mstateglfr 

In building up a bike, I have hit an options wall concerning front derailleur. Any advice(what this place is best at!) or suggestions would be appreciated.

FRAME- made by Fuji in 1990 for a bike touring company called Backwoods. It was based on Fuji’s Saratoga bike and is identical except instead of cable stops on the downtube(for stock barcons), my frame has downtube shifter brazeons.
Its been powdercoated and is a blank sparkly gray slate.

CRANK- Shimano FC-B124 with biopace rings from ’87. Currently it has 48-38-28 rings, and I plan to swap the smallest for a 26T ring. Old, yes, but I am a selective luddite and the crank is in solid condition.

REAR DERAILLEUR- Shimano Deore XT from 15 years ago that’s basically new. Long cage, yada yada

CASSETTE- 11-32T 9 speed.

SHIFTERS- Shimano 9 speed bar ends. Friction front and index/friction rear.


So knowing what I have already, what sort of front derailleur would mesh well with the tooth size, 22 tooth difference, and attach to a 28.6 band on seat tube?
Im looking at the following 3 right now-
Tiagra 4703 - This place has sung the praises of the Tiagra 4503, but those are long gone. Anyone know if a current Tiagra 4703 would perform the same?
Sora 3503 - anyone have experience using it with similar gearing as me?
Deore M591 - can fit up to 48t chain ring and can handle the 22T difference


It’s a front derailleur mated to friction shifting, this really isnt rocket science, but if there is a solid FD which performs better than others with the gearing ill have and is $25ish(from local or overseas), then Ill try it out.

jonc123

LHT uses the Sora 3503 with 26-36-48, I changed the 26 to a 24 still works. I have no idea what the size of the seat tube is.

IK_biker

What chainline does your crankset offer?

Doug64

I can see one problem: The post 4403 Tiagra FDs can not handle a tooth difference between the large and middle chainrings less than 11-12 teeth. The 4403 will handle down to a 10 tooth difference. The rear cage of 4503, which is an outstanding FD, is too large and interferes with the middle chainring on cranks like 46/36/24, 48/38/28, 42/32/22, etc . Middle to small chainring tooth differences does not matter if the difference is not too large.

We use the 4503 on several bikes that are running 44/32/22 cranksets, and it shifts very nicely.

Look in Shimano's Tech document site, and you may find the info there.
SHIMANO Dealer's Manual / User's Manual

I ran into this issue when changing out a crankset, on one of our bikes..

HTupolev

Yeah, I've seen this issue too. Some modern triple FDs have cages that are too deep if there's not a huge tooth difference between middle and large ring. You can usually "solve" it by raising the FD, but obviously that can potentially create chain retention issues, and depending on the derailleur in question and how much height you need to add, it might be too high for the small ring.

With a friction-shifted setup, the "safe" option is a simple straight cage, like on vintage triples. But those don't necessarily provide as snappy shifts.

mstateglfr 

Oh wow, I didnt realize that bucket of barely better than department store bolts used a Sora! Hmm, I cant be seen using such lowly components.**

Totally kidding of course. Thanks for the info, not sure why I didnt think to look at what comes stock on an LHT. Could be good to try since ill save a few coin with Sora, compared to the others.

mstateglfr 

Very good to know the difference needs to be 12 per ring. I dont think I want to swap out the middle ring too, so the 4703 is off the table.
I just looked at 4403s on ebay- shipping plus buy price is going to put it out of consideration.

mstateglfr 

Dont know for sure yet.
The crank was made for a 121.5mm spindle with 5mm offset on the drive side. I got a 127.5mm UN55 bottom bracket which is symmetrical. This will move the crank 2mm in from what it was made for. So once mounted, I think the chainline will be about 45.5mm give or take a hair. I think I did that math correctly- the asymmetrical spindle would have 65.75mm on the drive side. the new UN55 will have 63.75mm on the drive side.

IK_biker

If you believe it would 45.5 mm chainline, it is a toss-up between the Tiagra and the Deore FD.
Perhaps you could install the crankset, measure the actual chainline, and then go from there (if it's between 45 and 48 mm - go with the Deore, and if less than 45 mm - with the Tiagra).

LlamaBikes

Alpina-D Front Derailleur has worked fine for me.

cyccommute 

I wouldn't pay too much attention to Shimano's tech documents. Shimano will tell you that all kinds of things can't be done with their equipment which will work just fine in real life. Basically, they just don't know how good their equipment is. The only caveat is that the tab that holds the lower spring on the Tiagra front derailer is weak. I've broken several. I'm going to try an IRD Alpina but that's not a cheap front derailer.

As to the ranges of the Tiagra, I've got one shifting a 46/36/20 and it handles the job just fine. Last spring the same derailer performed flawlessly around Lake Erie on a 48/36/22. It's at least worth an experiment.

Since you are using friction, the world is your oyster. Any one of those would be a good choice. Don't be tempted to go upwards in the Shimano line as the finickiness factor increases exponentially with Shimano derailers as you pay more for them. The Sora and Tiagra are actually better mechanisms for wide range gearing than their more expensive brothers. Same holds for the mountain bike line. XT and XTR are beautiful to look at but they work horribly.

You might also consider Sram for the front derailer since you are using friction. The Sram X series (X5, X7, X9) triple front derailers are far and away better than any Shimano front derailer. They are stiffer, more positive and more forgiving on wide range drivetrains than Shimano's offerings. I don't have any Shimano fronts on any of my mountain bikes. The X series works with Shimano 9 speed shifters like the Deore M591 so it should work in friction mode.

But, if you want the best derailer for your Biopace rings (without lift ramps and pins), find a Suntour ARx or XC (FD3500) that is a top normal derailer...it's what Shimano should have done with RapidRise but were too stubborn to recognize the benefits. A top normal front derailer uses the cable to drag the derailer down onto the smallest ring which is usually the direction that is balky about front shifting. The spring on most derailers is rather weak and has difficulty moving the chain when the chain is under a lot of tension...which is almost always the case when you are trying to dump the chain down onto the lowest gear at the bottom, or in the middle, of a hill. The top normal design is much quicker on loaded downshifts since the cable can put more force on the derailer than the spring can.

Plus you get both levers moving in the same direction.

robow

The IRD Alpina has worked well for me with cranks that have smaller chain rings, as it's radiused for such.

Alpina-D Front Derailleur ? Interloc Racing Design / IRD

Monoborracho

I just got a new Soma Saga built with some old parts. I have an LX compact triple in front with an IRD Alpina f/d specifically for a 48 large tooth. It shifts flawlessly with my 9 speed Ultegra shifters. Sheldon said it would, and it does.

A second choice would be a Tiagra, as it is made for a wide range of Shimanos lower end bikes, which means dependable. Tiagra is good stuff.

mstateglfr 

How bout a pic or two of the Saga? Love the look and build of Soma frames.

Monoborracho

I promise one in the not too distant future. I'm still fitting it and have a borrowed seat post. Also haven't settled on tires (has 28mm on now) and fenders, and the Jannd front rack from the 520 won't fit. But soon, I promise.

Monoborracho

That is an great explanation and make some excellent points. The Ultegra 6703 front shifting on our tandem, with Shimano's tandem crank set, shifts like crap, and always has. At the moment it doesn't want to go up to the big ring, and skips right over the the middle ring while shifting down. Occasionally it throws the chain off to the outside, which is always exciting.

But that could all be different tomorrow.

Hibonite

I have an almost identical set up and use a Campy Mirage FD. Very affordable and couldn't ask for better friction shifting.

robert schlatte

I have a Sora 3503 on my 1980 Schwinn voyageur 11.8 and it works perfectly with the Sugino 46-36-26 crankset. I've never had any problem moving the chain from ring to ring. Notice in one of the photos, I did have to use the included spacer to make it fit to the 28.6mm seat tube.