7400 6 speed question

[Blue4now]

I am building a 7400 6 speed setup and finally found a Dura-Ace 6 speed cassette. Just want to confirm it will work on a 7400 freehub with whatever spacer is necessary correct?

I see all the 7400 freehubs advertised at 7,8 and 9 speed but its got to work with a 6 right?

[bob_in_pa]

Originally Posted by Blue4now

I am building a 7400 6 speed setup and finally found a Dura-Ace 6 speed cassette. Just want to confirm it will work on a 7400 freehub with whatever spacer is necessary correct?

I see all the 7400 freehubs advertised at 7,8 and 9 speed but its got to work with a 6 right?

For a 6 speed cassette I believe you'll need a uni-glide FHB with the reduced diameter external threads. Depending on the spacing of your frame that would limit you to a fh-7400 (126mm) or fh-7402 (130mm).

-Bob

[rccardr]

There are a bunch of ways to make this work, but here’s a primer:
Dura Ace 740X cassette and freewheel spacing is the same as all other Shimano indexed components.
As long as you are using a 740X shifter and RD (they are all interchangeable within the 740X component family), you can use ANY Shimano/SRAM/Miche/IRD sprocket set that matches the number of indexed gears in the shifter.
With regard to my understanding of your specific question, you can use any HG 6 speed cassette on a few 7 and all 8-9-10 speed Shimano freehubs as long as you use the appropriate 6 speed spacers between the sprockets and the correct large spacer (4.5 mm for 8-9-10, 7 speed will require messing about with thinner ones to get it right).
If you prefer to use UG sprockets, then ANY Shimano 6-7 speed freehub made for UG or UG/HG (see note below) will work just fine unless you want to use a 12 tooth UG sprocket, which typically means a DA freehub with the reduced end diameter (13 tooth and larger first sprocket does not require this).

Dura Ace rear freehub (not freewheel) hubs: 7400 = 6 speed UG only; 7401 = 7 speed, UG only; 7402 = 8 speed, UG only; 7403 = 8 speed, UG/HG compatible. 7400 & 7401 are 126 OLD, 7402 &7403 are 130mm.

The best non-DA UG/HG Shimano freehub hubs with which I am familiar are 7 speed 6401 Ultegra/Tricolor (126 OLD) and 6402 8 speed Ultegra /Tricolor (130mm).

PM me for more information and details if I’ve missed the mark for you here.

[Blue4now]

Originally Posted by rccardr

There are a bunch of ways to make this work, but here’s a primer:
Dura Ace 740X cassette and freewheel spacing is the same as all other Shimano indexed components.
As long as you are using a 740X shifter and RD (they are all interchangeable within the 740X component family), you can use ANY Shimano/SRAM/Miche/IRD sprocket set that matches the number of indexed gears in the shifter.
With regard to my understanding of your specific question, you can use any HG 6 speed cassette on a few 7 and all 8-9-10 speed Shimano freehubs as long as you use the appropriate 6 speed spacers between the sprockets and the correct large spacer (4.5 mm for 8-9-10, 7 speed will require messing about with thinner ones to get it right).
If you prefer to use UG sprockets, then ANY Shimano 6-7 speed freehub made for UG or UG/HG (see note below) will work just fine unless you want to use a 12 tooth UG sprocket, which typically means a DA freehub with the reduced end diameter (13 tooth and larger first sprocket does not require this).

Dura Ace rear freehub (not freewheel) hubs: 7400 = 6 speed UG only; 7401 = 7 speed, UG only; 7402 = 8 speed, UG only; 7403 = 8 speed, UG/HG compatible. 7400 & 7401 are 126 OLD, 7402 &7403 are 130mm.

The best non-DA UG/HG Shimano freehub hubs with which I am familiar are 7 speed 6401 Ultegra/Tricolor (126 OLD) and 6402 8 speed Ultegra /Tricolor (130mm).

PM me for more information and details if I’ve missed the mark for you here.

WOW thanks for that, so have a Dura-ace 14-26 cassette incoming and I hope I didn't make a mistake pulling the trigger on it, I want to buy a 7400 wheelset with a freehub, to be used with said cassette and a 7400 RD and 6 speed downtube shifters. So I think you are saying that will work with the correct spacer? my frame is 126mm spacing

[Blue4now]

Originally Posted by bob_in_pa

For a 6 speed cassette I believe you'll need a uni-glide FHB with the reduced diameter external threads. Depending on the spacing of your frame that would limit you to a fh-7400 (126mm) or fh-7402 (130mm).

-Bob

thanks, its 126 so a 7400 fh will work which is what I was hoping!

[bob_in_pa]

Originally Posted by Blue4now

thanks, its 126 so a 7400 fh will work which is what I was hoping!

Yes it will work but it gets a little tricky. fh-7400 came in 2 different favors, fh7400-6 (6 speed, 126mm old) and fh-7400-7 (7 speed, 126mm old). There never was a fh-7401 though it has become a common term.

What's tricky is while both fh-7400-6 and fh-7400-7 are each 126mm old there's a spacer that gets moved between non-drive side and drive side depending on 6 or 7 speed. The thing is only about 2mm thick so it will likely work either way but Shimano did call it out in the service instructions.

-Bob

[Brian Smith]

If you're using 6-speed, and you didn't already have the cassette and freehub, why did you not choose a freewheel? Did it just not occur to you?
With 126mm spacing, using a 8&up speed freehub introduces more wheel dish than would have been prudent at the time (hence the move to 130mm) and if you were to use a Dura-Ace (or Ultegra, etc.) 6s freewheel, you are then completely free to choose from hundreds of freewheel hubs which are comparative bargains for top shelf items.

I think you'd enjoy more benefits and flexibility, if you're sticking with 126mm, to go the route of a 6s freewheel and whatever freewheel hub you choose.

[Blue4now]

[QUOTE=Brian Smith;2986039]If you're using 6-speed, and you didn't already have the cassette and freehub, why did you not choose a freewheel? Did it just not occur to you?
With 126mm spacing, using a 8&up speed freehub introduces more wheel dish than would have been prudent at the time (hence the move to 130mm) and if you were to use a Dura-Ace (or Ultegra, etc.) 6s freewheel, you are then completely free to choose from hundreds of freewheel hubs which are comparative bargains for top shelf items.

I think you'd enjoy more benefits and flexibility, if you're sticking with 126mm, to go the route of a 6s freewheel and whatever freewheel hub you choose.[/

You may be on to something. I guess I didn’t consider that option but it appears way less expensive

[rccardr]

If the frame is anything other than carbon or glued graphite or Alan, then a 130mm hub will fit in very, very easily. Yes,there are naysayers (some of whom I highly respect) but having done it literally dozens and dozens of times with many miles on the finished product, can tell you from personal experience that it’s No Big Thing.

So yeah, you could use a 6 speed 7400 freehub and run a 6 speed DA/Shimano UG cassette and if 14-26 is optimum gearing, then it will make you happy and last for many thousands of miles.

Or, maybe you’d really like a 12-28 with some flexibility for later on down the road. Use a later DA hubset and run 6 speed HG on it for now with a 4.5mm backside spacer & take your pick of any combination of sprockets you want. Later on, go all the way up to 10 speed if you want (the right downtube shifter accepts appropriate 7-8-9-10 speed indexing pods) & all you really have to change are the cassette, chain, and pod. Neat!

[alexihnen]

^ Yep. What he said.

[jamesdak]

Yep, I'll agree with these two. Been doing that for years.

[Blue4now]

A wealth of knowledge. Thank you everyone