John E

https://www.ebay.com/itm/30401001294...ac21%7Ciid%3A1

My complete Capo Sieger came geared the same way -- 58-45 / 14-22. I always assumed the 58 was someone's aftermarket affectation, since all of the Capos I have seen came with 52-46 or 52-48 or 51-47. The Campag. Gran Sport front and rear derailleurs of that day would have a great deal of trouble handling a 13-tooth drop in front, even though that became routine years later with 52-39 or 53-39 and better derailleur designs.

Side note: Like my Capo Modell Campagnolo, this Legnano hase plain gauge tubing, given the 26.4mm seatpost diameter. The Siegers take 27.2mm.

Reynolds 

Could be useful for a 20" wheel bike.

Ex Pres 

I was thinking good for a 650c Tri/TT bike.

650c = 584
700c = 622

584/622 * 58t = 54.45t for the bigger-wheeled 700 frame. Now this does not include the size of the tires, so it's not quite correct, but close enough to resolve the question.

Edit: my bad ISO numbers are corrected below in post 21 - but the results are better.

randyjawa 

My Quintanna Roo has a similar geared crank set (55 x 45) as I recall. The Roo sports 650c wheels. At first I thought, no way I can push that gearing but I was wrong. The bike was not that demanding to spin...

CliffordK

Oh, I like it...

You don't really get the super low gearing, but say one has
58/45 x 13/23

58/13 = 4.46
45/23 = 1.95

Compare that to say:
50/34 x 11/28

50/11 = 4.54
34/28 = 1.21

So, the 58/13 is still lower gearing than a modern "compact".

Not necessarily the best choice for loaded hill climbing touring.

canklecat

Maybe intended for a time trial? Even on a 700c or 27" bike the larger chainring combined with larger cogs on the freewheel, starting with a 13T or 14T smallest cog, would probably run smoother and compensate for the slightly heavier bike. I noticed a lot of "chordal action" vibration in my newer bikes with 11T and 12T cogs on the cassettes -- it feels grindy and inefficient compared with a 13T cog and 52 or 53 big chainring. So switching to a compact crankset of around 50/34 seems to just trade off one problem for another.

CliffordK

I'd be all over it if it had more sensible gearing such as 58/54

oneclick 

Variation of a 13T is approx 2.75%, 11T is 3.75%.

ZudeJammer

that will be a pretty big cassette to get a 1:1 gear...hope you like walking up super steep hills

scarlson 

584 is 650b.

650c is actually 571 so it's actually 53.24t. Even more close to correct.

CliffordK

Unless one is regularly climbing very long 30% slopes, one doesn't need anything close to a 1:1 gearing.

Going back to a vintage comparison, say one compares:

52/42 x 12/21 to
58/45 x 14/23

52/12 = 4.33
42/21 = 2.0

58/14 = 4.14
45/23 = 1.95

So, in this case, the 52/12 gives slightly higher gearing, and the 45/23 gives slightly lower gearing.

So much is about the freewheel one is pulling behind.

Of course, it does give one some flexibility to throw on a 12/17 freewheel.

Andy_K 

That depends on who that "one" is. If it's me, I need it.

FWIW, Chris Froome has used a 5X-34 crankset with an 11-32 cassette on some mountain stages in grand tours. And that was before he got injured and lost his ability to climb.

John E

Yes, at 112 gear-inches, 58/14 is admittedly pretty wimpy by today's standards with 130 gear-inch highs (53/11 * 27). I personally prefer a high gear of something like 50/14 or 49/14 (96 or 94.5 gear inches).

(I generally prefer the metric system, but gear-inches work out handily, as percentages of the traditional 1970s top gear of 52/14 * 27 = 100 gear-inches.)