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.

Derailleur question

Old 06-03-17, 10:21 PM
  #1  
Specialagentoc
Newbie
Thread Starter
 
Join Date: Jun 2017
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Derailleur question

I am attempting my first rebuild on a road bike. I bought a 1979 Raleigh Rampar R One. I did mechanical check and all components check out aside from needing a good cleaning and lube aside from the rear derailleur which is bent badly and has to be replaced. The. Ike is totally original parts and I want to try and keep it as original as I can but I am thinking of replacing the derailleur with a more modern one. So I am of the understanding that since it is friction shifting I have a lot of options. Does anyone have suggestions of a good replacement and do I need a long bracket or short? I am am. PT looking to spend a great deal of money to replace it. Thank you in advance.

Brian O'Connor
Specialagentoc is offline  
Old 06-03-17, 11:10 PM
  #2  
nfmisso
Nigel
 
nfmisso's Avatar
 
Join Date: Mar 2011
Location: San Jose, CA
Posts: 3,010

Bikes: 1980s and 1990s steel: CyclePro, Nishiki, Schwinn, SR, Trek........

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 381 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Brian; we know very little about your bike.

What RD was on it originally?
What is the freewheel/cassette range?
Number of cogs on the freewheel/cassette?
nfmisso is offline  
Old 06-04-17, 06:00 AM
  #3  
seedsbelize 
Refugee
 
Join Date: Nov 2010
Location: Tixkokob, Yucatán, México
Posts: 11,250
Mentioned: 93 Post(s)
Tagged: 1 Thread(s)
Quoted: 4708 Post(s)
Liked 24 Times in 22 Posts
I had one of those, bought new. Short cage should be fine. I like the old Suntour open cage derailleurs--no need to break the chain to remove. Off the top of my head, these include the cyclone, vx, vgt luxe for sure. There might be others.
seedsbelize is offline  
Old 06-04-17, 03:54 PM
  #4  
70sSanO
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 1,322

Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium DA, 1992 Serotta T-Max, 1995 Trek 970

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 236 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
A lot of it depends on how modern, the type of look you want, and what you want to spend. If it were me, I'd probably go with at least a medium cage and possibly a long cage. Something like a Shimano MT60 might have the right look and it would be an upgrade.

John
70sSanO is offline  
Old 06-04-17, 05:19 PM
  #5  
SkyDog75
Senior Member
 
Join Date: May 2011
Location: Upstate NY
Posts: 3,818

Bikes: Bianchi San Mateo and a few others

Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 632 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by Specialagentoc View Post
I bought a 1979 Raleigh Rampar R One. I did mechanical check and all components check out aside from needing a good cleaning and lube aside from the rear derailleur which is bent badly and has to be replaced... So I am of the understanding that since it is friction shifting I have a lot of options.
Your understanding is correct. Your options are wide open since you don't have to worry about indexing.

Originally Posted by Specialagentoc View Post
The. Ike is totally original parts and I want to try and keep it as original as I can but I am thinking of replacing the derailleur with a more modern one.
Why replace the derailleur with a more modern one? New derailleurs aren't necessarily better; they're just compatible with indexed shifters.

Originally Posted by Specialagentoc View Post
Does anyone have suggestions of a good replacement and do I need a long bracket or short?
SunTour derailleurs from the '70s and '80s worked really well and would look right at home on your bike. Here's an inexpensive Raleigh-branded SunTour 7 GT (long cage) on eBay:
SUNTOUR - RALEIGH - REAR DERAILLEUR | eBay

Whether you need a long cage derailleur depends on your bike's gearing, both front and rear. The bigger the difference between your lowest and highest gear, the more chain slack the derailleur needs to be able to handle, and generally that means a longer cage. A derailleur's ability to take up slack is measured by its "wrap capacity", typically expressed in a number of teeth. You can calculate the wrap capacity you need with a little math:

(big chainring - small chainring) + (big cog - small cog) = wrap capacity

Once you've done the math using your bike's gearing, you can compare that against published numbers for derailleurs you're looking at. Not every short/medium/long cage derailleur can handle the same capacity, but here are some numbers for reference:

1970s SunTour V series:
V (short cage) = 24 teeth
V-T (medium cage) = 28 teeth
V-GT (long cage) = 36 teeth

Shimano 105 5600 (circa 2006):
SS (short cage) = 29 teeth
GS (medium cage) = 37 teeth

Shimano Ultegra 6700 (circa 2009):
SS (short cage) = 33 teeth
GS (medium cage) = 39 teeth

Shimano SGS (long cage) derailleurs are typically only found in their mountain bike lineups.

Last edited by SkyDog75; 06-04-17 at 05:22 PM.
SkyDog75 is offline  
Old 06-04-17, 09:02 PM
  #6  
maddog34
Senior Member
 
maddog34's Avatar
 
Join Date: Jul 2015
Location: NW Oregon
Posts: 1,391

Bikes: !981 Trek 930R Custom, Diamondback ascent with SERIOUS updates, and a trek 6700 with updates

Mentioned: 11 Post(s)
Tagged: 1 Thread(s)
Quoted: 551 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
like this one?
Rampar Road Bike - bike

the rear derailleur is a MID CAGE length... not a short cage... and a short cage der. would not like your freewheel.

get a suntour VT or VGT... there are a few on Ebay, usually. it will be similar to the stock part, and will work great... i've used several through the years...

count the number of teeth on the large gear of your freewheel, and get the appropriate length cage, as Skydog mentioned/listed.

Last edited by maddog34; 06-04-17 at 09:07 PM.
maddog34 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
stucon
Classic and Vintage Sales
3
05-06-16 09:21 PM
cam117
Touring
17
02-18-10 02:20 AM
b_young
Commuting
24
09-20-07 02:23 PM
Peek the Geek
Mountain Biking
15
06-10-06 10:41 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.