Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

What do I have here? (Shimano content)

Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

What do I have here? (Shimano content)

Old 05-22-16, 09:27 AM
  #1  
leaping_gnome
Senior Member
Thread Starter
 
leaping_gnome's Avatar
 
Join Date: Jun 2008
Location: Antelope Valley, SoCal
Posts: 470

Bikes: 1975 Eisentraut Ltd, 1995 Trek 7000 MTB, 2007 Masi Vincere, 1974 Masi GC, 1981 Specialized Allez, 1984 Specialized Sequoia

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
What do I have here? (Shimano content)

Sorry if this is slightly OT but you are the guys I can best relate to. I recently bought this bike, a 95 Specialized M2, with a full Dura Ace 7402 group. That in itself was unusual and I can only assume that the original owner (not the seller) equipped the bike that way, but the gear ratios and rear derailleur really caught my eye. This appears to be a wide-ratio RD-7402 derailleur and Deore XT-M7XX 8-speed cassette. The cage on the derailleur looks like it also came from the Deore line! Was this configuration of Dura-Ace 7400 and Deore ever sold?
I am definitely pleased with the combo because the gear ratios will allow some pretty unlimited climbing potential. The rivets on the 1st gear (Ti?) to aluminum four finger spider are loose, so I will eventually have to repair or replace it. So if anyone wants to chime in with Dura Ace 7402/Deore knowledge I would love to know more. Is it possible to graft a Deore cage onto a 7402 derailleur?

I included a photo of the Deore RD-M730 derailleur cage for reference from Velobase

Tia - Jim BTW - there's more photos of the whole bike on my Flickr album
IMG_5905 by Jim Harris, on Flickr
IMG_5896 by Jim Harris, on Flickr

RD-M730 derailleur cage Photo Credit: VeloBase User tommy
leaping_gnome is offline  
Old 05-22-16, 09:48 AM
  #2  
Lazyass
Senior Member
 
Lazyass's Avatar
 
Join Date: Jul 2008
Location: NC
Posts: 8,171

Bikes: Vintage steel, aluminum, modern carbon disc, single speed, MTB's, the works

Mentioned: 58 Post(s)
Tagged: 0 Thread(s)
Quoted: 1910 Post(s)
Likes: 0
Liked 0 Times in 0 Posts






Lazyass is offline  
Old 05-22-16, 02:02 PM
  #3  
leaping_gnome
Senior Member
Thread Starter
 
leaping_gnome's Avatar
 
Join Date: Jun 2008
Location: Antelope Valley, SoCal
Posts: 470

Bikes: 1975 Eisentraut Ltd, 1995 Trek 7000 MTB, 2007 Masi Vincere, 1974 Masi GC, 1981 Specialized Allez, 1984 Specialized Sequoia

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Oooookay, care to elaborate? I'm glad to see other types, what model designation were they? What application?
leaping_gnome is offline  
Old 05-22-16, 03:54 PM
  #4  
QuangVuong
******
 
QuangVuong's Avatar
 
Join Date: Apr 2013
Location: Villawood, Sydney
Posts: 219

Bikes: 89 Centurion Carbon, 91 Peugeot Izoard, 90s Giant Cadex 980c

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
RD cages are interchangeable. Someone's gone and swapped the short DA one out for a different cage, probably off that Deore RD.

Ive done it myself before on other RDs. The cage length really only allows for a longer chain, which is useful for a triple, but due to the RD body length, you're still stuck at about a max 28t on the 7400 RD. Unless the top jockey wheel of the Deore cage is lower than where the DA jockey wheel was.
QuangVuong is offline  
Old 05-22-16, 04:11 PM
  #5  
T-Mar
Senior Member
 
Join Date: Nov 2004
Posts: 17,864
Mentioned: 434 Post(s)
Tagged: 1 Thread(s)
Quoted: 2490 Post(s)
Likes: 0
Liked 74 Times in 67 Posts
I've never seen a catalogued RD-74xx rear derailleur with a long cage. They are easy enough to cobble together with cages from other Shimano models of the same era. However, this is generally done to facilitate running a triple crankset with a granny gear. The substitution of a Shimano ATB cage should not allow you run a larger cog, as the dimension between the pivot to jockey pulley axes are common. You can usually cheat a couple of teeth's worth by moving the wheel back in the dropout but this isn't possible with a vertical dropout. The only way to increase the large cog capacity would be to install a longer dropout hanger or grind the tops of the dropout slot. Beyond that, you'd have to carefully manage the chain length to run the shortest possible chain or get really creative and use new upper and lower pivot castings with a longer drop and/or steeper cog tracking angles.
T-Mar is offline  
Old 05-22-16, 06:25 PM
  #6  
leaping_gnome
Senior Member
Thread Starter
 
leaping_gnome's Avatar
 
Join Date: Jun 2008
Location: Antelope Valley, SoCal
Posts: 470

Bikes: 1975 Eisentraut Ltd, 1995 Trek 7000 MTB, 2007 Masi Vincere, 1974 Masi GC, 1981 Specialized Allez, 1984 Specialized Sequoia

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks QV and T-Mar
You've confirmed what I suspected, that this RD may be assembled using a Deore cage. Yup, the cage clears the 28t second cog just fine but rides on the 32t first cog. I guess that's why it's loose. The long cage may be overkill, for sure, but a mid cage may have an advantage for a bike with vertical dropouts.

Thanks

Jim
leaping_gnome is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
bikebreak
General Cycling Discussion
1
05-19-13 04:01 PM
bronj
Road Cycling
20
08-03-12 09:28 AM
Mr Danw
Classic & Vintage
6
08-27-10 08:31 AM
OneTinSloth
Singlespeed & Fixed Gear
6
07-04-04 03:06 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.