I am a cycling newbie. My bike has 18 speeds with two chainrings in front and nine in back. I just did my first rear tire replacement. Most of that went well, however when I took it out for a short test ride and went through all the gears to make sure they were working correctly, I discovered that they weren't. The front derailleur is working fine, but the rear is stuck in first gear. I've watched the park tool video about adjusting the derailleurs, but I'd still like to know what might have caused this situation so I can avoid it happening again. I should also mention that during the process of changing the rear tire, I opened the rear brake because one crappy video on YouTube advised to "make sure" to do so. But my bike has hydraulic brakes and then they were stuck shut. I gently pried them open with a clean 2-in metal putty knife, and the brakes worked beautifully in my test ride. Could that have had any effect on the gear shifting? Any advice you can give would be greatly appreciated.

  • When you say "first gear" you mean the easiest one with the most teeth, or the hardest gear with the fewest teeth? Gear naming is all sorts of messy.
    – Criggie
    Sep 11, 2023 at 7:03
  • Some clear and well-lit photos of your bike would be helpful - one showing the rear derailleur area up close, one showing the whole bike from the right-hand side. You can add them with edit then hit the (insert image) button.
    – Criggie
    Sep 11, 2023 at 7:06
  • An assessment of the cable would be good thing to start after sorting out "first gear" terminology. I think it is more likely that the cable wasn't pristine and and just snapped or slid through the bolt during servicing and the RD dropped in its "relaxed" position which unfortunately is the hardest gear. Does the cable give any sign of movement when operating the lever, is there any kind of resistance when you press on it with your finger or does it just collapse/move easily?
    – DoNuT
    Sep 11, 2023 at 8:47

2 Answers 2


The brakes are probably not related to your problem - if the rotor was getting hung up then the wheel wouldn't be able to bolt in.

So what may have happened is that either your chain is somehow out of position as it passes through the derailleur, or you've undone a pinch bolt that holds the gear wire in place. Both could push the chain onto the highest/hardest gear cog with the fewest teeth.

If your chain is stuck on the easiest gear, then something has pulled a whole lot of cable from the rear derailleur. It may be your right-hand shifter is somehow damaged and not unspooling cable, or the cable is pinched in the tight position somehow.


Thank you Criggie and DoNuT for your rapid responses. I have taken my bike into a shop to get it back in riding order. I’ll get more info from the shop technician about what was going on and why the gears got so wonky. I’m also maintaining a file of all of your great responses to assist in case of problems when I do future rear tire changes.

Watching YouTube videos has also been helpful (and at times unhelpful) but what I really want is an IN PERSON bike maintenance class. It seem so incredibly basic; I mean, a metropolitan area of 1.4 million people should have some bike maintenance classes available, don’t you think? But NOOOO! I’ve searched and searched online, and nothing. Before Covid, there were a couple of classes available, but not anymore. Even the local Bicycle Society had no suggestions but calling each bike shop directly and inquiring if they offer classes! I guess I’ll be spending some time on the phone the next few days.

Again, thank you so much for your help. - Stevie

  • Good to hear! In case of doubt, let LBS fix and learn from it. BTW: Answers are mainly meant for constructive answers, the above is more suitable as a comment under the original question. If you get feedback from your shop about the actual problem, you can still edit it and add this as a self-answer. Somebody might still be helped by understanding what the problem was, a "stuck" RD is a common enough symptom. Cheers!
    – DoNuT
    Sep 15, 2023 at 6:57
  • @Stevie, at that size of city, see if you can find bike co-ops, they are similar to typical bike shops, but they mainly deal with used bikes and parts. The ones I'm aware of accept donations of used bikes for free only (so as to not contribute to bike theft). Typically in these, you can come in and work on your bike yourself, and the staff (and/or volunteers) will walk you through what you need to do, rather than doing the work for you. They have work stands, tools etc.
    – newroadie
    Sep 15, 2023 at 12:00
  • 1
    You appear to have multiple accounts. Same name as the questioner, but different reputation here as the answerer (which should be a comment, not an answer in this case).
    – Ted Hohl
    Sep 15, 2023 at 12:07
  • Maintenance courses can be hard to find out about even when they do exist. I hear about some on a facebook group for cyclists ion my city, others by word of mouth, and still others from the local authority, in a news feed I'm subscribed to. Local advocacy groups are good places to ask about training
    – Chris H
    Sep 15, 2023 at 13:12

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