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Old 08-23-10, 01:16 PM   #1
modernfuturist
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Half Step Gearing and Suggestions for New Chainring

I have a half step gearing setup (48-44-28) on my 1983 Specialized Expedition.

When I went fully loaded touring, I found myself rarely using the 48 chainring, and I'm wondering if I should just swap it out.

Any recommendations for a chainring, and would it generally be a 110 bcd diameter?
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Old 08-23-10, 02:34 PM   #2
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Do you have the original freewheel in back? Half step gearing uses a widely spaced rear gears and the two chainrings in front split the difference between the rear cogs. Ie, you shift the front to shift one gear and shift the rear to shift two gears. If you swapped out the freewheel for a conventionally spaced freewheel, the whole half step setup doesn't make sense anymore.

If you still have the Sugino AT crankset it is a 110/74 BCD. Chainrings are readily available and all you need to do is pick your gearing. You can go down to a 24 tooth ring on the 74, 33 is the minimum on the 110.

BTW, nice bike!!
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Old 08-23-10, 03:53 PM   #3
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Odd numbered chainrings are getting very hard to find anymore. You have a 4-tooth gap now. Moving to a 46-42 would be easy; moving to 44-40 may be a bit harder unless you want to run what will likely be an inner chain ring on the outside (I do, but you may not). I think 46-42 is the better option. You can get 45-tooth chainrings, but 41's are almost impossible to find.

Your other option is up-sizing the rear freewheel/cassette. Many touring bikes came with 28-tooth or occasionally a 30. You can still find 32's and 34's occasionally, especially 5 or 6-speed (stay away from "Mega Range" branded ones). This will spread out your "gaps", but if you have a 6-speed, 4-tooth will be fine.
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Old 08-23-10, 07:31 PM   #4
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Odd numbered chainrings are getting very hard to find anymore.
TA make all those difficult to find chain rings, super quality too.
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Old 08-24-10, 07:44 AM   #5
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I am not sure what the question is. If you rarely use your largest chainring and are wondering if you should swap it for something else, what would you like to gain in exchange for that?
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Old 08-24-10, 06:25 PM   #6
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Good question ...

Quote:
Originally Posted by LHT in Madison View Post
I am not sure what the question is. If you rarely use your largest chainring and are wondering if you should swap it for something else, what would you like to gain in exchange for that?
Good question ...
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Old 08-24-10, 07:05 PM   #7
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You could drop the outside ring entirely , bolt on a chainguard ring instead, for the 44t
http://cyclocrossworld.stores.yahoo....ealchgufo.html
and put a 24t granny gear on the 74 BCD..
a shift pin ramped chainring will up shift from the granny quicker, But I usually do that shift at the top of a climb anyway, when the pedal force needed is slight. Salsa (QBP) or TA are Ergal , Sugino are a softer aluminum but cost less too.

a surly Stainless chain-ring is one that will be long wearing , but has no ramps and such

Im still running steel chainrings I fitted in 90, no ramps on those I friction bar end shift them just fine..

Last edited by fietsbob; 08-24-10 at 07:10 PM.
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Old 08-25-10, 12:03 PM   #8
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Quote:
Originally Posted by LHT in Madison View Post
I am not sure what the question is. If you rarely use your largest chainring and are wondering if you should swap it for something else, what would you like to gain in exchange for that?
I guess I didn't completely understand the concept of half step gearing. I had always thought that the main benefit was that it made it easier to shift from the 48 and 44 rings, but I didn't understand that the freewheel (as Iowegian pointed out) also had a contribution to the half step gearing.

I guess I'm considering either swapping out the 48 or the 44, so I can get more coverage in the middle of my gear range, but with my current original freewheel, I guess it doesn't really matter.
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