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Old 01-31-12, 09:51 PM   #1
amgarcia 
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Wide Double Crankset

Ever use a wide double crankset, like a VO Polyvalent Crankset? What should I worry about? How did you like it?
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Old 02-01-12, 06:55 AM   #2
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Well, I haven't used a wide-range double, exactly, but I did convert a 22-32-42 triple to a 22-42-bash, and I love it. I ride in the 42 almost all the time, so I rarely have to shift the front, and I still have the granny ring for steep hills and long upgrades. (My legs aren't what they used to be.) IIRC, the Polyvalent is 30-46, so the gearing is a bit higher than what I have, and the gap between the rings is smaller. What to worry about? Well, obviously, you lose some top end as compared to a standard double. And you won't have as wide a gear range as compared to a triple, unless, of course, you replace the 30t ring with, say, a 26t one. (Or, you could run a wider-range cassette, but then your gearing won't be as closely spaced.) With a 16t gap between your large and small ring, you will probably have to double shift every time you switch rings, and you will have to shift the rear across more cogs than you would if the gap were smaller. None of this bothers me, but it might bother some who ride differently or have different preferences.
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Old 02-01-12, 10:48 AM   #3
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I built up a 52-36 wide double,a long time ago, the PIA is when the change
between 2 favored gear ratios is a double shift , of both levers.

Maybe if there is a mountain cassette on the back and the ranges
on the 2 rings overlap a lot that is OK, then you have redundant
ratios on the little ring , smaller cogs, and big ring, big-middle cogs.

mid 80's .. friend on a Cal Coast bike tour used his double TA. 50-30,
seems OK for him, but I was not on his bike so I cannot say from experience.
On that tour , I rode a Triple .

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Old 02-01-12, 10:51 AM   #4
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I use a 34-52 front on a down-tube shift bike, paired with a 12-22 7s freewheel. Just shifting the front @ 18 rings is a huge gap, but the DT shifters allow me to shift both the front and rear at the same time. This all works nicely with the close ratio rear.
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Old 02-01-12, 11:45 AM   #5
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I have a 46/22 on my touring bike, and it does a surprisingly good job. It gives me about 11 effective gears (with a 7 speed cassette) , which isn't great, but I've never been to picky about cadence. The low end is low enough to get me up anything, but it is to low for me to do it at a reasonable pace. Touring with a group would be somewhat awkward, as even at a high cadence, it's hard to get the bike going faster than 5 miles an hour in the low gears.
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Old 02-03-12, 12:04 AM   #6
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Besides a couple of new chainrings, what would I need to do to do this to my Cross Check? Is it as easy as swapping out the rings?
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Old 02-03-12, 07:49 AM   #7
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Besides a couple of new chainrings, what would I need to do to do this to my Cross Check? Is it as easy as swapping out the rings?
It's really not possible (for me at least) to answer this question without knowing what crankset is currently on your Cross Check. It might simply be a matter of swapping out rings, adjusting the front derailleur height, and adjusting the chain length. Or, it could be more complicated. If, for example, you're converting a triple to a wide-range double, you may need/want a new bottom bracket to adjust your chainline. Double cranksets that have only one BCD (e.g., 130mm) will be difficult to convert to a wide-range double because there are limits to the size of the small chainring you can run. IIRC, the smallest chainring one can run on a 130 BCD crank is 38t, and the smallest one can run on a 110 BCD is 34t. (Which is why compact road doubles are commonly 110 BCD with 34-50 chainrings.) The Polyvalent is a little unusual as a compact double, because it has both 110mm and 74mm BCD. It comes stock with a 30t inner ring, but you can go as low as 24t.
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Old 02-03-12, 08:36 AM   #8
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As I recall the Cross Check comes speced with a triple, but with only two rings. You should be able to just remove the crankset, remove one of the outer chainrings, replace the chainring bolts with short stack ones, and add an inner ring. The derailer works fine with a triple, or wide double, and so should the bottom bracket.
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Old 02-03-12, 09:23 AM   #9
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As I recall the Cross Check comes speced with a triple, but with only two rings. You should be able to just remove the crankset, remove one of the outer chainrings, replace the chainring bolts with short stack ones, and add an inner ring. The derailer works fine with a triple, or wide double, and so should the bottom bracket.
+1 Assuming you have the stock crankset, you should, I think, have 36t and 48t rings on 110 BCD. If the driveside crank has a set of bosses at 74 BCD, then, as fuzz2050 says, just add a 74 BCD inner ring. If you choose a 30t one, then you could probably use the existing 48t outer ring and have a 30-48 wide-range double, which is very close to the 30-46 Polyvalent. You could go with a smaller inner ring, of course, but then you'd probably want a smaller outer ring as well.
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Old 02-03-12, 10:33 AM   #10
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FWIW, you can get 33T rings in 110BCD. If your cassette has an 11T cog (can't remember what the stock one is off-hand), I can't see needing a "big" ring much over 44T either...
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