OndrejP_SK

Hi,

I'm about to build a wheel using Nexus Inter8 "red label" (SG-8R36) hub and Mach1 "270" rim. 36 spokes. The 270 rim has no offset in the spoke holes i.e. all holes are in line.

I already have a Nexus Inter7 (SG-7C21) with this identical rim laced 3x, but the angle at which the spokes enter the nipples doesn't seem good to me - I'm worried thet it is creating a stress point and that the spokes will eventualy break in the first thread. I've only done 500km on it so far and no broken spokes yet [:knocks on wood:].

The Inter8 that I'm about to lace has even higher flanges than the old Inter7.

Do you think 2x pattern would be strong enough to transfer the torque ? What about the hub flanges - would they withstand this type of load ?

How many of you are using 3x ? What is your experience ? Anyone using 2x pattern with this hub ?

Thanks in advance.

AEO

both spoke exit angles look fine. As long as they are not crossing over another spoke hole, there is no reason to use a lower cross number.

pat5319

X3 best

Retro Grouch 

1. Run the wheelbuild through Spokecalc. That has a column which recommends the optimum number of crosses.

2. I have an acquaintance who owns a Bike Friday triple with 20" wheels and a SRAM 3X7 rear hub. They were constantly breaking spokes at the nipple. After having the 3 cross rear wheel replaced once by Bike Friday and rebuilt once by another wheel builder, they brought it to me. I rebuilt the wheel 2 cross to reduce the angle at the nipple/rim interface and solved the problem. YMMV.

fietsbob

In 32 hole, as they are, Rohloff specifies 2 cross, except smaller wheels,
on a 20" rim they say use a 1 cross.

that is what they used building up my Bike Friday with that hub.

Jeff Wills

I think he's concerned with the angle of the spoke at the rim. And he's right- a 3X build on a small rim (but he doesn't say what size wheel he's building) and large can bend the spoke severely after it exits the nipple if the spoke hole on the rim is a tight fit.

If that is the case, a 2X build would work fine. Internal gear hubs make for symmetrical wheels, providing for plenty of reserve strength. As long as the spokes are properly tensioned it won't have a problem with transmitting torque.

FBinNY 

With 36 holes a 2x will be comparable to halfway between 2x and 3x on a 32. All in all, won't be an issue.

When making cross decisions on extra large flange hubs, consider the radial distance from center to the spoke's line of action. That's what determines the torque transfer characteristics. Often you'll find that a 2x on a large hub will have a longer lever arm than a full tangent (36h 4s) on a typical small flange road hub. If pros can climb the Alps with 3x 32h on a SF hub, then you shouldn't have any problems with reducing the cross on your larger hub.

Another consideration is how far off radial the spoke leaves the rim, which is what the OP seems concerned with. While I've never had an issue with spokes passing 2" off the axle (radial) I don't like to go much more than that and usually reduce crosses when building with flanges of over 4.5" in diameter.

krome

He's got 606mm ERD in the calculator screen shot. Should be fine as a 3x wheel. I've done 3x in a 507 (24" MTB) rim (with a Nexus 8 Red band).

dbg

I've owned many of these and rebuilt them all numerous times. I settled on 2x as my favorite for these IGH's. I'll add a pic of the most recent build (2 days ago) on a 650B rim with 2x lacing when I get home.

OndrejP_SK

Yes, it's a 700c rim.

I'm worried by the angle of spoke leaving the nipple with 3x lacing, but also by the less tangential angle at the hub with 2x lacing. And yes, the nipples are quite tight in the single eyelets of the rim.

I've settled on this rim because it's cheap (14€) and it's 17x700c - something in between road bike 14-15mm rims width and trekking/MTB 19mm rims. I plan to use 32mm wide tires. Maybe I should rethink the rim choice ? But unfortunately there are not many 17mm rims available here and going to 19mm width seems too much.

This Inter8 is 92mm which is a little under 4''

dbg

Posting promised pics

dbg

You'll also notice these are into track drops (120mm). I had to modify the axle slightly and remove some left side housings (and use a OC rim to get it back to center without large dish issues) but it turned out great.

Bob Pringle

OP-

What's that spoke pattern calculator? It looks like a real handy tool!

Bob P.

OndrejP_SK

David: Thanks for the images.

Bob: the tool is called Wheel Calc https://www.machinehead-software.co.u...alculator.html

I would really much prefer to use 2x. Now the question is: will the Nexus hub like the 2x lacing pattern ? I'm a little worried about the risk of cracking flange.

Is there anyone with a Nexus hub laced 2x to a 26" or 700c (or similar size) rim ? I'd be calmer if I knew that someone has already tried it and could provide some info on long-term reliability.


BTW: in the attached image is my current wheel: Nexus Inter7 SG-7C21 laced 3x to Mach1 270 (700c size) rim - the reason I started this whole thread

FBinNY 

You can relax. 2x is a very common pattern for Nexus hubs, and if there were any danger to the flanges you'd see reference it it voiding the warranty, the way some companies void warranties for radial lacing.

dbg

I have current nexus hubs laced to 26" and 650B --all 2X. The current 650B was previously on a 700C for 3 years. My 26's have been reliable "indestructo" bikes for many years. I even had one on a 20" wheel for a while.

dbg

Forgot to mention.. I had a conversation with Sheldon Brown (several years ago) about using nexus 7's for tandems. He thought they would be just fine doing duty on a tandem. I also had an aging shimano IGH 4-speed which he advised against putting on a tandem. I still use that 4-speed today on my commuter bike --all winter long, 8 inches of snow, -20F, --rock solid. And I did put one of my 7 speed nexus IGH's on a tandem (and gave it to a friend as his sunday cruiser in Pewaukee WI).

OndrejP_SK

I just realized that the angle of spoke entering the nipple depends also on the offset of the holes from the center of the rim.

(The following calculation is valid if the spoke leaves the hub exactly tangential.)

a) If the nipple is pointing at the center of the hub (all holes along the center line of the rim, no offset), the distance between the ideal and actual point where the spoke attaches to the hub is 54mm. (diagonal of a rectangle where one side is 1/2 of the effective flange diameter and the other side is the flange offset from the center plane of the hub)

b) If the nipple is pointing at the flange (rim with offset holes), the distance between ideal and actual point where the spoke attaches to the hub is 46mm. (1/2 of the effective flange diameter)

Now it seems I have 2 options: use 2x lacing pattern with the original "Mach1 270" rim, or find a rim with offset holes and use 3x lacing. Or both

OndrejP_SK

I've decided to use 2x pattern AND a different rim because of the offset holes. The rim is Mach1 210, it's 30grams heavier and 2mm wider (25mm outside width) but it has the offset holes.

The resulting wheel looks like this:
- there doesn't seem to be a significant bend at the spokes exiting the nipples
- the angle of spokes at the hub seems to be just fine
- the "lever arm" is still about 3cm - as FBinNY wrote it's still more than most standard road hubs.

Thank you all for advice.