I had an old general purpose bike that I wanted to use exclusively with my new turbo trainer. I ended up taking it apart almost completely and of course I did not take pictures so re-assembly was a pain and still have issues now.

Gears don't really change in many positions and result in different types of noise. One gear position worked fine so I just used that. Now however after about 200km cycling over a couple of months it started to make a noise almost like metal sparking. It's not constant but very frequent and gets worse with higher speed.

Cleaning, oiling, using WD-40 did not resolve the issue. Neither did inflating the tire (it was very low psi). I don't see any obvious wear from friction or other damage. The axis at the center of the wheel gets really hot after 10 min at least not sure if this was always the case and if it's normal.

Can anyone see any issue in the pictures? What else is worth trying to fix this?

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  • The noise sounds like you need to adjust the rear derailleur. There are plenty of YouTube videos explaining how to do that: this morning, I used the ones at GCN and Park Tools to adjust my front derailleur and I assume their videos about the rear are equally clear. The overheating issue sounds like your bearings are shot. Commented Mar 20, 2018 at 17:50
  • Will try adjusting derailleur next. How warm would you expect the central axis to get normally at about 100W power output? I did think it was more difficult to maintain 100W after noise started so bad bearing sounds likely.
    – DominicM
    Commented Mar 20, 2018 at 20:45
  • WD-40 is more solvent than oil. If you tried to clean wheel bearings with it, now it good time to disassemble and grease them. 100W is nothing to bearings that are in any shape.
    – ojs
    Commented Mar 20, 2018 at 20:50
  • WD-40 was just for the chain to see if it was the issue, I know it's not lubricant as such though it works short term. I know 100W isn't much, I just want to know what is the expected behavior if it's working as normal. I mean for all I know it should get somewhat warm even if it's working perfectly.
    – DominicM
    Commented Mar 20, 2018 at 20:57
  • The temperature difference should be something that's noticeable with lab equipment, not human noticeable.
    – ojs
    Commented Mar 21, 2018 at 6:23

1 Answer 1


First thing to do is check the rear wheel bearings. Get the rear wheel out and inspect the axle. If there is any play between the axle and hub or roughness or 'notchiness' when you turn the axle, the bearings are worn out. If you have a cup-and-cone style hub the bearings can be serviced. There are several online resources that show you how to do that. I recommend Park Tool's articles and YouTube videos. Some hubs have replaceable cartridge bearings.

If the gear shifting is not working, that could be due to a number of different things, including the issues with the shifter, but most likely poor indexing adjustment. Again, there there are number of online resources that show you how to troubleshoot and adjust indexing.

I note you have an older Shimano Tourney, which is is lowest level Shimano groupset, which does not offer great shifting in the first place.

  • I took apart the back wheel. One of the ball bearings is stuck between the outside of the ball bearing cup and the cassette. The ball bearing cup is pretty indented by the bearing. Waiting for the tool to take off the cassette for now.
    – DominicM
    Commented Apr 7, 2018 at 13:53

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