Triple a corncob?
 

My typical ride route is the local rails to trails bike path, I have a decent climb at either end of my route. Only a few hundred feet of elevation, but steep. Particularly at one end of the ride, I must get into the bottom gear and out of the saddle or I'll be walking. The gearing is 42-24 on my 83 Schwinn super sport. I need a way to spin up these hills.

What is the wisdom of a triple on a close ratio cogset? During the flat portions of the trail I'm wishing for closer ratio's.

I have suntour ARX on the bike. Would I need to replace both the Front and Rear derailleur?

Alternatively, could I assemble a freewheel with a closer ratio set on the first 5 (or 6), and then a bailout? What is the capacity of the RD? What is the biggest jump the RD will handle?

Thanks,

Gary

Gary, I can't answer the more pointed questions, but a triple mated with a close ratio set of rear cogs works well for me. :)

Brad

The last two long charity rides I've done has been on bikes with 12/13-24 rear clusters couples with a triple up front. One bike was pretty much good to go from the start; the other required a bit of care in shifting, and I used the small front cog only as a bail-out.

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The Suntour ARX is a pretty burly derailleur- I think any sort of bigger jump on a close range cogset is probably more limited to the length of the chain.

Bernard Hinault was a fan of them. He figured he could climb a wall with a corn cob and a campy triple (52-42-36). What the heck, if it was good enough for him, it's probably OK for an ordinary mortal, right?

Capacity on the RD can be found here: SunTour aRX derailleur (4300)

I'd try out the FD with a triple; it could well work.

Best triple for a vintage bike is probably the sugino xd600. It looks good and is reasonably priced. Plus the 46-36-26 chainrings give you great climbing gears with a 13-24 freewheel.

Wouldn't there be a huge gear-inch gap when downshifting between the lowest gear on the middle ring to the granny? Like 40 to 29?

analysing my riding behavior, I'd really like to have one of those. I think a 50+ chainring makes little sense to us mortals, and a 39 won't get me everywhere I want to go, especially later in rides. My favorite combo for general riding so far has been a 42 inner ring with a 13-18 corncob (5 speed), so for my next build, I'd like to make a 44/34 bike with one of those 13-21 7s/13-23 8s cassettes. No triple, as I don't really care for the high thread and fussy shifting.

I'm running a 50-36 (just took off the inner triple ring) and 13-21 on my Trek 510 and like the combination a lot. Can climb most anything around here reasonably well and also handle the heavy headwinds nicely.

Triples are mostly useless in my opinion. I think the reason they were invented is because while everyone understood that non-racers needed rings smaller than 38 on a road bike, they didn't understand that few people need anything larger than a 50. That is why 110 bcd compacts are so ideal for road riding - no need for large capacity rears, etc. Any interest in just finding a good compact crank - only drawback is you might not look as vintage unless you go with something like a Grand Cru 110?

Triple and a corn cob is awesome! You still have the standard rings and close ratios for the flats and the granny when you need to climb something. I run 52/42/30 or 52/40/30 on all of my bikes. Out back is something like 13/14-19/21. If it is a climbing day then a freewheel/cassette with a 24/28 goes on. Hard to believe, but I spend more time on the 52 and the 30 than I do the middle ring.

I must be missing something here:

If you want a corncob (i.e, with close gear ratios) why then would you defeat it with huge tripleized jumps? Seems a contradition to me... Why not just install a FW with a 28T low gear instead?

I like it on my Passage. I recently switched it from the original 15 speed half-step setup to 21 speed "three range" as I call it. 50-38-26 with a 13-24 or 12-21 freewheel. Much better setup IMO. Most riding goes just like a double with the majority of time spend in the middle ring and long smooth flats and downhills in the big ring but I've got that inner ring for climbing a muddy/sandy hill when I get tired (this bike mainly sees unpaved backroads). So far, I've only used the inner ring as a bailout but it does have some gear range overlap with the middle if I go 4 or more cogs smaller in back. Honestly, a close ratio cogset makes more sense with a triple - why have all those gears only to have most of them overlap?

Not quite a corncob, but I'm running a 13-24 6s freewheel with a 52-44-28 front. Cyclone MkII w/GT rear. It all works swimmingly, and the low gear is about 31 gear inches, much better than a 42x24 ~ 46gi. For most of the riding I end up in the 44t front. The 28 gets used primarily with the two largest cogs only.

Wide range, with relatively-close spacing between each individual gear -- best of both worlds. Drew Eckhardt really likes this configuration, so I'll be surprised if he doesn't chime in here. ;)

The major component companies are trying to accomplish this with 10- and 11-speed cassettes and 50/34 compact cranksets, but there is something to be said for needing less corrective shifting in the rear after a front shift.

When I start needing gears lower than ~40" on a regular basis again, I'll probably take my triples out of cold storage and set them up with 13-14-15-17-19-21-23T "I" cassettes, or 13-14-15-16-17-19-21T "J" cassettes if I can get my hands on more. And anyone who complains about triples being fussy or not shifting well either hasn't used one that was set up properly or lacks finesse. :)

(Oh, and to answer that last question: it's very possible that you'll need a long-cage rear derailleur to handle the extra chain. My 48-38-28 triple with a 13-23T cassette would need an RD with a capacity of 30 teeth, for example.)

My 3x8 divetrain uses multiple cassettes depending on the steepness of the ride. I'll use a 12-21 at home where it's pancake flat, a 13-26 for general riding and a 12-28 for hilly century rides. The bike has a 52,42 & 30 chainring set. Far better than any double, including a 48 & 34 compact double.


http://i289.photobucket.com/albums/l...ps012b14aa.jpg

I also use a 48, 36 & 26 chainring set with a 13-24 seven speed freewheel on this bike;

http://i289.photobucket.com/albums/l...pse1d95ae4.jpg

Rather than a corncob, which I interpret to mean a freehub/wheel with mostly 1-tooth progressions, I like to use a 2-tooth progression with a half-step or 1.5-step up front. I was quite happy with the 48-45-34/13-15-17-19-21-23 (24 would have been even better) close-ratio half-step-plus-granny I ran on my PKN-10. It gave me tight coverage over a 40-to-100 gear-inch range with a short cage SunTour Cyclone II rear derailleur.

48-36-26 and 12/21 or 13/23 7sp works for me. Never had shifting problems with the triple.

My freewheel is 13 15 17 19 21 24 or something close to that. If I'm riding solo, it is fine. But if I'm riding with others at a more spirited pace , I'm looking for single tooth spacing, (or stronger legs) . A triple could give wide overall range and close ratios.

[MENTION=47570]Barrettscv[/MENTION] - Your drivetrains are a thing of beauty. I had my Lambert set up with the exact same components as your Serotta for awhile, only with 7 cogs in back instead of 8. The only problem was, I stopped riding all of my other bikes!

Basically using a triple isn't much different than using a double, other than a compact. There's just another chain ring for an additional set of low gears.

My distance roadie is equipped with a 52-42-30 crank set and a 14-15-16-17-18-19-21-23-25 9S cassette. Where I normally ride my most adjustments are made for the wind and the 30T is used only on some county roads west of me that have some short, but steep descents and climbs. For really hilly areas I can always throw on a wider range cassette for a deeper low and a higher top, but so far, so good with the 14-25. :)

I wasn't interested in a triple until a knee injury reared it's ugly head, but have since come to enjoy the versatility that's available. There is a weight penalty using a triple crank set with the extra material on the crank's spider, chain ring and fixing bolts and a longer cage RD.

Brad

http://bikeforums.net/attachment.php...hmentid=414338

Some gear conversations remind me of my sweetie asking about dinner "Will this be enough?" Well, ah, it depends on what else we're having, doesn't it? And how hungry we are, no? Without the rest of the specs one can't possibly say whether a 42T or a 24T chainring is good, bad, or indifferent. a 24T ring with a 14-15-16-17-18 -20 FW is a very different beast from a 24T ring with a 11-11-12-12-13-13 FW. :D

FWIW, I have a 39T small ring on my Centurion, but it's paired to a 32T big cog and 172.5mm crank arms. The Masi has a Campy 42T small ring paired to a 34T big cog and 170mm cranks. Some of my other bikes match a 34T ring to a 28T cog with 170mm cranks. They all do just fine, so I wouldn't necessarily say a 39T or a 42T won't do. I even use the Centurion's 53T big ring occasionally though I don't really need one that big.

So what else are we having?

I think it's hard to do that without introducing large jumps.
Here's what I've done on an mtb conversion. It's a much wider range even that what I ever needed, and I'm not burly enough for any more top end than that. In between, it's a nice progression with small jumps.
http://i1182.photobucket.com/albums/...ps50724f89.jpg

Keeping the rear steps close with the added range of a triple makes for a wonderful set up... you may not need the granny much but it is there when you need it.

My Ron Cooper runs a 12-26 with a 30/42/52 triple... it works really well on long steep climbs.

The problem with this setup (close ratios in back, wide ratios in front) is that when you shift in front, you have to cross two or three gears in the back, all to achieve (effectively) one shift. If that doesn't bother you, then great.

I use a 22-32-36 triple and 9 speed 12/13-23/25 and I only ride pretty flat terrain.
MOST my riding is on the middle ring.
Sometimes, I can run into SEVERE head winds, where shifting down to the granny still gives me close steps.
I rarely use the large. Basically a couple times a year when I've got a strong tail wind.

The reason I use these close gears is because of my emphysema.
I do far better riding a very narrow cadence of 80-85. My bad knees won't let me spin faster (165mm arms)
My lungs won't let me push harder.