Wheel building input (27.5 with IGH)

[mrpelican]

I'm working on a BBS02 conversion for a 2017 Salsa Fargo, to be a commuter and medium duty cargo bike. At some point when it is farther along I will document more of what I end up doing with it, since I haven't seen many mentions online of converting this bike.

For now, I'm getting ready to build a rear wheel with a Shimano Alfine 8-speed hub. I have the SG-S7001-8 with 36 holes. I got the 36H version thinking it would be a good choice to make the wheel stronger. I've also decided on 27.5" wheels for a couple of reasons, and I have some 50mm road/gravel tires that I think will work well (Donnelly Strada USH). The combination of those 3 choices has severely limited my rim options, so if I were to go back in time, I'd probably order the 32H version. Here is my plan for the wheel build for now:

Velocity Cliffhanger 27.5, 36H rim (25mm inner width)
triple butted spokes (13/15/14 gauge)
+3.5mm frame offset, via dropout spacing adapters

This rim seems like the best match for the tire size I'm using (and considering I may go wider in the future). The other option is Velo Orange Voyager, but that is a bit narrower and too shiny. Unfortunately the Cliffhanger is on backorder right now, so I may just have to wait. Other rim suggestions are welcome, though I doubt there are a lot more options out there.

Putting this into a spoke length calculator seems to give acceptable results, though I haven't done this before. (https://kstoerz.com/freespoke/?link=...n=36&xL=2&xR=2) As far as I know, the wrap angle at the rim just needs to be less than 8 degrees, which it is, but it's getting close.

Any suggestions are welcome, especially if you notice any red flags.

The frame offset is mainly to help the chainline, but it also happens to eliminate the wheel dishing, which is nice. I may practice by building another wheel with spare parts I have, before starting to lace this one.



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[73Eldo]

I'm not an expert, used to build a lot of wheels back in the day and only a couple recently but the thing that jumps out at me is a 2 cross? 3 is kinda the standard unless you have some special theory or aspect you are going for.

A good way to practice is to undo and redo an existing wheel. At least that way you know it all works together and how it should come out. Starting from scratch you can make mistakes in the design and the process and it can be hard to tell where you went wrong.

[mrpelican]

I tried 3 cross in the calculator as well. It came out okay, but the angle between the spokes and rim was a little lower with 2 cross. The guy that made that calculator also had a note for that hub that he recommends 2 cross with it.

[73Eldo]

Interesting. I didn't think those were too big especially on a 27.5. I think Grin has some videos talking about building wheels with hub motors which can get pretty big so conventional lacing rules kinda don't apply.

[ncmired]

For hub shells as big around as the Alfine, I suggest three-cross lacing for narrow/low and directionally drilled 700C rims (like those from Ryde), two-cross for 650B/27.5 or 26 inch, and one-cross for 20 inch - especially for the taller/wider rims, like those from Velocity.

Rohloff and Enviolo both recommend two-cross lacing max, and no radial spoking.

I can't write much on rim brands, but I have and like rims from Velocity, Halo, and Ryde.

[73Eldo]

Here is the link to that part of Grin's site. I don't remember if its in the text or videos but I think I saw them go into depth about the pros and cons of the different options and I think they have their own spoke calculator that is optimized for hub motors which tend to be pretty large. I think they also have some how to build a wheel videos.

https://ebikes.ca/learn/wheel-build.html

[ncmired]

It's hard to see, but my Marrakesh has 650B Cliffhanger rims, laced 3-cross in the front (36 spoke Velo Orange disc hub) and 2-cross in the back (36 spoke Alfine SG-S501 hub). The spoke-to-rim angles for the quad spoke sets are almost identical front to rear and are "comfortable".

Contrast this to the 3-cross (both front and rear) laced wheels on my Scapegoat, with 650B Dually rims (32 spokes, Surly front, Rohloff rear), with a pretty severe outside quad set spoke angle on the rear wheel. This bike was purchased pre-built. I'll rebuild the rear wheel, well, someday.

My Evasion has 3/2-crossed Blunt 26" rims, 32 spokes, White Industries and Alfine hubs, and "ok" angles.

MY natural inclination would have been to choose 3-cross, too. That was until the Scapegoat came in, and I was checking the spokes. Then I started reading and heeding what the IGH hub vendors had to say.

Hell, I'm just an amateur and occasional wheel builder. But, don't expect experienced builders to do it right either, based on some pictures I've seen. Maybe their IGH wheel build request volume is low.

[mrpelican]

I read somewhere, probably on Sheldon Brown's site, that there are spoke nipples with a more spherical head shape. They are supposed to keep things stronger when the spoke-rim angle is a little higher. I may use those for my rear wheel since it is going to have angles that are on the upper end of acceptability.

example: https://wheelbuilder.com/sapim-brass-polyax-nipples/

[Arboh]

Id like to know about the fitment of the BBS02 into the Fargo frame. Any interference with the chainstay? I'm considering putting a BBSHD into the same frame...
Thanks !

[mrpelican]

I'm neck deep into the conversion now actually. It's taking me a while, but it's coming along. I plan to put up a nice build thread when it's finished, but if it would be helpful, I could probably start a work-in-progress build thread and share what I've got so far.

Probably the main thing you'd want to know is that with the BBS02, I need at least 2.5mm of spacers on the bottom bracket for the motor to clear the chainstay. This is with a 2017 size large Fargo, so it may be slightly different with other years or sizes. And it is probably a bit different with the BBSHD, but at least that should give you a reference point. The other thing is that due to the 73mm BB, chainline is not ideal, unless you get one of the Lekkie offset chainrings or something similar. (That, along with the offset wheel build, are needed to get a straight chainline with the IGH I'm using.) For a simpler build, without so many custom parts, I might recommend a bike with a 68mm BB, but this is a cool frame and I think the end result will be good.