybe I have a really nice bike shop, but many little things like this I've found they will do this without charge provided you buy the parts from them. This summer, my LBS put in a new stem, while I waited. They also installed the new pedals I bought. The mechanic didn't seem too busy when I was in, so maybe I was just lucky. However, I think that if I had brought in a part that I had bought online or at another store, there definitely would have been some kind of labour charge.
    – Kibbee
    Commented Jan 4, 2012 at 14:02
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    It is not unreasonably high. Fixed cogs are things which are swapped by track cyclists as often as 1 or 2 times per workout. The $50 charge is a way of saying you should really get the tools and do it yourself. It also is a way of the shop mitigating the risk of stripped threads (which may or may not be their fault), getting blamed for it and then having to replace a hub at their cost. In other words, I don't think shop is trying rip you off, they're just protecting themselves from the risk of a low-value operation which has a high cost if there's a screw-up.
    – Angelo
    Commented Jul 20, 2012 at 13:39
  • @Angelo Good point regarding the threads.. but still, a little high... Commented Jan 4, 2018 at 6:51

3 Answers 3


Ah the internet.

Answered my own Q:

It takes about a minute. Yay!

Watch at 2:13: Replace Fixed Cog (broken link)

Instead, try

For DIY: need a chainwhip and a lockring wrench / lockring spanner

...or a multi-tool with chainwhip & lockring wrench!


  • a VERY SUCCINCT explanation: youtube.com/watch?v=qtilQkz9FI0&feature=related Commented Jan 4, 2012 at 6:50
  • I can't think of a better way of putting it than Angelo did. Commented Jul 20, 2012 at 13:36
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    ...and then he deleted it. :/ Commented Jul 20, 2012 at 13:37
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    Yes, It's an easy fix. However if a shop told me that it would be $50 bucks, I'd tell them to stick it. If they told me it's really simple to do and sold me the tools to do it, then I would think they are awesome.
    – Benzo
    Commented Jul 20, 2012 at 14:02
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    The linked video is now private; is there another, equivalent video out there? Commented Jul 24, 2012 at 0:26

If you wish to do it yourself, go ahead but at the cost of how much the proper tools cost, how often you will be doing this yourself and how much time you have should also be a consideration. I have bought the equipment to do it myself several times over the years [lost them all of course!] and have done it myself but would rather have someone who does it everyday and have the tools to do it properly and save me time as well. I would say $50 is well worth it.


I've got a flip flop hub myself and haven't got any of those specialised tools, all you need is a screwdriver and a hammer. The lock ring is nothing more than nut that holds on the gear.

If you're replacing the cog, you might find that your chain might be worn too and might skip around on the new cog.

  • Thanks for the info. I understand that you'd knock the lockring out with the hammer and and screwdriver in one of the grooves of the lockring. Tell me, how do you get the cog off however? Commented Jan 6, 2012 at 4:15

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