Front Derailleur for 48/38/28 XD2 triple, please

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531colin
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by 531colin »

mlteenie wrote: 12 May 2021, 4:41pm
Brucey wrote: 12 May 2021, 3:40pm what exactly is your chainline?
Hi Brucey
I have no idea :-) I can google how to calculate it?
https://sheldonbrown.com/chainline.html
UpWrong
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by UpWrong »

mlteenie wrote: 12 May 2021, 1:04pm
UpWrong wrote: 12 May 2021, 11:33am Spa TD-2 road triple, Sora FD, Deore shifter, widget to change the cable pull at the FD:
IMG_20210509_125123_HDR.jpg
Interesting. How does the widget affect the shifting?

My shifter basically seems to travel a bit too far in either direction after being adjusted optimal in every direction, but I'm going to have to check whether a wider b/b might help the whole problem or not...
The widget means the FD doesn't move as far for each click of the Deore Rapidfire shifter. It works by lengthening the lever where the cable pulls on the FD. It came with a recumbent bike from Kinetics. I don't know if it was original equipment or whether he added it. It's the kind of thing he might have or be prepared to make if not.
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by slowster »

According to the link below, the front derailleur was designed for 47.5mm chainline, and intended to be used with a chainset with 46/36/26 chainrings. I doubt the 2 teeth differences compared to 48/38/28 would be critical or decisive in resulting in poor shifting.

https://www.retrobike.co.uk/gallery2/v/ ... m.JPG.html

It looks like it is a 7 speed derailleur, so I presume it has a slightly wider cage than is ideal for a narrower 9 speed chain. If so, I wonder if the shifting might be better with a friction shifter (assuming that everything else is OK, i.e. height and arc of movement of the cage. In other words, if the cage is so wide that it doesn't quite push the narrower 9 speed chain far enough per click for a good shift, a friction shifter would allow that to be overcome (if necessary by slightly overshifting and then trimming the cage back to avoid rubbing on the chain).

The chainline can be changed by fitting a longer axle. If the current bottom bracket is a Shimano model, Brucey has listed the various dimensions of the different sizes in previous threads. In short, the right hand 'stickout' of a Shimano 110mm BB is 21mm, 113mm is 23.5mm, and 115mm is 24mm (i.e. they are asymmetric and the change in stickout is not directly proportional to the change in axle length). So the difference between a 110mm and 113mm corresponds to the 2.5mm difference between road triple and MTB triple chainlines (at least for Shimano BBs).
mlteenie
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by mlteenie »

https://sheldonbrown.com/chainline.html
[/quote]

Thanks. I had a vague memory of that. I will measure to clarify but in terms of middle ring to middle sprocket it looks pretty good and straight.
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by mlteenie »

Thanks Slowster and everyone else. I think it might predominantly be the cage width issue above everything else but I'm not 100% on that.

Due to the other variables such as limit screws and cable tension, It will take some deeper pondering - it can be set up in various ways and depending how it can be a problem with the middle shift or down to granny. The pushing on the lever feels like it has to travel too far, esp to the middle ring.

I'll think on it after work.
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by zenitb »

esasjl wrote: 12 May 2021, 4:52pm I think the LX f/d may be intended for 44/32/22 on an MTB chainline. Mine worked OK on 48/36/26. Maybe it is the 10-tooth difference rather than 12 that is an issue? The inner cage plate may have a groove to lift the chain a specific distance. Is it the middle to outer change that is an issue?

I've moved all my other bikes to friction shift f/ds, and 1990s Shimano CXs are both cheap and good for 48-tooth outer chainrings and any middle/inner combination you like.

PS, on checking I have an FD-580, not a 560.
Reading this thread I realised with a shock this is actually the setup I have on my 1993 Cannondale M700. It originally had and M560 front derailleur AND front chainset but after 20 years of abuse I somehow stripped the pedal threads in the Deore M560 chainset and put a Spa XD-2 like yours on instead. So the original chainset this front mech was designed for is a 46/36/24 as shown below in this Shimano pic... and I have the same size 46/36/24 rings with my Spa chainset.

Shimano M560 groupset
Shimano M560 groupset
https://www.shimano.com/en/100th/histor ... #gallery-2

Note my M560 front mech was (and still is) teamed up with a friction only Shimano Deore left thumbshifter - still a great way of changing/trimming the front mech IMO
Deore left thumbshifter
Deore left thumbshifter
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531colin
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by 531colin »

mlteenie wrote: 13 May 2021, 8:07am Thanks Slowster and everyone else. I think it might predominantly be the cage width issue above everything else but I'm not 100% on that.

Due to the other variables such as limit screws and cable tension, It will take some deeper pondering - it can be set up in various ways and depending how it can be a problem with the middle shift or down to granny. The pushing on the lever feels like it has to travel too far, esp to the middle ring.

I'll think on it after work.
I don't know off-hand the width difference between 7 and 9 speed chains, and I'm somebody else who uses exclusively friction front shifting.
However, I'm sure you could squeeze the cage in a bit, but I wouldn't do that as a first thing.
I think the really important things are
the position of the mech....ie close to the teeth, not halfway up the seat tube, and parallel to the chain in middle ring/middle sprocket.
the right number of teeth difference between middle and big ring
the right chainline
matching mech and shifters; both MTB in this case so OK I think
On friction front shift I set mine up so the mech. cage will go well in towards the frame for that essential middle to granny shift. I have a chain watcher so the chain can't overshoot and drop onto the bracket shell. You might be able to do this with indexed front shift if there is a trim click on the granny ring setting.
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Sweep
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by Sweep »

slowster wrote: 12 May 2021, 6:48pm

The chainline can be changed by fitting a longer axle. If the current bottom bracket is a Shimano model, Brucey has listed the various dimensions of the different sizes in previous threads. In short, the right hand 'stickout' of a Shimano 110mm BB is 21mm, 113mm is 23.5mm, and 115mm is 24mm (i.e. they are asymmetric and the change in stickout is not directly proportional to the change in axle length). So the difference between a 110mm and 113mm corresponds to the 2.5mm difference between road triple and MTB triple chainlines (at least for Shimano BBs).
Interesting - I didn't realise that was the case - the asymmetry - explains why I managed to fix a similar issue of mine a while ago. I fitted that XD2 to a 9 speed build based on a 90s hybrid (they have MTB genes) and initially used a 110 spindle square taper. Had trouble getting onto the small ring. Changed to a 113 square taper and all sorted.
Will try to post again with more on front mech I used later - from memory the spec sheets say it shouldn't really work but it works fine with my bodging.
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by PH »

Not wishing to confuse things and sorry for the vagueness - When I first got into cycling I bought a hybrid that the previous owner had changed the front derailleur on. I couldn't set it up right and it was driving me mad, took it to a bike shop who swapped it for one designed for the correct seat tube angle and it remained perfect till someone nicked it a couple of years later. Apparently they're designed for one of two angles, sometimes it doesn't matter, sometimes it does.
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531colin
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by 531colin »

PH wrote: 15 May 2021, 2:15pm Not wishing to confuse things and sorry for the vagueness - When I first got into cycling I bought a hybrid that the previous owner had changed the front derailleur on. I couldn't set it up right and it was driving me mad, took it to a bike shop who swapped it for one designed for the correct seat tube angle and it remained perfect till someone nicked it a couple of years later. Apparently they're designed for one of two angles, sometimes it doesn't matter, sometimes it does.
Well, yeah, MTB ones are designed for MTB chainstay angles, and road ones are designed for road chainstay angles.
The cable pull is also different, and they expect a different chainline as well.
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by PH »

531colin wrote: 15 May 2021, 6:54pm Well, yeah, MTB ones are designed for MTB chainstay angles, and road ones are designed for road chainstay angles.
No, there's various versions designed for road angles and MTB cable pull.
mlteenie
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by mlteenie »

Hello and thanks again all,

I have fiddled with limit screws, cage angle and cable tension and I now have everything working I'm sure as well as it can under the circs.

I can go from 3-2-1 easily but in the other direction 1-2 doesn't get very close to the index stops - in fact 2-3 works ok but each change requires what definitely feels like overshifting (ie. thumb has to travel a good way past index stop to reach each chainring).

It seems a friction shifter would be the simplest solution but after all this the main issue appears to be the mismatch between road and mtb components so maybe I will with slight resignation leave everything as it is rather than have two different shifters for little gain- and two different shifters would irritate me!
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Sweep
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by Sweep »

mlteenie wrote: 16 May 2021, 11:16am Hello and thanks again all,

I have fiddled with limit screws, cage angle and cable tension and I now have everything working I'm sure as well as it can under the circs.

I can go from 3-2-1 easily but in the other direction 1-2 doesn't get very close to the index stops - in fact 2-3 works ok but each change requires what definitely feels like overshifting (ie. thumb has to travel a good way past index stop to reach each chainring).

It seems a friction shifter would be the simplest solution but after all this the main issue appears to be the mismatch between road and mtb components so maybe I will with slight resignation leave everything as it is rather than have two different shifters for little gain- and two different shifters would irritate me!
Glad you basically sorted it so I won't trouble you with a front mech suggestion.
With regard to your remaining issue/niggle I'd take a look at a Shimano left 440 or 441 shifter.
Indexed rapidfires but with an extra 1 or 2 trimshifts.
I use these on all my flatbar triple builds - one 8 speed triple, the other two 9 speed.
I find them a bodger's delight.
I don't think they are made any more but they aren't hard to find in good condition on the bay.
They are pretty service free, very reliable, but if you ever do need to take them apart, make sure you use JIS screwdrivers on the little screws.
Only the OCD would mind about them not matching the right - they are pretty attractive things.
Most are silver though I do have a black one.
Edited for typo
Last edited by Sweep on 16 May 2021, 3:25pm, edited 2 times in total.
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by mlteenie »

@Sweep - thanks. I will have look into those - a trim might work.
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531colin
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Re: Front Derailleur for 48/38/28 XD2 triple, please

Post by 531colin »

mlteenie wrote: 16 May 2021, 11:16am.............
I can go from 3-2-1 easily but in the other direction 1-2 doesn't get very close to the index stops - in fact 2-3 works ok but each change requires what definitely feels like overshifting (ie. thumb has to travel a good way past index stop to reach each chainring)...............
Perhaps I'm being thick here, but going from smaller ring (or sprocket) to larger its supposed to work like that?
The shift uses the whole range of the (thumb) lever, deliberately to get an "overshift"....because without the overshift, the chain won't climb up to the bigger ring (sprocket). Then, when the shift is complete.you release the lever and the shifter ratchet drops back a bit. Isn't it?

And I think you are using an MTB front mech. with a road chainline, which won't help shifting up to bigger rings.
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