In my search to see if it's even possible, I ran across Saint Sheldon (for the millionth time!) and a description of his Hetchins set up with 50/28 TA crank. Here's his photo:



I figured, if he can do it, I sure as heck might as well try. But as a great Jedi master once said, "Do or do not. There is no try."

Not sure if it's visible below, but that's a Sugino Super Maxy crank (TA Pro Vis copy) set up as 50/26 (go big/small or go home!). The freewheel is 6s 14-28. With the stock Suntour Mountech derailleurs, it actually works! Out of 12 possible combinations I have 11 distinct, usable gears with a 394% range! You can see that "big/big" is tight, but it works. As Sheldon stated: It's not idiot proof. I have to be very conscious about how I shift into big/big, from the 26t chainring to the 50t, and into small/small. But it doesn't take much time to get used to the quirks and the drivetrain works very well. The picture below is a beta-test of a low-rider bike-camping test run after 33 miles of mostly gravel and a number of >10% gradients with 27# of gear in the packs.

For everything up to small rolling hills, I use the 50t. When the going gets tough, the 26t gets used. But when I crest the hill, a very gentle upshift gets me back into the 50t ring without complaint, and off I go!



What else is out there?

Now that is wide.

Best I've got is 50/34, but that's pretty standard compact double. What's not standard is the 11-32 rear cog set which gets me a range of 28 to 119.9 gear inches. I love putting MTB cassettes on my road bikes

And this is shifted by TriColor derailleurs. (Yes. Totally, strenuously maxed out)

48T, 49T and 50T x 26T doubles were quite common on French touring bikes prior to the 1970's. They used long cage Huret derailleurs, usually with a maximum 13-24T or 13-26T freewheels. The later literature say 36T to 53T but Frank Berto says different in "The Dancing Chain"

The biggest problem with a gap that large is the chain dragging on the inside of the large chainring when on the small ring and outer freewheel sprockets. Long chainstays and adjusted chainline helps reduce or eliminate the problem.

26T-46T



I stopped using TA 26T chainrings after I ovalized a few over the years starting from a dead stop on a steep grade. I switched to 28T or 30T chainrings and haven't had the problem on my TA rigs anymore.

50T-46T-30T half step triple. Same problem with chainring drag but on the middle ring with a 26T. 30T fixed it.



verktyg

I have been using s 27t-47t double on a couple bikes. The cassette was 13-32, or maybe 12-32, 8 speed.

The system worked, but at it happened the most useful gears were on the large ring and I tended to avoid the overlap gears on the smaller ring because there was so little chain tension there. Occasionally the front derailleur would drop the chain completely when shifting down to climb a hill.

I have now replaced the 47t ring (the one shown above) with a 42t ring. On a similar setup I was able to find a 44t ring:

I used 26-46 on a co copy of a ta for years. They work great.

I'm running a 47/32 on my 1978 Trek TX 900 with a 12-30 7 speed freewheel. Not as super wide as the OP is talking about though!

I don't like it.The problem, with old school cranks is that the chainrings are pretty close together and that means you are trimming the FD all the damn time. No thanks, I'll take a triple over a superwide double. I started a thread on this here, Compact double or triple on C&V bike?

53/34 Wickwerks on the Tourmelet. Readily available and they shift great with my Dura Ace FD.

and a ta 26 will fit where the 30 is!

I like it in theory but not in practice. The shift pattern is annoying, and the chance of dropping the chain is significant.

I don't have much of a shift pattern, to be honest, on the bikes I have set up this way. I use the FD very much like the high/low gearing on my Jeep. Big ring (48-50T combined with a 14-28 or even bigger FW) for all normal riding, and the small ring for when the going gets tough.

Adjusting the derailleurs so there's no rubbing or - indeed - dropping the chain - just takes a little more time, IME.

High/low is a shift pattern.

The issue isn't that it's complicated, it's that the shift when you want to change ranges is pretty big and disruptive. Super-wide doubles usually need to be shifted gently, and you need to dump loads of gears in back to compensate for the ratio change.

When I do shift to the granny up front, it's usually because I just ran into a big and disruptive incline and want to be in the lowest gear as quickly as possible to avoid coming to a stand-still while I gently shift.

^^^ That's pretty much how I use it.