give me a refresher on rear derrailer adjustments?

vash · vash's Garage

been a looooonggg time for me. we have a local shop that has an annual 50% off bike tune. so i havent touch a bike for years. but i can only take one bike in. but the cost is going way up. like car tune up levels. ok, i exaggerate. but $90 before the 50%..seriously? this is without parts.

remind me? adjust the upper and low stops to come off perfectly with the associated chain-ring. and then adjust cable tension so all the gears click perfectly..right?

i can get it perfect on the stand, but occasionally, i get a ghost shift while actually riding the thing.. or it wont shift..until later. maybe my chain needs replacing? i dont have a chain gauge. i go one way or the other on the cable tension and it gets worse.

oh, any quick tips to remember which screw you turn for the lower chain ring and vice versa? i seem to always twist the wrong one at the wrong time.

i refuse to join a biking forum.

all the big brains are here anyways.

greglepore · 09-12-2013, 10:12 AM

If its the rear mech you're talking about, you have the basic procedure correct, but I'd rather have you tweek the cable tension on one of the middle cogs so that you have perfect alignment there of the upper jockey pulley and the cog.

There is also a b screw that rests on the derailler hanger, you can adjust that so that the jockey wheel is close but not binding the chain on the biggest cog.

Ghost shifts may indicate a worn chain or a worn cogset or both-if chains get excessively worn they take out the cassette-I replace mine early and have yet to wear out a cassette.

look 171 · 09-12-2013, 10:12 AM

put the chain on the little rings and small cog. Put shifter to smallest cog position and loosen cable to RD and pull tight and slightly crank down cable clamp. Shift up all the gears and back down. If the chain jumps off the smallest cog, you must adj the stops to prevent chain from going into the frame. Do the same to the large cog. Loosen cable to FR. Put chain on the small ring tighten clamp and shift up to the large one. Make sure the stop screws are set so it wouldn't fall out of the crank. If the RD jumps a gear, use the fine adj barrel to move the RD so the chain stays put. Adj it more using the barrel to eliminate chain noise and alignment.

Oil the chain and it will run super smooth. I usually run an extra link. Extra link allows the chain to run quieter and smoother. Vash, get a new chain. An old chain is not worth riding. The big guy down there isn't hurting. When it breaks, you are more then likely off the saddle.

Re-adjust the FD to it sits about 1 mm above the large ring and it is lined up perfectly with the ring, flat.

look 171 · 09-12-2013, 10:15 AM

Check the hanger. it might be out of whack. Stand behind the bike and look at the hanger and you should be able to see if its straight or not. There is a special too to measure that. Out in the field, I ususlly take a large tool and bend it back into alignment.

Flat Six · Flat Six's Garage

Vash -- what kind of rear derailleur do you have?

wrpeterson · 09-12-2013, 10:50 AM

This is perhaps the most comprehensive site for bicycle repair - good stuff!

jyl · jyl's Garage

Turn the barrel adjusters to most of the way in before you set anything. So you have more range for field adjustment.

red-beard · red-beard's Garage

Shimano

Front: http://techdocs.shimano.com/media/techdocs/content/cycle/SI/105/FD-5503-5504/SI-57Z0C-En_v1_m56577569830603724.pdf

Rear: http://techdocs.shimano.com/media/techdocs/content/cycle/SI/105/RD-5500-5501/SI-5TK0D-En_v1_m56577569830603908.pdf

intakexhaust · intakexhaust's Garage

OK Vash-
No bike forum to join, simple explanation and you'll love the opening sentence on the word 'derailleur'

The late Sheldon Brown site:

Derailer Adjustment

Now get out there and ride!

sammyg2 · 04:20 PM

I believe the technical term is "disraeli gears".

Don Ro · 09-12-2013, 04:21 PM

What a forum!!! Ask and you shall receive.
.
"all the big brains are here anyways."

Don Ro · 09-12-2013, 04:21 PM

When did Sheldon Brown pass?

John Rogers · 09-12-2013, 07:28 PM

Back when I was racing, the gears that mattered were highest gear and the two lowest gears. So once things were lined up, make sure that large chain ring and small rear sprocket are lined and there is no abnormal noise. Then small front chain ring and largest and next to largest rear sprockets shift into smoothly and there is no noise. Depending on how much you ride, a new chain every year saves the gears. I was riding 450 miles a week more or less, plus races so my daughter and I used a chain a month.

Why the two lowest gears......so when you start up a bad hill and you are tired you never ever start out in the lowest, always save that one for getting to the top!

look 171 · 09-12-2013, 07:33 PM

Quote:

Originally Posted by john rogers

Back when I was racing, the gears that mattered were highest gear and the two lowest gears. So once things were lined up, make sure that large chain ring and small rear sprocket are lined and there is no abnormal noise. Then small front chain ring and largest and next to largest rear sprockets shift into smoothly and there is no noise. Depending on how much you ride, a new chain every year saves the gears. I was riding 450 miles a week more or less, plus races so my daughter and I used a chain a month.

Why the two lowest gears......so when you start up a bad hill and you are tired you never ever start out in the lowest, always save that one for getting to the top!

I though it was spin up in an easy gear and shift down, hammer and drop them one by one until you crest the hill and run that big ring in the false flat and hammer to gain some real distance.

red-beard · red-beard's Garage

Love note from the MS Society today. Only a month until signup for the 2014 Houston-Austin MS150.

jim72911t · 09-12-2013, 08:47 PM

vash,
Bite the bullet and get a new chain and rear cassette/freewheel. I don't know what you are running right now nor do I know how old the components are, but chains and cassettes/freewheels have come a long way in the last 10-20 years. Even if your old setup isn't completely worn out, the new stuff will shift SO much better. My guess is that with a proper tune, your rear mech will work fine with these upgrades.

(it might even make you want to ride the bike more

)

John Rogers · 09-12-2013, 08:49 PM

Not me, I was a sprinter NOT a climber!

look 171 · 09-12-2013, 10:43 PM

Quote:

Originally Posted by john rogers

Not me, I was a sprinter NOT a climber!

Me too. I hate climbing. Climbing was not really necessary when there were only crits. available for us to race. I have only been dropped completely on a few races in my racing career. I was dumped like a bad habit due to the huge amounts of climbing at the district road race in Acton during my 2nd year as a Jr.

Back to our regular programming.

Vash, I re-read what you wrote. it sounds like the cable is loose. Tighten it up or change out the cable (maybe its time) and grease it before putting back into the housing.

red-beard · red-beard's Garage

If the cable is losing tension, it is time to change it.