Bicycle Mechanics - compact crank help please

Sheesh! I want to buy a compact crank for my early 90s Giant Cadex 980C bike which has a 7 speed Shimano 105 drive train. I didn't realize this task would be so difficult but it is. I don't want to spend a lot of money on gear for an older bike so I'm constantly watching Ebay....but there seem to be so many factors to consider and I'm turning to the forum for help.
Spec's I've been able to ascertain to date:

Shimano 105 bottom bracket; square taper, english, 68mm, 1.37, 113mm spindle, 130bcd, Chainline: 43.5

It's pre-index shifting so from what I've been told previously, I don't have to be to concerned about
Heck, I don't even know what half this means....I just want to get something compatible.

1. What is the easiest way to accomplish the task?
a. compact crank with Bottom bracket? is the cavity for the bottom bracket always the same for all bikes or where do I go to find out what I need for the Cadex 980C.
b. compact crank and spindle? if so, what specs matter? Which haven't I taken into consideration?
c. any other ideas?


Thanks for your help!

An early 90's 105 bike should have indexed DT shifters. Just go to:
Nashbarhttp://www.nashbar.com/profile_combo.cfm?combo=19404 .
They have a sale on a compact crank/BB combo. It should work fine with what you have. Good luck

Tim

Sheesh! I want to buy a compact crank for my early 90s Giant Cadex 980C bike which has a 7 speed Shimano 105 drive train. I didn't realize this task would be so difficult but it is. I don't want to spend a lot of money on gear for an older bike so I'm constantly watching Ebay....but there seem to be so many factors to consider and I'm turning to the forum for help.
Spec's I've been able to ascertain to date:

Shimano 105 bottom bracket; square taper, english, 68mm, 1.37, 113mm spindle, 130bcd, Chainline: 43.5

It's pre-index shifting so from what I've been told previously, I don't have to be to concerned about
Heck, I don't even know what half this means....I just want to get something compatible.

1. What is the easiest way to accomplish the task?
a. compact crank with Bottom bracket? is the cavity for the bottom bracket always the same for all bikes or where do I go to find out what I need for the Cadex 980C.
b. compact crank and spindle? if so, what specs matter? Which haven't I taken into consideration?
c. any other ideas?


Thanks for your help!

Sugino, Stronglight and TA make square taper compact cranks

Sugino, Stronglight and TA make square taper compact cranks

For that matter, why not just get 2 new rings? A 50 and 39 (http://www.bikemannetwork.com/biking/c/COMPCR7492130)would work nicely without need to mess with the bottom bracket. Alternatively, change the rear cassette to a 13 high gear. Same gear ratio and probably cheaper.

The new Tiagra compact (50-34) is great on my 86 Trek 400. The crankset can be found on ebay or $40 (+shipping), the external bearing BBs can be found inexpensively ($20 or so) all over the 'net. The shifting is on par with the Ultegra level compact on my Cannondale.