Replacing 50t chainring on Fuji Touring IVc
08-05-21, 09:38 AM
#1
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Replacing 50t chainring on Fuji Touring IVc
Hi all. I've tried posting this three times and keep getting booted off.
I would like to replace this 50T chainring with a 44T or 46T. It's a new bike to me, Fuji Touring IV. I think this is a 5arm square taper chain ring? The crank are Sugino (stock?) Can you recommend a new/vintage replacement one? Steel is preferred.
I'll be using a Cyclone FD.
Thanks!
I would like to replace this 50T chainring with a 44T or 46T. It's a new bike to me, Fuji Touring IV. I think this is a 5arm square taper chain ring? The crank are Sugino (stock?) Can you recommend a new/vintage replacement one? Steel is preferred.
I'll be using a Cyclone FD.
Thanks!
08-05-21, 10:57 AM
#2
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What model Sugino crank? Is it a triple? That’ll determine the bolt circle diameter (not just one standard, I’m afraid) and what ring to find.
08-05-21, 11:15 AM
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A Fuji Series IV with a Sugino triple?
it's almost certainly a 110bcd chainring that you're looking for. While I suspect you can find a steel 52t from some lower end cranks of the day, I think all the 46/44 ones you'll find will be aluminum
it's almost certainly a 110bcd chainring that you're looking for. While I suspect you can find a steel 52t from some lower end cranks of the day, I think all the 46/44 ones you'll find will be aluminum
08-05-21, 11:24 AM
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08-05-21, 11:25 AM
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08-05-21, 11:39 AM
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Why would you want steel? I can see it for a small granny chainring, but aluminum is the way to go for outer chainrings.
You can determine your bolt circle diameter (likely 144mm, 130mm, or 110mm) by measuring the center-to-center distance between two adjacent chainring bolts, and then using Sheldon Brown's conversion equation (see below).
If your crank can take a 40T or smaller ring, that rules out 144mm (minimum 42T or hard-to-find 41T). 36 or smaller rules out 130mm (minimum 38T or hard-to-find 34T).
"Measuring BCD: This 110 mm BCD ring measures 64.7 mm center-to-center
(or, from left side to left side, or right side to right side --easier to measure).
Multiplying this dimension by 1.701 will give you the actual BCD for a 5-bolt chainring. Use 1.155 for 3-bolt chainrings."
You can determine your bolt circle diameter (likely 144mm, 130mm, or 110mm) by measuring the center-to-center distance between two adjacent chainring bolts, and then using Sheldon Brown's conversion equation (see below).
If your crank can take a 40T or smaller ring, that rules out 144mm (minimum 42T or hard-to-find 41T). 36 or smaller rules out 130mm (minimum 38T or hard-to-find 34T).
"Measuring BCD: This 110 mm BCD ring measures 64.7 mm center-to-center(or, from left side to left side, or right side to right side --easier to measure).
Multiplying this dimension by 1.701 will give you the actual BCD for a 5-bolt chainring. Use 1.155 for 3-bolt chainrings."
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Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
08-05-21, 11:52 AM
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08-05-21, 12:06 PM
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08-05-21, 01:34 PM
#10
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I am trying to fit a Suntour Cyclone FD and the specs I've read say they like a 18T Max capacity. The previous owner had put a Shimano Exage 500 LX RD on it, with what I ASSUME is a matching FD and they had indexing shifters on flat bars.
I got rid of the flats and went back to drops, moved a set of friction shifters to the Downtube braze ons and fit a Cycle GT Long Cage RD. My goal is to use a cyclone FD, so I'd like to be inside the 18T capacity.
08-05-21, 02:09 PM
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170 is the length of the crank arms.
I think on the sugino ones I've seen the model name is on the outside of the arm. It might say something like Sugino AT or GT or VT? Could have worn off too.
If it is one of those then like others have said it will be a 110BCD chainring you will be looking for.
I think on the sugino ones I've seen the model name is on the outside of the arm. It might say something like Sugino AT or GT or VT? Could have worn off too.
If it is one of those then like others have said it will be a 110BCD chainring you will be looking for.
08-05-21, 03:23 PM
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Should also say you can only post 5X the first two days. After you hit 10 you can post all you want and add photos
08-05-21, 08:33 PM
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1983 was the last, if not the only, year for the Touring IV. The crank was a Sugino AT, 110x74 BCD triple, 50/42/28.
If the freewheel is the original 14-15-17-19-21-24, and if you want to keep the 42T middle ring, the only two outer rings that don't give stupid gearing with wonky gaps and a ton of duplicate gears are the 50T the bike was spec'd with, (1.5-step + granny,) and a 45T (half-step + granny.) With a 46T outer, you'd want to drop the middle ring to a 39... very similar gearing, just ~8% lower across the board.
If you haven't got the Cyclone front derailleur in hand, a Cyclone GT would be the one to get. A Suntour Mountech is original spec.
1983 Fuji Catalog
Visual Gear Calculator, so you can play with rings and see what you want.
--Shannon
If the freewheel is the original 14-15-17-19-21-24, and if you want to keep the 42T middle ring, the only two outer rings that don't give stupid gearing with wonky gaps and a ton of duplicate gears are the 50T the bike was spec'd with, (1.5-step + granny,) and a 45T (half-step + granny.) With a 46T outer, you'd want to drop the middle ring to a 39... very similar gearing, just ~8% lower across the board.
If you haven't got the Cyclone front derailleur in hand, a Cyclone GT would be the one to get. A Suntour Mountech is original spec.
1983 Fuji Catalog
Visual Gear Calculator, so you can play with rings and see what you want.
--Shannon
