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Discussion Starter · #1 ·
While I was riding on a trail, my shifter got stuck and it won't shift! I suspect the cable is snapped. I don't lubricate the cable coming from the shifter, so I think that's what caused it to snap. :madman: My bike is a TREK 3900, and I need a tutorial reguarding lubricating the cables on the shifters, because I'm too damed scared I'll break something......
 

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ravingbikefiend
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If nothing is jammed in the derailleur (this can cause a freeze up) then you'll have to remove the cable from the housing and most likely have to disassemble the shifter... the cable could be frayed or the shifter itself could be buggered.

Undo the screw/bolt at the derailleur to release the cable... you will want to cut the end of the cable with a good set of cable cutters to get a clean end that will pull through the housing.

Once the cable is free of the housing you can inspect it for damage and if it's jammed in the housing and won't move then you'll know that the break is inside the housing. If the cable comes out and is free of damage then the problem wil lie within the shifter itself and it could be as minor as a slack cable jamming itself in the mechanism or an internal cable break. This is where the cable sees a lot of bending stress and where it is most likely to fail.

If the break is inside the housing and the cable can;t be removed you will have to replace the housing.

Knowing what kind of shifters you are using is important as then I could tell you how to take them apart and reinstall a new shifter cable...thumbies are easy, pod shifters can be a pain, and grip shifts are the work of Satan.

I lube my cable housing with silicone spray that I shoot into the open end of the housing. you can also use light grease or oil on the cable before you slide it through or readily available WD40.

My bet is that the problem is going to be inside the shifter or right at the housing end by the derailleur.
 

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Discussion Starter · #3 ·
Thanks! I'll check the cable if it even moves when I remove it from the deraileur. BTW, I think the shifters are "thumbies", but I'm not sure. Here's what the TREK official website says:

TREK said:
Shifters: Shimano EF50, 8 speed
 

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ravingbikefiend
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The EF50's are an integrated shifter pod and brake so the shifter will need to be disassembled to reinstall the shifter cable. These have the gear your in displayed in a little window... yes ?

Here's a link to the shifters I thkn you have on your bike.

http://www.bikepartsusa.com/product_info.asp?f_c=Shifter&cp=1&p=01-130124

Thumbies are the old style levers which make cable replacement uber simple as they feed into the shifter externally.

I love thumbies for their simplicity, durability, and ease of service.
 

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Discussion Starter · #5 ·
Yes, those are the shifters, but they're actually 8-speeds. I love how the sporckets have the individual speeds closely geared.....

I'll check the cable later, because I'm too dam lazy (and tired) to get off my butt.....

I have very bad experiences w/ thembsies, as they always broke on me......
 

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You really don't need to lube your cable. It probably snapped because you got something jammed somewhere. It's good to change our your cables and housing every now and then, but I doubt not lubing the cable alone caused the cable to break.
 

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ravingbikefiend
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I agree with the lack of lube causing breakage... if the housings become contaminated with dirt and moisture it can cause rust which will result in the individual cable strands breaking off and jamming the system.

I service a lot of old bikes and a common problem with older ladies bikes is that the rear cable turns upwards as it comes to the brake and is an excellent receptacle for water.

Lubing your cables is merely way to extend the service life as this protects them from rust.

Another good idea is to run a continuous housing from the shifter to the cable stop as this decreases the number of points where contaminants can enter and makes for smoother running cables.
 

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Sixty Fiver said:
I agree with the lack of lube causing breakage... if the housings become contaminated with dirt and moisture it can cause rust which will result in the individual cable strands breaking off and jamming the system.

I service a lot of old bikes and a common problem with older ladies bikes is that the rear cable turns upwards as it comes to the brake and is an excellent receptacle for water.

Lubing your cables is merely way to extend the service life as this protects them from rust.

Another good idea is to run a continuous housing from the shifter to the cable stop as this decreases the number of points where contaminants can enter and makes for smoother running cables.
I see.... I stand corrected. I'm a cable clean freak myself so it was probably hard for me to comprehend cables getting so old they would rust. I personally change out my cables whenever I feel they're even the slightest bit sticky. I also run teflon coated cables as well. I was told lubing the cables makes them sticky so I never got into the habit of doing so.
 
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