Replacement front derailleur: what to look for?
 

Hello there everyone!

First off, I apologize for the ambiguity that's incoming. I'm not allowed to post either links or images, so my hands are a bit tied. If you Google "Schwinn Katana", you'll see the bike in question.

I'm doing a couple upgrades and the one thing I'd like to swap out is the pressed steel front derailleur. The problem is, I'm a road bike newbie and I don't know what specs I need to look for in it.

I'm in need of a 2x7 speed unit and I like to upgrade by eBaying new takeoffs. What should I be looking for? It's a clamp style mount and the pull is from below.

Any help would be greatly appreciated. Thanks for your time!

You’ll have to measure the seat tube diameter, or check the inside of the A050 clamp to get the correct diameter.

That bike looks to have stem mounted shifters, so the left (front) would be friction.

I tend to look for older FD’s on eBay.

If you are going to keep using those shifters, older Suntour Cyclone are nice FD’s that seem to handle a wide range of chainrings.

If you plan to upgrade the shifters one day, a Shimano 105 FD-1056 is one of the best with flat chainrings and STI shifters.

John

Hi there John and thanks for your help!

I forgot to mention, I'm using the Shimano Tourney shifters, the set that combines brake and shifting levers.(side to side for shifting). Sorry for not saying that earlier. Would the 105 FD-1056 work well with that shifter?

The model's John recommended are fine. As he noted you will have to determine the seat tube diameter to purchase the correct size. Generally front derailleurs come in two types:

1) Clamp-on where the clamp is built into the derailleur. For these you must buy one with the correct diameter clamp.
2) Braze-on where the derailleur has no clamp but bolts to a separate adapter clamp. Here the derailleurs are all the same but you must purchase the proper diameter separately.

The clamp has 31.8 stamped on the clamp band so that's the size I'm looking for. I found "Shimano 105 FD-5504 9 Speed Road Bike Triple Front Derailleur 31.8mm clamp" on eBay which looks like it will fit fine. I know the chains get more narrow as the gearing increases. Would I be ok running this(listed as a 9 speed) FD with a 7 speed setup?

[EDIT] scrap that, just realized it's a 3x FD. I found a Claris FD-2400 that is designed as a 2x8 setup. It looks like I can fit the 7x chain in that cage.

I suggested the FD-1056 because the inner plate has a shifting aid to help with non-ramped/pinned chainrings. I believe this was Shimano’s attempt to bridge the downtube/STI eras. I have done a setup one on a bike with the original ST-2300 and a 1056 it shifts quite well with flat rings.

But if your chainrings are set up with shifting aids, I would think most likely if the bike came with Tourney ST-A70 STIs, you can go with a later FD, like a 5500. 105’s are Shimano’s lunch pail level. Good quality and performance in a pretty tough package.

John

Thank you. I added an alert for it on eBay. Currently I'm unable to find one in a clamping 31.8 downpull configuration. I'm sure one will pop up soon though.

The rings don't have any shift aids but I may be upgrading them in due time.

Be careful or you'll end up doubling or tripling the original price of the bike in upgrades. Spending a bunch of money on upgrades for a $1500.00 bike is one thing. Spending hundreds on a $350.00 bike is another (not worth it) kinda thing.

I expected to do well more more than triple the price of the bike(I actually bought it for $100) and that's how I've always built bikes. If I had to wait to ride a bike until I saved $1,500 of disposable income, it would be a very long time before I got to ride. On a $100 bike, all the upgrades I do are installed while I'm enjoying the bike. Unlike most people, I have no need of the benefits that a more expensive bike brings me. I currently daily ride a fatbike that I bought in pieces used on CL and eBay and I've gotten almost a decade of riding out of it. It weighs as much as a compact car but that's just more exercise. Even with all the parts and upgrades I threw at it, I'm still thousands under what most people feel a quality bike should cost. I buy the take-offs that other bike purchasers feel are subpar for their needs and they are almost always better than I need. Reduce, reuse, recycle and all that good stuff :)

I definitely don't extol the virtues of spending money on crap bikes to others but it's a method that has served my particular needs very well. If I end up with a $500 bike whose parts work well together, I will consider it a win. I'm about $350 in total on it and I've got a setup that feels very comfortable. I swapped out the bars/stem, shifters and brakes and everything else has been working great. I won't mess with the wheels but I plan to keep an eye out for a better set of cranks on the auction sites. After that, it will just be a ride and repair type of deal.

Despite it's "9-speed triple" description, that FD-5504 will shift your 7-speed chain and double crank fine. Your bike apparently has friction front shifting and that makes it almost completely agnostic to both chain width and crank chainring count as you can trim its position at will. Remember, if it will shift three chainrings it will always shift two. Just set the limit screws appropriately and have fun.

I’m not sure if they ever made the FD1056 in the 31.8 clamp size. What you can do is get the FD1056 with braze-on mount and a 31.8mm braze-on adapter.

The 31.8 1056 I used was a braze-on with a separate Shimano clamp. Shimano sold a clamp separately that could be used with their braze-on FD’s.

You don’t have to look for that particular FD. As I said previously if your chain rings have ramps/pins, just find a 7-9 speed FD in good shape. Even if they don’t, any good FD will work.

John

You can also look for an FD-6401 Ultegra.

John

Thank you very much for your help, John. I don't know if it got missed but I swapped to indexed shifters(the Tourney shift/brake combo levers). Would these work with those or do I need to look for a solution to work with the indexed shifters?

You can use the 105 1056, 5500 or the Ultegra 6401 6500 with the Tourney STI shifters. They have the same cable pull.

You just don’t want to go to pre-STI, 1050, 1055 or 6400. Some say they will work others say they won’t without some creativity.

John

Just updating this a bit for anyone googling along. I tried a not-listed Shimano Ultegra 6500(it was handy) and it just seems impossible to adjust it to where I don't get chain rub in either cross-chain condition so I'm going to pick up one of the suggested PNs in this thread and will give it another shot.

On a related note, however, I'd like to upgrade the front chainrings due to accelerated wear on the stamped steel models that are currently installed as well as the fact that I will never need a 54 tooth big ring and I'd like to make the transition between rings a little less of a struggle. I was wondering if these would work for me. I am wary because the stamped steel big ring is dished somewhat and these seem flat. I wonder if that will change the spacing between the two rings. I'm hopeful that I can move the big ring in a bit toward the center of the bike as the current big ring-big cassette cross chain is causing problems riding. I think the current chainline is pretty poor.

https://i.imgur.com/e9fc8Ril.png

Thoughts and suggestions would be most welcome, thanks for your time!

Those FSA rings might not fit your crank. Yours sort of look like 110 BCD but I can't say for sure from the photo and the FSA for sale are 130 BCD. Chainring Measurements Guide - Modern Bike

Sorry, I should have mentioned that I measured the bolt spacing to confirm that I need 130mm BCD. I don't know if my bolts will be long enough to work with two aluminum rings instead of steel but I figured I'd cross that bridge when I came to it.

In your opinion, would those rings be a suitable replacement, BCD being the same?

I ended up going with Sharktooth 38 & 48 tooth chainrings and so far, they seem to be a direct replacement and I'm glad to go down some teeth on the big ring. It resolved a lot of issues I was having with the FD height on the seat tube. The bike has an odd change in shape as it comes up and with the big ring, it was causing the FD to have to mount on the ovalized part of the tube, making it impossible to make it stay put. It will be a very long time before I need a larger ring than I have on it so it was a lossless swap.

I'm very unhappy, however, with the cross-chain performance. I know you're not supposed to ride in a cross-chain condition but this will be the first bike I've ever owned that I can't keep it from rubbing the FD when in either crossed position. I guess it's due somewhat to the short chainstay on the bike making the angle of the chain too severe to make it work. It currently rubs in full CC, rubs slightly in one rear gear away from full CC and I will sometimes hear a touch of rub when under a bit more torque in second gear from full CC. I am going to do a bit of reading before making any more changes to see if I can figure out a way to lessen the rub in those positions.

If I figure out any interesting info, I'll share it. Thank you all so much for your help!

https://i.imgur.com/PhhKsaC.png