Dura Ace RD-7402 Long Cage Conversion

[vxchtx]

hi again :-)


so i really love the 8 speed dura ace 7400 groupset. has been my favorite since i started to get more interested in bikes.

i want to build up one of my klein quantum bikes with this groupset, however i would love to have a more mountain oriented cassette.

since i could not find a 130mm 34T chainring to fit to the 7402 crankset i thought it might be possible to convert the rear derailleur to a long case version in order to fit say a 32T cassette.

i know this has been done before with some older shimano 600 (RD-6207 & 6210).
the longer cage of the 600 series has been put on the RD-7402 in order to fit larger cassettes.

now either the 6207 and 6210 are really rare and i can't seem to find them anywhere for a decent price.

so i was wondering if the same thing would be possible with a slightly younger shimano derailleurs. i mainly thought of the RD-6500 (long cage version) and the shimano light action derailleurs.


i would greatly appreciate any help in my quest to make my dream 7400 setup. :bike:

[cnighbor1]

Converting Dura-Ace 7400 rear derailleur to a longer cage
Yes Davidson cycles did it many times
and Robert Freeman told me about it
The Dura-Ace 7400 rear derailleur short cages arms can be replaced with the Shimano 600 rear derailleur long cage arms
Just unbolt DA arms and install 600 arms
One item The pulley bolts don't sit flush with with face of cage and hang up
Need to buy bolts that counter sink about $10 I used a drill bit held by hand and just turned to counter sink hole to allow bolts to sit flush
Works great and I run a 29t rear cog




so i really love the 8 speed dura ace 7400 groupset. has been my favorite since i started to get more interested in bikes.

i want to build up one of my klein quantum bikes with this groupset, however i would love to have a more mountain oriented cassette.

since i could not find a 130mm 34T chainring to fit to the 7402 crankset i thought it might be possible to convert the rear derailleur to a long case version in order to fit say a 32T cassette.

i know this has been done before with some older shimano 600 (RD-6207 & 6210).
the longer cage of the 600 series has been put on the RD-7402 in order to fit larger cassettes.

now either the 6207 and 6210 are really rare and i can't seem to find them anywhere for a decent price.

so i was wondering if the same thing would be possible with a slightly younger shimano derailleurs. i mainly thought of the RD-6500 (long cage version) and the shimano light action derailleurs.


i would greatly appreciate any help in my quest to make my dream 7400 setup.

[rccardr]

I would be tempted to either use a Woolftooth or a Deore RD instead of trying to adapt a longer cage to a 7402 RD. You need the longer RD body to clear the Small/big combination; a longer cage doesn’t do that for you.

[jc031699]

I would be tempted to either use a Woolftooth or a Deore RD instead of trying to adapt a longer cage to a 7402 RD. You need the longer RD body to clear the Small/big combination; a longer cage doesn’t do that for you.


Unfortunately 7400 is not compatible with the MTB RD’s to the best of my knowledge. That intercompatibility between dura ace and the rest of the shimano universe did not start until 7700 (9 speed).

https://www.sheldonbrown.com/dura-ace.html

Using a RoadLink or knockoff is your best bet.

130BCD only goes down to 38t chainring size.


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[mikehkaiser]

Wolftooth roadlink would get you extra capacity. Perhaps paired with the longer cage conversion, you'd be able to stretch it to 32T.

You could also use a tripleizer ring on the crankset, but then you'd need a new bottom bracket to push the little ring away from the chainstays, and that, in total, would probably mess with chainline.

In all, turning the 7402 crank into a triple is not a good idea, but it came to mind as an alternative way to expand gearing capacity.

[Mike V]

Link show converted derailleur

https://m.facebook.com/137062087082/posts/heres-something-you-dont-see-everyday-a-long-cage-dura-ace-rd-7402-thats-an-8-sp/10152581816167083/

[vxchtx]

yes that is the one i saw and where i got the idea from to make such a conversion. anyone know it a shimano 105 (RD-1056) would be compatible with the dura ace 7402.....

[rccardr]

Unfortunately 7400 is not compatible with the MTB RD’s to the best of my knowledge. That intercompatibility between dura ace and the rest of the shimano universe did not start until 7700 (9 speed).

https://www.sheldonbrown.com/dura-ace.html

Using a RoadLink or knockoff is your best bet.

Generally agree. However, using Sheldon's Alternate B cable placement (same link as above, just down the page) allows the Deore RD to interface properly with 7402 shifters.

Ultimately, the lesson here is that to work with a large rear cog, one needs the longer body and geometry of an RD meant to work with them, or a fix such as the Roadlink. The longer cage helps with wrap, but not the small/big RD pulley wheel clearance problem typical of these installations.

[jc031699]

Generally agree. However, using Sheldon's Alternate B cable placement (same link as above, just down the page) allows the Deore RD to interface properly with 7402 shifters.

Ultimately, the lesson here is that to work with a large rear cog, one needs the longer body and geometry of an RD meant to work with them, or a fix such as the Roadlink. The longer cage helps with wrap, but not the small/big RD pulley wheel clearance problem typical of these installations.


Thank you for the correction-


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