Posts Tagged 'Derailleur'

Incomplete cycle maintenance

Planet-X returned my Model B rear wheel on Tuesday with a new spoke and all trued up.  It was good of them to fix it free of charge and it’s nice to have it back so I can finally fix the bike up properly and get back on the road.  I dedicated the evening yesterday to bike maintenance so that I could ride today.

First I removed the front wheel and stripped off my saddle bag, lights and other attachments.  Then I removed the cranks.  I gave the bike a once-over with a soft brush to remove loose dirt, and used a slightly harder brush on metal bits.  Then I gave the whole frame a nice wipe over and cleaned up all of the components.  I replaced the brake pads, front and back.  I then removed the worn out bottom bracket and replaced it with a new FSA MegaExo with the help of a borrowed spanner (thanks Simon!).

After replacing the wheels and cleaning the chain and cranks, it was time to install the new rear derailleur, a Shimano Ultegra 6700.  This is a replacement for the previous Shimano 105 which was damaged as a result of a spoke snapping on the Planet-X wheel and getting dragged into the gear mechanism by the chain (it was quite an upsetting experience).

I attached the derailleur to the gear hanger, as described in the instructions, and set the right-limit screw so the pulley was directly in line with the smallest cog on the cassette.  I then attached the gear cable to the derailleur and attempted to shift to the largest cog to set the left-limit screw.  Shift one – nothing happened; shift two – nothing happened; shift three -nothing happened.  On the fourth shift I felt the cable tighten a bit.  The next few shifts produced some derailleur movement, but didn’t get me more than half way across the cassette.  I thought I must have been doing it wrong.

As I hadn’t gotten any movement on the first few shifts, I went back to the beginning and reattached the cable a little tighter.  But when I tried shifting across the cassette again, I got the same results.  I tried making the shifts with my fingers on the cable so I could feel it progressively tighten, but there was nothing for the first three shifts.  That got me worrying that there was something wrong with the shifter.  Could the shifter have been damaged by sudden cable pull when the derailleur was damaged?  I have no idea.  I’m quite inexperienced when it comes to shifter/derailleur mechanics.

After a lot of persistant effort, the cable finally snapped at the shifter end.  When I tried shifting the lever with no cable attached, it would only shift three steps in either direction, so I’m quite concerned now that I need to do a lever replacement as well as the rear mech.  I jumped on the CycleChat forums to see if I could get any advice and was told to get a new cable, thread it through the shifter without attaching it to the rear mech, and try shifting while pulling the holding the cable firmly in one hand.  I should be able to feel the shifter progress the full range in each direction.  I’ll pick up a new cable on the way home and try it tonight.

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