Problem adjusting front derailleur after changing crankset

fredmart

I've just changed my crankset from a Truvativ Fived 44-32-22T to a Shimano Deore 48-36-26 and can't seem to adjust the front derailleur so that it reaches both the largest and smallest chainwheels.

I've currently got both high and low limit stops fully loosened and the derailleur works fine for the top and middle chainwheels, but won't shift to the lowest one even if on the biggest rear sprocket. Changing the angle of the derailleur means I can get onto the lowest chainwheel, but then can't get onto the largest one. Adjusting the tension doesn't seem to do much either.

When I originally installed the crankset, the derailleur wouldn't go anywhere near the outer ring and I ended up moving all the spacers from the right of the bottom bracket to the left side. Aftrer doing this I realised the inside of the parallelogram was hitting the middle ring when shifting up, so I raised that, but still needed to fully loosen the high stop to get the chain on the top ring without rubbing. I currently have a shimano fd-m510 derailleur, which has specs which seem compatible with the larger chainwheels

Am I missing something? Do I need a new derailleur? My bike has taken a bit of a beating recently, and I replaced the snapped rear derailleur hanger at the same time. Could this have affected anything?

Or have I tinkered around too much and should just start again from scratch? Its seems bizarre that the whole crankset has to be on wonky, but moving even one of the spacers back over means I just can't get the chain onto the top chainwheel.

Any help really appreciated!

Fred

jimexbox

Make sure you are using the correct spacers for the bottom bracket for your bike, and make doubly sure the new crank is pushed fully through the bottom bracket. When I changed mine it looked fine but couldn't get the front dérailleur right. I stupidly didn't make sure the crank was fully through, hand pushing wasn't enough. I had to use a rubber mallet.

nicklouse

more info needed.

which fived crankset? fitting and axle length.

which Deore crankset? fitting and axle length ( or spacer combo)

and what frame?

redvee

You might have to move the front mech up the seat tube slightly. It should sit 2mm above the outer chainring.

fredmart

Thanks for all the replies and sorry for the delay getting back to you - problems logging in to the website that have only just been fixed.

Jimexbox - orginally set it up as per instructions for a 68mm BB shell. I only handpushed it in admittedly, will try a mallet

Nicklouse - GT Avalanche 1.0 2008, original crankset is a Fived 5d 68mm AL-7076-T4 (I think, don't have the original with me at the moment and again I think 170mm cranks, can check tonight if its important) on a 68mm powerspline BB. New cranks Deore Chainset M590 - 170mm 4-Bolt 26.36.48. Originally used spacers as per instructions - total of 5mm on right and 2.5mm on left. Currently have all 7.5mm on left and nothing on right.

Redvee - have already moved up the derailleur so that the inside of the parallelogram clears the middle ring when you shift into top gear. This does mean that the outside of the derailleurs is quite far above the large chainwheel, more than the 1-2mm I'd normally have it at.

Basically the thing I don't understand is that with both limit stop screws totally loose so that they're practically falling out, I can still only just get the chain onto one outer ring without rubbing but then not at all on the other. When shifted into the lowest gear, the derailleur looks like its as pressed against the seat tube as it can possibly be - not surprising as I've taken out all the BB spacers. But if I put the spacers back in, how am I going to get the derailleur anywhere near the large chainwheel seeing as it only just clears it now?

Cheers,

Fred

The Rookie

The front mech cage has steps on so that as it goes up or down the rings it moves from one step to the next to give the 'push' when needed and remove rubs when not, on one of my front mechs I had to throw out the 2mm rule book and set the height of the mech so that the chain moved from one step to the next as it went up the rings, would be worth looking at that. Alternatively if you are already a long way from the 2mm, start with that as it may sort you out by aligning the steps correctly in an easier manner.

Simon

anjs

yes a little tap with a hammer might well help

jimexbox

fredmart wrote:

will try a mallet

Make sure its a rubber one, or use normal hammer and a block of soft wood as your target.