Jim 7 speed cassette on a triple

[sam.per...@gmail.com]

Any one know if a 7 speed 42 would work with a long cage silver triple? Or is it only compatible with a wide double?

Thanks
Samuel

Sent from my iPhone

[Garth]

As long as you're within the total capacity of the RD it could work with one of those Wolf Tooth derailleur hanger extensions, called a Roadlink I think. Others make them, but Wolfies and Wheels Mfg I know for sure use a stainless steel bolt, while the other use aluminum.  The Wolfie helps to clear the largest cog only, it doesn't add any capacity, that's for the RD.  A 13-42 , at 29 teeth, doesn't leave much room for a triple with much spread. 45t is what most mtb RD are ? That leaves 16t spread for the rings. I for one never use certain combos of course so these "formulas" are theoretical, actual use, if you know what you're doing, can go beyond all that. "Know what you're doing" ... meaning .... not running say a 26t small cog and the last 3 cogs, and likewise, not using the big ring in at least the 2 largest cogs, it really depends on the crank chainline and how much you heed or ignore the horrible sound of cross angling of the chain.

A half step triple would work, like a 44/40/28 for example. The numbers are off the top of my head, not a suggestion. Having the half step would help split some of the large jumps in the cassette.

[Yankeebird]

What about a 1x?

How do I calculate wrap for that?

I have two older bikes with the old trad 7spds cassette I’d like to replace with 13-42. The Altus has a max rear cog size of 36 but if I only do a 1x does it matter? Can I use the old derailleur, even?

[Jared Wilson]

I have two bikes with Altus RDs shifting 11-42t 9 speed with derailleur extenders, but I've heard of people squeaking by without one.

[Garth]

The wrap for a 1x Yankeebird is whatever the spread is for the cassette alone, since there's no other ring there's no additional difference to account for.

As for clearing the 42t cog, the only thing that matters is that the RD can clear it alright. The "how" that is done, well there are endless creative ways to do that with endless RD's ! With extenders you would be able to use a road RD. I know back in the 70's there was a bike shop in Missoula, MT that made custom extenders and freewheel cogs using Campy racing RD's I believe. They were really loooong ! You'll be fine with most off the shelf things you can buy today.

[Yankeebird]

Thanks, all. I don’t have a lot of personal rear derailleur screwing around experience. Usually IGH or one cog with 3x up front. I got the Altus and extender in case and I’ll post back.

[Joe Mullins]

This exact setup is going on my Susie once it arrives. I will first try it with a long cage derailed and no extender and report my findings!

Joe in Los Angeles

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[Drew Saunders]

"A half step triple would work, like a 44/40/28 for example. The numbers are off the top of my head, not a suggestion. Having the half step would help split some of the large jumps in the cassette."

You guessed pretty well. The jumps in the 13-42 average about 18%, and a 44-40 is about a 9% change, so that's a near perfect half step. A 28-42 is a pretty low gear, so if anyone really wanted to live through the glory years of half-step gearing again, the 13-42 would work. I don't know why anyone would want to shift so much if they didn't have to, but you could.

[Patrick Moore]

Half-stepping actually makes sense for rolling terrain where you shift at least a couple of rear cogs at a time -- terrain with sharp elevation changes, and use the chainrings to fine tune on flatter portions. But it made more sense with few rear cogs; I worked it out once long ago and it works well with up to 5 or 6 cogs; beyond that number and you end up with too many high gears or too-small gaps at the low end. But I did "pseudo half step" a 7 speed cassette, half-stepping the middle 5 and using the big (IIRC, 4 t jump) as a bailout with inner ring only, and the small as a downhill gear with the big ring only; with 48/45 or 47/44 rings, this gave a very useful commuting setup, with the 2 most-used cruising gears in the middle 17 t cog, and "indexed" shifting between the 2 rings (IIRC, the cruising gears were roughly 70" and 65"). Front shifts are very fast and precise: just slam the lever back and forth against the stops, at least, if you don't have a granny ring (my granny was the 32 t big #7 cog).

Of course, 9+ speeds make all of this more or less academic.

[Garth]

I suppose the "guess" comes from experience in doing such gearing with a 13-15-17-20-24-28-32 freewheel and 26/44/48 rings.  What usually doesn't get expressed about half stepping is that you simply don't have to half step, or certainly not all the time !  What I'd do is simply treat it like any other triple with typical spreads(like 36/48 rings for example), and only use the half steps as a fine tuning when necessary. the efficacy of all this really comes down to knowing what gear ranges you typically ride for your local terrain. Hence, no cookie cutter formulas ! This is what I love about multiple rings and cogs, there's endless ways to configure  and shift it all.