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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 09-18-06, 09:12 AM   #1
jzztchr
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BB and front derailleur question--upgrade

Hi,
I'm in the process of upgrading the drivetrain on my '81 Panasonic DX-4000 sport touring model. Right now, its got Shimano Ultegra 52/40 crank assemblies w/165 mm length pedal cranks on a 12 speed with 12-26 gearing freewheel--not freehub. The pedals are a little too short and at 6'2" with 34 inch inseam I'm thinking of 175's or at least 172.5's. These are all on a 61 cm frame which I really like and which is comfortable for long rides. My current inherited chain is stretched and needs to be changed out anyway, and I'd like to go to the 172.5 or 175's. I'd also like a wider gear range as there is a fair bit of climbing in the Hudson Valley.

I've assembled most of the parts to do this without spending much money: SRAM wide range 9-speed cassette (11-34); KMC 9-speed chain;Shimano LX rear derailleur(long cage);MAVIC aero 700mm rear wheel w/quick release. Conti rear tire and tube. I've already upgraded to clipless pedals for not much $, and I'm very happy with them.

Ill be keeping the Ultegra brakes and the Shimano 600 friction shifters. They work just fine and I like simple. The Richey compact double (50-36 non-carbon) w/ 175's looks attractive.

RE BB: How wide should do I need to go? 118.3 ?! I know the current BB which is believe is 108 or 110 is too narrow for the 9-speed...I'm also wondering if the wide-range gearing presents any issues here? Also, what is your advice on BB type (octalink, ISIS, mega)

Second, is this going to require a new front derailleur?

My rationale for the upgrade is mixed. Some of the current gear needs replacement/renewal (the chain) and some (the cranks) would be better in a newer size. Finally, if I decide to away from the old Cr-Mb steel frame, I can take this stuff with me, and just sell the frame, which would be good for a single-speed conversion (much prized in nearby NYC).

If any one has some advice on this, I would be appreciative. Thank you.
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Old 09-18-06, 09:26 AM   #2
rcnmoon
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Without addressing all the questions.
1) You may have spacing/clearance problems using the 9 speed cassette on that frame. Before going too far with it determine if it will fit. You might consider looking for a 13 or 14-34 6 speed freewheel to replace your existing one. The 172.5 crank wi probably work for you. With that you may not need a new front der.
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Old 09-18-06, 12:24 PM   #3
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Quote:
Originally Posted by jzztchr
I've assembled most of the parts to do this without spending much money: SRAM wide range 9-speed cassette (11-34); KMC 9-speed chain;Shimano LX rear derailleur(long cage);MAVIC aero 700mm rear wheel w/quick release. Conti rear tire and tube. I've already upgraded to clipless pedals for not much $, and I'm very happy with them.

Ill be keeping the Ultegra brakes and the Shimano 600 friction shifters. They work just fine and I like simple. The Richey compact double (50-36 non-carbon) w/ 175's looks attractive.

RE BB: How wide should do I need to go? 118.3 ?! I know the current BB which is believe is 108 or 110 is too narrow for the 9-speed...I'm also wondering if the wide-range gearing presents any issues here? Also, what is your advice on BB type (octalink, ISIS, mega)

Second, is this going to require a new front derailleur?

My rationale for the upgrade is mixed. Some of the current gear needs replacement/renewal (the chain) and some (the cranks) would be better in a newer size. Finally, if I decide to away from the old Cr-Mb steel frame, I can take this stuff with me, and just sell the frame, which would be good for a single-speed conversion (much prized in nearby NYC).

If any one has some advice on this, I would be appreciative. Thank you.
Your best bet would be to calculate the proper chainline and buy the bottom bracket accordingly. Go over to Sheldon Brown's site and read how to do it. I've done this recently for a bike that had shifting problems and it cleared them right up.

Rcnmoon is incorrect in that you will have width issues with a modern wheel. A road wheel has an axle width of 130mm. Your bike is probably has dropouts that are 126mm. That's only 4mm of width difference which is easily spread by hand - i.e. no cold setting. It will make getting the wheel in and out a little tougher but it's not that bad.

As for the front derailler, no you won't need to change it. Since you are using friction shifting, you can use anything you like, just make sure you set the limit screws right. If, on the off chance that it doesn't shift well, get a new front derailler. But try the old one first.
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