Originally Posted by blueskytheory
I have a late 80s Centurion Ironman Expert, the pink/yellow color scheme. I love the bike, rides beautifully, and has generational significance since it was my Dad's when he used to ride around the Tracy/Livermore hills. Right now it has the full Shimano 105 component group, downtube indexed shifters, with a 13/24 freewheel and 42/52 biopace chainrings (all standard stuff, nothing ever upgraded on the bike.)
Those were great bikes, comparable frames cost over a thousand bucks these days. Not everybody is down with the "Miami Vice" color scheme though...
Originally Posted by blueskytheory
I would like to change the gearing to be a little easier on hills; I can (just barely) climb steep grades in 42/24 but it wreaks havoc on my knees. I'd also like for my aging Dad to ride the bike more often, but he can't with the current gearing. So, before I buy the parts, I have a few questions about this upgrade:
1.) I want to put on a Shimano 6-speed Megarange freewheel, with a 13-34 range. (
http://harriscyclery.net/itemdetails...9&catalogId=39 ). The site says it will work with indexed shifting; does anyone have any experience with this? I'll be picking up the wide-range "Shimano MegaRange C201 rear derailleur." Essentially I guess I'm just wondering how clean the shifting is with a 10t jump from 24 to 34 in the rear; seems like it would have problems??
Should work just fine, I've got the same jump on the 11-34 7-speed freewheel on my Rambouillet, and it works like a charm.
Originally Posted by blueskytheory
2.) The harris cyclery page recommends the SRAM PC-58 chain. When I initially went to a LBS to talk about upgrading, they expressed some skepticism because, apparently, modern chainrings are designed to work with modern chains, and modern chains are more narrow to accommodate 8-9-10 speed spacings. Was the LBS misinformed, or?
The PC-58 isn't all that narrow, won't work with 9- or 10-speed setups, but it is my primary choice for 8-speeds or fewer.
Originally Posted by blueskytheory
3.) Finally, because I can't go below a 42 on the biopace 130mm chainrings, I was considering changing to round rings (i ride round on my other bike.) I've never quite understood if the crankarms are part of the biopace setup; can I just change both chainrings to round (a 38 and 50 probably), and leave the same crankarms? or are the crankarms "biopace" too? I don't see why the crankarms would matter since its the elliptical shape of the ring which makes biopace unique, but I'm not sure.
There is nothing "Biopace" about the arms, any 130 BCD chainrings will work with these, but I would leave the rings alone. Biopace is gentler on the knees, and it's a lot of expense to just lower the gearing by 10%
Sheldon "
http://sheldonbrown.com/biopace " Brown