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I am trying to diagnose my issue. I commute to work about 14 miles round trip per day 4 or 5 days a week. I have some hills and I also cross a 2 mile farm via dirt road. I have put hundreds of miles on it since a tune up.

Lately from a stop at a light, when I apply pressure to start off the chain will skip. It simply pops off the rear derailleur and will not let me move forward. I am not a bike mechanic but I can learn quick. I am not sure how to diagnose the problem or even fix it. I can make this issue happen very easily by starting from a slow or stopped and pushing hard or riding up and pushing down on the pedal. The problem does not occur if I push lightly and start off as softly as I can. I can give more information if required.

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    You might want too google (or search here) for "chain stretch" and also how to check for wear on the gears.
    – Chris H
    Dec 14 '16 at 16:41
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    What is the mileage of the chain, the rings and the cassette?
    – Carel
    Dec 14 '16 at 18:45
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    I don't quite understand what pop off the rear derailleur is supposed to mean.
    – Batman
    Dec 14 '16 at 19:27
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    It would also be good to know whether there are specific gear combinations causing this. If you are on big-big or small-small combinations you may find that back-pedalling to get the pedal where you want it is partially changing the gear.
    – Chris
    Dec 14 '16 at 23:08
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    My guess is chain stretch or cassette wear. Try and provide an image of the cassette, derailleur and/or chain. Especially if it has hundreds of miles with out service on it.
    – Nate W
    Dec 15 '16 at 0:24
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In my experience, chain skip can be caused by various factors, some are easy to fix and some are more difficult. Lets work our way down.

1: dirty/dry chain. A chain that is not properly cleaned and lubed will cause shifting problem. Get a good chain cleaning tool and de-greaser and clean your chain really well. Then apply a good chain lubricant generously. Afterwards, wipe as much of it off as you can with a dry rag. It is important to use a chain lubricant (not wd-40 or something like it), that is meant to not collect dust. It is also important to wipe off the lube when you are done. You won't be able to get it out of the pivots - which is where it counts. This will fix most shifting problems.

2: Stretched shifting cable: If you recently had your bike tuned, it is likely that the rear shifting cable was replaced. New cables will stretch. The cable tightness will need to be adjusted after a month or so of riding. Either research how to do this tuning or take it by the bike shop that tuned it - they probably won't even charge you.

3: Worn chain: Chains wear, and they wear differently based on how they are used and maintained. A worn chain won't engage properly with the teethe of the cassette and will cause major shifting problems. If you are serious about maintaining your bike, you will need a chain checker. I personally like this one (https://www.amazon.com/gp/product/B001AYMR7Y/ref=oh_aui_search_detailpage?ie=UTF8&psc=1)

4: Worn cassette: If you change your chain on time, a cassette will generally last in the order of 3-5x chain changes - but eventually it will need replaced. There are plenty of resources to help with that (http://www.artscyclery.com/learningcenter/determiningcassettewear.html)

5: Old cables: Shifting cables and/or housing that are old and potentially frayed or rusted will cause shifting problems. Likely, though, this will have been addressed during your tune-up. You might want to verify though.

6: Other: Those mentioned above are the most likely culprits. However, there are other reasons that are more advanced to troubleshoot. These include, but are not limited to; a bent dérailleur, poor shifting adjustment, a cassette not properly tightened and a bad a bad chain link.

I suspect that if you address items 1-3 in order you will find that your problem goes away.

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  • I got the issue after riding under a rain so I think number 1 is the problem. I will check that. Aug 17 '18 at 5:12

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