DA 7850/6700 freehub compatibility

[marciero]

In case I need a new one- 6700 freehub is $19 at Bike Nashbar. Will this fit on my 7850 hub?

[oldpotatoe]

Originally Posted by marciero

In case I need a new one- 6700 freehub is $19 at Bike Nashbar. Will this fit on my 7850 hub?

Sorry, no..much different axle, cones, nuts, etc.., 7850-6700

[marciero]

Originally Posted by oldpotatoe

Sorry, no..much different axle, cones, nuts, etc.., 7850-6700

Thanks. Is this part of the 7800 weirdness that carried over to 7850, minus the tall splines, or is 7900 also not compatible with 6700 cassette body?

One more question: I have some cassette body play (to be clear I was using "freehub" and "cassette body" to mean the same thing). Is that adjustment similar to hub bearing adjustment? It looks to be from an exploded diagram I saw.

[oldpotatoe]

Originally Posted by marciero

Thanks. Is this part of the 7800 weirdness that carried over to 7850, minus the tall splines, or is 7900 also not compatible with 6700 cassette body?

One more question: I have some cassette body play (to be clear I was using "freehub" and "cassette body" to mean the same thing). Is that adjustment similar to hub bearing adjustment? It looks to be from an exploded diagram I saw.

The 7801 was like 7800..in fact, the RH cone was permanently affixed to axle..kill a cone, buy a new axle. The FHB did NOT bolt to the hub body, like all other shimano rear hubs..for 7800/7801..same deep spline gig. 7850 went back to FHB bolted to hub body(which shimano still owns the patent for) and to a titanium HG FHB(7800/7801 was aluminum) that would accept any shimano compatible 8/9/10s(NOT 11s..doh!!)..BUT the design of 7800/7801 was very similar to Campagnolo of the time.

6700-7900? I don't think so..the 6700 bearing balls are 1/4 inch, the 7900 are 3/16..the axles are way different as well..6700 just a pretty normal, threaded 10by1 axle..the 7900 a one piece, I think still aluminum..

[Gummee]

I don't know the specifics of the hub in question, but historically D/A only works with D/A

You can sometimes swap in XTR with D/A and XT with Ultegra

HTH

M

[rccardr]

Originally Posted by Gummee

I don't know the specifics of the hub in question, but historically D/A only works with D/A

You can sometimes swap in XTR with D/A and XT with Ultegra

HTH

M

Not 'zackly correct. Only 740X 6-7-8 speed is unto itself, and that only with regard to indexing components. In fact, 7403 hubsets are stillvery highly regarded among the 8-9-10 speed set.

7700 and 7800 are compatible with all other Shimano road 6-7-8-9-10 speed systems with the exception of 10 speed Tiagra, and that even includes the non-group specific stuff like R500 and R600. There are some minor things to look out for with regard to brake lever/caliper matching with the later stuff, but otherwise a pretty comparible universe of components.

[Gummee]

Originally Posted by rccardr

Not 'zackly correct. Only 740X 6-7-8 speed is unto itself, and that only with regard to indexing components. In fact, 7403 hubsets are stillvery highly regarded among the 8-9-10 speed set.

7700 and 7800 are compatible with all other Shimano road 6-7-8-9-10 speed systems with the exception of 10 speed Tiagra, and that even includes the non-group specific stuff like R500 and R600. There are some minor things to look out for with regard to brake lever/caliper matching with the later stuff, but otherwise a pretty comparible universe of components.

You're correct about cassettes and stuff, but not when you're talking about mixing and matching FH bodies, derailleur cages, etc. I know firsthand that XTR works with D/A (of a certain vintage) but won't work with Ultegra.

Since Shimano started making long cage road derailleurs, I haven't had to play mix-n-match in a while.

M

[steelbikerider]

The replacement for a 7850 hub is an XTR freehub but I can't locate the part number now.

[oldpotatoe]

Originally Posted by steelbikerider

The replacement for a 7850 hub is an XTR freehub but I can't locate the part number now.

Same part number for both..

Y-3CN98080

[marciero]

Thanks all. In case I need to go that route via ebay I can make sure.

[dddd]

I recall that the ti freehub body only saved ~25 grams versus the steel freehub body from my 640* 8s Ultegra freehub, and also that the Ti freehub spaced the cassette at least a couple of mm further out from the driveside flange of the hub.
I kept it on there on my rear CX wheel anyway, but removed a washer and the 12t cog that I never used anyway. So with the added weight savings of the lost cog, it was perhaps worth the effort (the freehub body itself was a "freebie" used leftover bit from a damaged 7700 hub).

It is often the case that when swapping Shimano freehub bodies between component tiers that the mounted width changes, just as in the above example. It is commonly thought that the spline-mounted freehub bodies are all the same in this regard, but often they are quite different unfortunately. The cones and sealing mechanisms on the axle's drivside are often dedicated to their mating freehub body as well, though the main shield can usually be pried out and transplanted (at some risk of damage) from one freehub body to another.