This derailleur adjusting lark.......I give up !!

JimmyK

Tonight I set about trying to sort the headache Ive been having in that a shift from 34 inner ring to 50 outer ring is causing the chain to fall off far too frequently. I read in lots of sources about adjusting the H screw so as there is a 2mm gap between the outside edge of chain and derailleur cage........sounds easy.

Well , I turned the H screw until it was as in as tight as it would go and as loose as it would go , and it didnt look to me as if the cage had moved one jot. At the end of it all, my limit screws are both set wrong and now my bike wont change gears properly and the damned thing is off to LBS AGAIN !!!! :evil: first thing in the morning.

Im getting so sick waiting for the chain to fall off about 30% of every time i shift from inner front to outer front ring that i am not enjoying my biking at all. Surely it cant be this hard to get a chain to bloody stay on !!

Jimmy

GavH

Jimmy take some pics and either post them here or else pm me and I'll give you my email address and I'll have a look.

I know what you mean about not enjoying it, I was the same when my front mech was bent and I didn't realise; every shift just waiting for the chain to come off.

JimmyK

The bike is going back to shop in the morning gav, but i thank you warmly for your offer of assistance mate. you sound like you understand what im going through, the changing gear scenario and just waiting for the clatter as the chain falls off , sometimes its ok and sometimes it drops straight off. Takes 75% out of the joy of cycling straight away :roll:

The ole chain dropping certainly seems more frequent after i had the compact fitted, wonder if that has any relevance. Wonder if having a 9 speed chain fitted would make a difference, my 12/25 rear is an 8 speed but its a compact at the front.

salsarider79

If you changed from a set of 53/39 to the 50/34 set up, the front mech may not have been adjusted correctly. Especially if you changed the whole chainset rather than just the rings.
The limit screws will only limit how far the front mech can travel. So if you weren't turning the pedals (You really need a workstand for this) and changing gear, the limit screws won't do much (except pi$$ you off).
It sounds like cable tension is what you need to adjust, and possibly also front mech height. Hope it all goes okay tomorrow....

amaferanga

If you were turning the H limit screw when the mech was on the big ring then it should have moved when you were screwing it in. Sounds like you were turning the wrong screw to me.

I think you're making this more complicated than it really is. Get someone at the bike shop to show you how to set-up the derailleur.

softlad

if you are running a 9sp chain on an 8sp set up, then you will need to reduce the throw of the derailleur on both the inner and outer rings - because the 9sp chain is narrower and the mech will effectively be overshifting it, causing it to fall off one end or the other.

I fitted a 9sp chain to my 8sp winter set up - but 30 seconds messing about with the limit screws sorted it.

JimmyK

softlad wrote:

if you are running a 9sp chain on an 8sp set up, then you will need to reduce the throw of the derailleur on both the inner and outer rings - because the 9sp chain is narrower and the mech will effectively be overshifting it, causing it to fall off one end or the other.

I fitted a 9sp chain to my 8sp winter set up - but 30 seconds messing about with the limit screws sorted it.

its an 8 speed chain softlad. im just flummoxed as to how a bike can throw the chain, get it tweaked, throw the chain etc etc, i dont know of anybody else putting up with this keek that im currently putting up with, and when i turned the H screw, i didnt see any movement in the cage :shock: , its a shimano 2203 derailleur and im sure the H screw is the top one.

out of curiousity, what exactly is "winter set up " ?

amaferanga

If the screw you turned didn't do anything then try the other one? :?

John.T

The H screw only limits the amount that the cage can move outwards when you operate the shifter. You need to push the shifter when you adjust it to see how far the cage will go. The gap between the chain and cage should be 0.5 to 1mm with no hand on the shifter. this is set on the cable tensioner. When you operate the shifter this gap should be about 0.5mm more. You adjust this with the H screw. If the cage moves too far you will throw the chain over the ring.

markos1963

Its quite a common problem and you shouldn't get too stressed about it. I learned the hard way like you and I will be spending the next few days polishing the scratches out of my RH crank arm.
The solution I found is this. Disconnect the gear cable, then lower the mech until its only1-2mm max clearance from the big ring. Then if you've lowered it square to what it was then turn the leading end of the mech a degree or two inwards. Screw your barrel/cable adjusters all the way in and then uncrew them 1 turn. Reconnect the cable and then test it out by riding( take a screwdriver with you to make adjustments as you go) up and down your road. You wil probably need to reset the limit adjusters and reset the tension in the cable. I made sure the H screw was set too far in so I couldn't get the chain up on the big ring and then slowly(1/2 turn at a time) worked it out until it shifted. If you do the adjustments as you ride you find it more accurate as putting pressure on the driverain gives a different outcome compared to a workstand.
Hope this helps.