I'm in the market for a new front derailer for the '88 GT I use for both touring and commuting. I've been running an unorthodox 53-42-32 with an 11-32. This works well for me during my commute in hilly Seattle and has been okay for my short bike camping trips so far but I suspect I"ll need more low end for some upcoming tours. I'm willing to drop my 53 down a few gears, bit not too many.

What derailer can handle the largest spread? I'm thinking something like 51-44-26, but the lower I can go while retaining the upper end would be best.

I use a vintage Suntour high normal front derailleur with my 52/42/24 and 11/32 (11/12/14/16/18/21/16/32) eight speed cassette.

I can't use the 24t chainring on the front while using the 11 or 12 cogs on the rear because the rear derailleur cage won't take up that much slack. But, those two gears are pretty cross chained so I do not use those gears. I also do not use the 52t front with the 26 or 32 because of cross chaining, but I made sure that I had enough chain so that if I accidentally shifted onto that, I would not bind anything up.

In other words, the rear and not the front is derailleur is the limiting factor.



I think a 51 and 44 would be a huge error. My 52 and 42 are one and a half step gearing, meaning that a shift on the front is one and a half times larger than a shift of one cog on the rear. I have bought but have not yet installed a 46t to use instead of the 52t, that would be half step gearing so that a shift on the front is half as much as a shift of one cog on the rear. I plan to continue using one and a half step gearing around town but half step when loaded touring.

The advantage of half step or one and a half step gearing is that you can do fine tuning of your gearing. I frequently find that I am shifting down on one derailleur and up on the other for a very minor change in gearing for a minor change in windage or grade.

I think if you calculate gear inches for the 44t and 51t gears on your 11/32 cassette, you will find that almost every gear on 44t chainring has a duplicate gear with the 51t ring. The advantage of a 24 or 27 speed system is that you get a lot of gears but your plan for a 44t and 51t would give you several redundant gears, negating some of the advantages of a lot of gears.

The upshift from the 24t to the 42t is not a smooth shift, but it works. I do not know if you have a friction shifter for the front, you will probably need one.

Most triple derailleurs are spec'd for a 22-tooth spread, most doubles a 16-tooth spread. Honestly, for a touring bike I think you'd be fine with a 26/38/48 trekking crank. If you're spinning out of the 48-11 combo (41mph @ 120rpm), it's time to relax and coast IMHO...

Okay, thanks! I'm still trying to wrap my head around how the gearing works.

Currently both my shifters are indexed, but I have a decent Sun Tour friction front shifter in the parts bin.

I'm finding it difficult to research what would be compatible with my set up (indexed 9 speed mountain, 1" steel tubing) but so far have come across the FD-R453 which appears to be spec'd at 24 tooth spread.

I'm thinking you are right about the 48, I didn't realize I was going quite that fast, I had noticed that no cars were catching up to me on one of my descents during my commute!

So, what about 48-36-24 ? Does that make sense?

Thanks again!

It's not that odd 53,42 32 is a reasonable range small wheel like the 406 , 20"
Bike Friday uses lots of them

Touring range , granny gear is roughly half the big one. middle is 10~12 teeth
smaller than the big ring.

10 and 16t differences, are a pretty classic alpine touring chainring spread

50,40,24, as an example..

Are you sure? The tech doc I found seems to suggest "20 teeth or less" as the maximum difference.

Shimano's specs do tend to be conservative, so it's possible that any of their front derailleurs might be able to handle a 24-tooth difference. Worst case, the chain will tend to fall off the inner ring and you'll need a Deda Dog Fang or another chain guide to keep in in place. That's not necessarily the end of the world...

I'm not aware of any crank that comes pre-configured as a 48-36-24, which means that you'll end up buying some chain rings. Make sure you can find the rings you need in a pattern that's compatible with whatever crank you intend to bolt them to.

If it were me, I'd probably just stick with a 26/38/48 or the 22/32/44 found on most mountain bikes depending on how much weight I was planning to carry and how far uphill it needed to move.

my winter bike has a 48,36.22 combo..
touring bike, 50,38,24,
road triple: 50,40,24, 52/24 , or 52,42,26

all work fine.. in common.. friction Bar end shifters

I've used an old Campy NR front derailer for a 48-22 compact double--with a friction shifter it downshifted impeccably, getting back up took a bit of doing though. Front derailers are really easy to overthink.

So it sounds like if I just switch to friction shifting for the front derailer and have one that approximates the arc of the chain rings it should work regardless of the spread?

My old derailer is toast - it just got munched when I was doing a little trail riding and a broken chain forced it into the chainrings so I need to get a new one either way...

Are these sold in sets that are cheaper than buying individual chainrings or something? I've already got a crank, I was just planning on changing out the chainrings...

i've done 52-28 with a road triple FD and 48-24 with shimano mtn triple derailleurs with nothing more than occasionally choppy shifting.

Quad:

https://mgagnon.net/velo/pedalier4.en.php

I used to have one like this, or something similar. Worked great, though there aren`t that many situations where I needed it, but it might work for someone who wanted more top end also.

Yes, it's called a "crankset" You can often buy an entire crankset for less than it would cost to buy three individual, good-quality chain rings. Especially true if you want 22-32-44 gearing; MTB cranks can be very cheap, provided you're not terribly concerned about weight.

Strange, but true.

My daily ride has 24- something- 48 with an old Exage mtb derailler and friction shifter. As above, it shifts down beautifully, upshifts "close enough".

Actually this is just the kind of thing that I love. I had heard of quads but assumed they weren't manufactured anymore. I think I'd really like to go there eventually, at the moment I'm afraid to start messing around with it when my commuter is down and the bike I picked up as a back-up isn't built up for me to be able to ride it. I'm steedless and bummed to have to go back to riding the bus for more than a week as parts won't come in before I have to work my 7 nights in a row at the hospital and can't get anything done during that time. I'm afraid a quad is going to either take some extra fiddling or maybe not be compatible with my geometry (nothings ever simple!). As soon as I get the back-up bike set up (this winter) I am going to see if the quad will work for the GT! That would be awesome! I do really like going so fast, even if I am breaking the speed limit!

Haha! I never considered buying a crankset, it seemed wasteful and assumed cranks were expensive. I don't really care about weight, my bike is festooned with accessories and I haven't gotten around to buying lighter-weight components for the few things I can lighten up on. Also, my back-up bike could use new cranks so it actually wouldn't be wasteful anyway. Thanks for the idea! I woulda just bought three individual chain rings!

Shopping around I am seeing some very good deals for cranksets in the 48-38-28 range but some of them say "square taper", some are designated "splined", and some as just "square". In the past when I had packed bearings in my BB or changed to a wider spindle I seem to recall them as just being square shafts. Recently though a LBS put in a new sealed unit so I didn't get a good looks at it. I assume it is just "square", is it going to be obvious to me which kind of spindle I have when I remove the cranks?

Thanks for all the help everyone! I think the guidance is keeping me from me from feeling hopeless about being steedless and struggling to figure out how to go about rectifying it.

"Square" and "square taper" are the same thing. Once you remove the cranks, it should be obvious whether you have a square taper BB. If you have a splined BB, you'll probably need to pull the BB cartridge and read the part number off the cartridge to determine exactly which spline pattern is used (Octalink V1, Octalink V2, ISIS, etc).

You can probably see if it is square taper without pulling the crank off of the bottom bracket, you should be able to look at the crank arm where the arm meets the shaft to see if there are four flats on the shaft.

We run 52-39-26 on our tandem. Works well with our Shimano brifters. We installed a chain stop because that's kind of a big drop. We ride mostly in the big ring because the little 39 ring is kind of annoying, but a 42-26 drop is too large. So it's a standard road triple crankset with a Salso 26 ring replacing the stock 30. Very inexpensive to change that ring. We do use the 39 with the larger cogs and make good use of the 26 on pass climbs.

I run a 46-34-20 with an 1978 105 derailer,works fine.

The 53-42-32 is an OEM Standard, Road triple.. factories get a pallet of cases of them for pretty cheap.
in addition Those now called 'Trekking' is what MTBs were . 48-38-28,
and compact Mountain, 44-32-22.. with 11t cassettes, 44:11 is plenty high.

I started a thread about a week ago on the topic of front crank gears you may find useful.

https://www.bikeforums.net/showthread.php/760385-Granny-isn-t-everything!

We didn’t talk too much about derailleur ranges but the gearing was kicked around a lot. My theory may help you also as you mentioned in your opening post you are looking for "commuting and touring" setup. That also being what I wanted lead me to want my front center gear to be taller than what the mtn bike triple crank set I installed gave me. I had a 44-32-22 triple on it and hated it because half the time when commuting I wanted to be on the big ring half on the middle. If I only were to use the bike as a loaded tour bike I may have liked the setup better.

Quick update: going through my parts bins unearthed the following derailleurs and shifters that might work:

- Sun Tour Compe V
- Shimano 8 speed M-566

Both are bottom pull (at least I think the M-566 is, the Compe V definitely is), for the moment I'd like to try the M-566 in the hopes that it'd work without changing the shifter, grip, and coming up with a separate (non-integrated) brake lever. If I am moving down to a 48-38-28 crankset I imagine the M-566 will work fine with this smaller spread and smaller arc than the 53.

My question on the M-566 is: I'm wondering if anyone happens to know if the M-566 will work with 9 speed indexed? Although it is supposedly 8 speed specific, as a front derailleur I can't imagine this matters.

I have the down-tube shifter from the old Gitane that the Compe V was set up with, but I also have Sun Tour Accushift and Power Shift handle-bar shifters. Any reason either of the latter wouldn't work with the Compe V ? Regarding the Power Shift, IIRC it has both indexed and friction modes, as I used it in the past as a friction shifter.

One more question, I think I am going to have to cannabalize some parts off of the GT and try and get my NOS '91 Sekai Mountaineer* running so I can commute to work this week. Are chainrings specific to a particular chain? I'm thinking I'll pull the GT's crankset and put it on the Sekai, since it already has friction front shifter, has really crappy cranks and I'm replacing the GT's crankset anyway. The thing is, the Sekai has SIS 7 speed and I'm running a 9 speed on the GT. Will the chain that is on the 7 speed work with the chain-rings I've been using on the GT's 9 speed set-up?


Thanks again everyone!

* https://www.bikeforums.net/showthread...ai+mountaineer