Flipping front derailleur

[Deleted member 35268]

OK, it goes something like this.

I have a road bike with a Shimano Ultegra Triple 9 speed setup.

I took my front crankset off, and replaced the outer and middle rings, they were very worn and had started to jump.

The size of the new outer ring is a little bigger than the one that came off (52 teeth as opposed to 50).

The crankset is a Sora and the shimano chainring fitted perfectly.

I shifted the derailleur slightly higher up the frame, just a few MM so as to clear the large ring teeth.

I tensioned the (brand new) gear cable as much as I could, and ensured the limiter screws were as open as possible.

Result, I can't for the life of me get the chain to go onto the new largest ring.

It is important to note I ran the same gear sizes on an Ultegra Crankset earlier in the year (that crankset is also now shot).

What to do.

 

[earlestownflya]

mister is right,it's got to be at the right angle and right height,just a little fettling is required up on the stand,you'll get it
triples are always a bit off a faff

 

[Deleted member 35268]

Did I need to align the chainrings in a certain position to assist the shifting. Darn.

 

[Deleted member 35268]

[QUOTE 3926748, member: 45"]Is the mech aligned properly? It only has to be at a very slight angle for it to affect shifting.[/QUOTE]
Should be be 100 square to the chain (looking down on the chain and derailleur, or perhaps there should be a slight angle?
I have it square / level to the chain at present.

 

[earlestownflya]

Should be be 100 square to the chain (looking down on the chain and derailleur, or perhaps there should be a slight angle?
I have it square / level to the chain at present.

i usually find on most mechs that the tail end is slightly angled towards the bike.
looking a my mech now,chain on the big ring the bottom outside edge of the mech is about 6mm above the teeth,but its a double,a triple is a more complicated mech due to the 3 chain heights,just keep at it

 

[Nigelnaturist]

A triple is no more complex than a double, as you set the initial tension and low stop screw on the small ring, once the cable is tensioned and the slack taken out by the adjuster barrel providing the hi-stop is off enough, the FD will move across all three rings in turn. So you are only adjusting for outer and inner rings, the same as you would a double.
I am not sure what fitting you have on the BB, but some chainsets require different length BB, I have three chainsets each requiring a different length BB 110mm (I think it was) 113mm my current and on of 116mm (though I used a 115 on that) this is on a square taper, if its too short it will struggle to move out to the outer ring.

 

[Tim Hall]

Wot nigel said. Have it dead straight and the thickness of a 2p piece above the big ring.

 

[Deleted member 35268]

I have to sort this tonight, as I broke my spare bike today also

N+1 imminent.

 

[earlestownflya]

a triple is more complex than a double,it's a completely different shape and a more complicated design,it has to be so for the 3 chain heights so that it can run without catching the chain and still shift properly..it might not even work with your new ring combination,because the shape of the mech was not designed for your new chain height.the best thing to do would be return it to 50 teeth .

 

[Nigelnaturist]

a triple is more complex than a double,it's a completely different shape and a more complicated design,it has to be so for the 3 chain heights so that it can run without catching the chain and still shift properly..it might not even work with your new ring combination,because the shape of the mech was not designed for your new chain height.the best thing to do would be return it to 50 teeth .

Poppy cock, my 105 FD is designed for 50th max according to the docs and a max tooth difference of 22th go figure if you start at 30th, I have run it with upto 24th differance on both 52/40/30 and 50/38/26, yes it has to cope with three rings but setting it up is no more difficult, trust me I have done it loads of times.

 

[earlestownflya]

Poppy cock, my 105 FD is designed for 50th max according to the docs and a max tooth difference of 22th go figure if you start at 30th, I have run it with upto 24th differance on both 52/40/30 and 50/38/26, yes it has to cope with three rings but setting it up is no more difficult, trust me I have done it loads of times.

strange the chap can't do it then,seems to know what he is on about....there's" it'll do" working and "sweet as a nut" working..which one do you go for?...never touch shimano anyway ,never had any dura-ace running gear,so can't comment on that, but the rest is rough as f*ck

 

[Nigelnaturist]

strange the chap can't do it then,seems to know what he is on about....there's" it'll do" working and "sweet as a nut" working..which one do you go for?...never touch shimano anyway ,never had any dura-ace running gear,so can't comment on that, but the rest is rough as f*ck

My front is actually better than my rear, but that more to do with the jockey wheel being to far from the cassette, and yea sweet as a nut springs to mind, even changing up a ring up hill out of the saddle, though not something I do to often.

 

[Deleted member 35268]

Ooooh, so close. Spent another hour on it last night, cable tension adjusted, limiters adjusted, same thing. Then, I started a fresh this morning and bingo, got it to to go from middle to biggest cog smoothly. But alas, it won't drop back down to the smallest. I think I am within a few tweaks of having this sorted. I think the larger chain ring I bought is naff - it does not have any of the "hooks" (if you know what I mean) on the inside that help with shifting - there are none - its a 52 tooth shimano Ultegra ring. I think the issue is I bought the wrong chain ring, well, the largest one anyway.

I currently have no ride-able rides (apart from an old MTB) as I broke my spare bike yesterday too. With all this fine weather, I am really fed up - but it is meant to be.

 

[earlestownflya]

you might need to add a couple of links to your chain to account for the larger ring(if you still have some knocking around).

 

[Nigelnaturist]

@Rooster1 Whilst shimano FD are helped by the ramps they are not necessary, rode a 30/38/50 with cheap dural rings on a Sora FD and it worked. @earlestownflya this should only really be necessary if riding on the rear larger cogs it shouldn't stop it moving to the large front if on the higher end of the cassette i.e. smaller cogs, but yes to be correct you are right.
@Rooster1 to determine chain length, wrap the chain round both large rings front and rear, without going through the RD you should have 1-2 links over lap.