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Old 01-07-12, 05:01 PM   #1
jebensch 
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122 BCD - are there granny rings out there?

I'm going to rebuild my Peugeot grocery-getter to serve as my toddler-whisk-a-rounder. It's currently built as a single speed with Stronglight 93 crank that I'd love to keep on there, but I want to have a granny gear on this thing.

Is there such thing as a 26-ish tooth ring in a french 122 BCD? I suspect there isn't, and it will save me the headache to use a Campy or Japanese double if I want the granny.
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Old 01-07-12, 05:36 PM   #2
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I have a 38t and I think that is about as small as you can go with 122.
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Old 01-07-12, 05:53 PM   #3
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I have a 38t and I think that is about as small as you can go with 122.
Same here - Verktyg was selling a few last year. It's actually been a nice combination with the 52-38.
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Old 01-07-12, 09:27 PM   #4
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Yep, 38T is the smallest for that crankset, and it can be made into a triple or double with the appropriate bolts. With an appropriate freewheel, you can get pretty low gearing with a 38T front ring.
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Old 01-07-12, 11:33 PM   #5
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Yep, 38T is the smallest for that crankset, and it can be made into a triple or double with the appropriate bolts. With an appropriate freewheel, you can get pretty low gearing with a 38T front ring.
Actually 37T was the smallest ring made for 122mm BCD, but they're even harder to find than Campy's 41T 144mm BCD rings.

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Old 01-08-12, 04:31 AM   #6
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If you want to go with a granny ring on a C&V Stronglight crank, look into the model 99. When I hear "granny ring" I think of a triple ring crank. not just a sub-42 inner ring on a double. The 99 will take a true granny ring. You just can't do it on a 93.
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Old 01-08-12, 10:51 AM   #7
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Quick calculation reveals that the pitch diameter of 26T is approximately 105mm. You probably need about 12.5mm between the pitch dia and the bolt circle, so I estimate the maximum BCD for 26T is around 80mm. By the same token, I estimate 36T is about the smallest you can go with 122mm BCD. That is in rough agreement with comments above.
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Old 01-08-12, 12:25 PM   #8
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I suppose I could hunt down a 38 inner and then build a freewheel cluster with some lower gearing. Unless of course, in a moment of weakness I misplace some cash on one of those pretty Gran Cru TA copies.
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Old 01-08-12, 12:55 PM   #9
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To stay sort original, you may need to switch to one of these, or the Stronglight or Sugino equivalent:



The Stronglights are uncommon, but obtainable, the SR's are more rare, and the Suginos are impossible to find (although I don't know why you would be looking for one). They all use the obsolete 86mm BCD which will let you get down to a 28T.
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