Positron400

Hi,

i recently got my hands on a Shimano FH-6361 rear hub. (https://velobase.com/ViewComponent.a...m=110&AbsPos=7) I want to build up a new rear wheel, but the flange is different to what i know and i am unsure as to how to go a about spoke patterns. I presume a 3 cross is intended (36 hole hub), but the drillings are weird.

Does anyone have experience with this hub?

KR
P!

Andrew R Stewart 

IIRC the AX and a year or three's Dura Ace as well had flanges scalloped on every other spoke hole in a manor that allowed all the spokes to exit the flanges in the same direction (elbows out, heads in I think). The rest of the spoking pattern was the common 3x with interlacing. Shimano's thought was that with the elbow on the flange's outside there's more spoke to flange contact and spoke breakage at the elbow would be less frequent.

Before sinking too much time and effort into this hub do the homework on the cassette fit and the freehub body's attachment to the shell. IIRC, again, these hubs used twist tooth, SIS, cassettes w/ the last cog threaded and possibly the old FHB interface. Modding these hubs to fit current cassettes might not be possible. Andy

Positron400

thanks. So it's just a matter of heads and ellbow orientation. That should be a non-issue. I appreciate the input regarding the hub. I am aware that the spline pattern is different to the HG and the last cog is a thread-on, but that's fine I'll just file down the splines to fit the freehub of a current 7speed.

KCT1986

Here is how the spoking looks with these hubs, all spokes head in.

Since the spokes are paired at the hub, a small adjustment to spoke length calculation may need to be made, (never used these so just a guess).

Positron400

I was wondering about the spoke lengths - when you say, you never used those calculators, how did you do it then? calculate them yourself? (if so, mighty impressive)

KCT1986

Another unusual 'feature' of this design was the spoke drilling was angled for the specific direction of the spokes.

Positron400

holy moly - this should be an interesting wheelbuild..

Andrew R Stewart 

Actually no real difference but for the direction of inserting the second set of spokes into the flange. Do the scalloped holes first. The second flange's spokes are not interacting with flange 1's spokes so it laces up faster than a "normal" wheel would.

I always thought the scallops should have radiated the other way so the outer set of spokes are the pushing ones, not the pulling ones. Andy

Jeff Wills

BITD, many repair manuals had charts of different hub/rim combinations. You’d look up what you had, figure out how many cross, and grab the right length spokes. If it was some unknown combination, you measured things and did the calculations on paper- basic trig is all you need.

KCT1986

Sorry for the confusion, when I said that I never used them, I meant 'never build with them' (or even owned one). Had seen these on ebay, and did some research, but never purchased. Opted for a newer version, with a more common type of freehub attachment design.

The pic of the laced hub posted earlier is from a Shimano catalog showing the design. Attached is other catalog info, probably referring to the possible increase in strength with the 'all elbow out' lacing.



My comment about spoke length was just a thought that occurred to me when looking at the drilling angle & placement. Never had one in hand to determine if it mattered enough to be a concern.

Jeff Wills

I had a Dura-Ace AX rear hub years ago. I can’t recall doing anything unusual with the spoke lengths and it came together just fine.

Of course that was some time in the last millennium. Things were different then.

wheelreason

AX is how I know engineers get high...

Positron400

I actually really like the design and colour scheme of the hubs. Really the whole groupset sans the water bottle

sd5782 

Regarding the freehub, you will still need a threaded small Uniglide sprocket to hold the hyperglide sprockets in place.

Positron400

Yes, thanks I was aware of that issue.

jsallen

Calculating spoke length: the spokes need to be longer, as the holes from which they cross are farther apart. Measure spacing between more distant and closer adjacent spoke holes. Call the smaller spacing a and the larger one b. The spacing to the second hole is a + b, same as it would be with evenly-spaced holes. The difference between even spacing between two adjacent holes and b is
b - (a + b)/2
and half that is added to the length of each of the two spokes pulling in opposite directions:
b/2 - (a + b)/4
or
(2b - a - b)/4
which reduces to
(b - a)/4
Add this to the length you would calculate with evenly-spaced holes. This is approximate, as it assumes that the spokes leave the hub tangentially, but for the small differences in length here, it is close enough. If you want to get fancy about it, multiply by the cosine of the angle at which the spokes leave the flange, relative to tangent to the flange. This would be necessary with a low cross number.