105 rear Not Shifting

I have a Fuji Roubaix with Shimano 105 8 speed group (double chainring) that I've had for awhile. I also have not been riding it for about 18 months - injuries, work, etc.

Today was gorgeous, my ankle is finally up to riding and I thought I'd take a short ride. When I got on the bike it was in the lowest gear on the rear cassette - fine for starting out - but I couldn't get it to shift to a higher gear. The chainring shifter works fine.

Does anyone have any thoughts? Is this a fixable problem or am I looking at some very expensive replacement parts?

Thanks a lot.

Remember HOW a rear derailleur works. The upper chain guide shifts left and right forcing the chain left or right and thus over whatever gear you want to be in. This guide is controlled by your shifting level on your handlebar. To work the cable must be tight. The cable has a plastic reinforced coating that permit the metal cable to be bent from the Shit levels on the handlebars to the Derailleur. The cable extends from both end of the plastic Cable. The end of the Plastic Cable fit inside stays from the Front Shifter and from the derailleur. It is rare for the Plastic cover to be bad (it can be, but rare) most of the problem is from the stays to the Derailleur with the shift levels being a distant second.

Given the above (and most shift levels have their stays inside the shift levels so no adjustment is possible around the shift able) there can be three things wrong:

1. The cable is OFF its stays, i.e. the cable is lose. The stays holds the plastic cable in place and guides the metal cable to the Rear Derailleur. Thus if the plastic is off the stay, put it back on and the cable will be tight.

2. The cable has stretched so that you need to loses up the clamp holding the cable to the Rear Derailleur pull the cable tighter and then clamp down the clamp, making the cable tight.

3. The cable is damaged and needs to be replaced. If this is the case, it generally is caused when a bike hits something (or something hits the bike0 Smashing in the cable housing so that the cable can no longer move within the Plastic Housing.

If the problem is the cable housing I would have someone else replace the cable. Cost about $20-25 dollars. The main reason is that to work on the cables you need to work on the bike on a bike stand which runs $200-300 for a good bike stand. You can do it without a bike stand, but then you are working upside down (i.e. the bike is upside down) but it is easier to work with the bike held by a bike stand as you adjust the new cables to fit the bike.

and no evidence of fraying.

Did I mention that these are 'brifters'? Combined brake levers and shifters?

The cables and housings are sound.

And that may mean a new derailleur or something similar. Derailleur run about $50 dollars, but I would take it to a bike shop to do the work. You can do it, but not worth the effort. For a price close to the price of the parts you can have the bike shop do the work.

Most bike shops will take in any bike, even department store bikes. Furthermore the Shimano 105 series is very common, so almost ALL (if not ALL) bike shops know about them.

that are gummed up.

I've been trying to avoid the bike shop - two very good ones - hoping this was a simple fix.

Oh well, so it goes.

It's a good frame and the rims are sound, so maybe I'll just change the whole group to the bottom end Campy or spring for an Ultegra group.

It is the cables - they are gummed up.

Did the bike shift ok last time you rode it 18 months ago?

Bikes just don't stop working as the BA pointed out in previous posts on this thread you need to check your cables - he covered all of the possibles - except for gummy/seized cables.

Do this before you mess around with those shifters.

Un clamp the cable from the 105 Rear Der. now with the end of the cable in your hand - holding on to it where the Rear Der. was just clamped on to.

Now go through your gears while maintaining tension on the cable with your other hand.

Does the cable shift/move freely with each shift?

If it doesn't then it is probably a seized cable - bikes when they sit for a long time - even garages get condensation on them(unless stored in doors in a controlled environment)this condensation is what destroys cables and their ability to shift freely inside the housing.

If you think it is still your shifters take all of the housing off of the cable and take the cable out of the braze ons all the way up to the shifter. Leave the cable hooked up to the shifter. Now with the cable still in the shifter, shift the shifter while keeping tension on the cable like you did before when the cable was wired to the back of the bike.

Does the shifter shift freely with the cable still in there?

If not then your shifter is bad or not right.

My money is on a seized cable/housing - that is the number one problem associated with your description especially since the bike sat for 18 months.

Let me know - if it is cable and housing then the shop should be able to whip that out for ya for about 10-20$ depending on the shop.

PS remember the cable and housing can show no signs of wear or fraying and still have this problem.

Hope this helps and if I am wrong I would be curious to see what the problem was/is - dogs can always learn new tricks. :)

I just this minute went and fooled around with the rear cable sleeve that attaches to the derailleur ( The bike was up on the rack ). Didn't disconnect anything, just fiddled around with the sleeve then tried the brifter and turning the crank. It shifted up and down the range. It may well work now. But I'll have to take it out on the road to check.

Again, thanks for the advice.

Happy cycling!

:rofl::thumbsup: