FreeSpoke; Surly Marge Lite to Shimano FH-M475, for Pugsley


Edit: Spoke hole offset is +/- 12.5mm on Surly Marge Lite rims.

The rim and tires came in the mail from Surly and the hub was sourced from The Garage in Helena, MT; the spokes were cut at the Summit Bike Shop in Bozeman and a truing stand was arranged via Craigslist.  FreeSpoke provides the spoke length calculation and the graphic assurance that I have put all my pluses and minuses in the right place.

Rim: Surly Marge Lite

ERD: 543.5mm

Spoke bed offset: -6mm, +6mm

Hub: Shimano FH-M475

Center-to-flange: L 33.5mm, R 20.5mm

Flange circle diameter: 61mm, both sides

Spoke hole diameter: 2.5mm

Hub offset: 17.5mm

Spokes: 32

Lacing pattern: 3 cross

Left Right
Spoke length 261.3mm 262.3mm
Bracing angle 4.8°
Tension distribution 100% 69%
Spoke head clearance 2.61 mm 2.61 mm

FreeSpoke is my preferred spoke calculator.  The graphic description helps ensure you’ve input all the proper dimensions, especially when offset hubs and rims are involved such as with the Pugsley.  The above calculation is for a Surly Marge Lite rim built to a Shimano FH-M475 rear hub, for Surly Pugsley.  The dimensions of the Deore and XT high-flange models appear to be the same as the M475.

For this build I used 262mm spokes all around.  Some Rock-n-Roll Nipple Cream was applied to the threads, while the spoke holes and nipples were generously greased to prevent corrosion in use and to reduce friction during tensioning.  This is the first time I’ve used a commercial spoke prep. Linseed oil is messy, and does too little to minimize friction and wind-up during tensioning in my experience.  The Rock-N-Roll prep is less messy than linseed oil and was easier to work with during the build.  I’ve had success building wheels with standard bearing grease, and wouldn’t hesitate to do it again.  With proper spoke tension, I’ve never had any spokes loosen in use.

In a day, I sourced all the necessary parts, laced the spokes, tensioned and dished the wheel, and installed a new pair of lightweight Surly Larry 120tpi tires.  In a day, the metamorphosis is complete– my wheels are lighter, yet more voluminous than they were yesterday.












My rear Schwalbe Big Apple developed a slow leak in the last two days of use, and a shred of steel was found when the tire change took place.  Technically, I managed to ride from Anchorage, AK to Bozeman, MT without a flat, a distance of over 3200 miles.  To dish the new wheel properly, I installed it in the frame several times and used my fingers to estimate the distance from the chain stays.  About 2000 miles since Whitehorse, my second chain on this cassette is worn.  The time has come to return to 8 speed equipment, easier shifting and cheaper parts.  Check the manufacture date on the Marge Lite rim– it’s Cinqo de Mayo.

Image, calculated figures and format courtesy of FreeSpoke.

8 thoughts on “FreeSpoke; Surly Marge Lite to Shimano FH-M475, for Pugsley

  1. Nick – glad you managed to get everything sorted for the build. For my curiosity – did you measure your Marge Lite to get the spoke bed offsets? It’s just that others have used -12.5 and 12.5mm. Not that it makes any difference to 262mm spokes being the correct spokes… I have a Rolling Darryl turning up tomorrow to build up, so have speculated with Freespoke myself a bit lately as well.

    • Hey Tom, I’ve wrestled with the issue before, trying to wrap my head around the FreeSpoke system. I’ve always wanted to use -12/+12 for the offset of such rims, describing the spoke hole location on an absolute scale. I have seen others input a 12mm offset as -6/+6, so I’ve taken this approach although it may be fallacious. As you say, it doesn’t significantly change the spoke length calculation, but I’d like to get to the bottom of this. Let me know if you come up with any definitive answers. Nobody else on the web seems to have the answer, so we can help demystify FreeSpoke for others.

      Do you have a Mukluk or Pugsley? How about that new beast, Krampus?


      • Nicholas – I’m about to build wheels for an off-set rear frame similar to a Pugsley that will be used to ride the Canning Stock Route next year (with Joe Cruz, Scott Felter and my wife).

        Vik (Lazy Rando) did a post a while back critiquing various builds using Freespoke and brought up the very -6/6 vs -12.5/12.5 conundrum you mention. He concluded that the -12.5/12.5 spoke hole offset was the correct one. If you plug a Rolling Darryl into the ‘bench’ via the rim database in Freespoke this is what it comes up with. The measurement for Marge Lites are incomplete in Freespoke at the moment as the guy’s not had a chance to measure one, but are supposed to be the same.

        I’ll let you know in a few days time when I’ve built my wheels.


    • I did not measure the Marge Lite, but used available data from Surly. The spoke hole is definitely about 12mm from center, but it is the way FreeSpoke handles these numbers that confuses me.

      • Good to know, as that’s what has seemed logical from the beginning. I was thrown off track by a bandwagon of misinformation. I’ll correct the above calculations and link to Vik’s explanation.

        Is it a 9zero7 or a local builder?

        Canning Stock Road looks awesome! It’s fun to imagine bike trips with bigger tires; much of the promise that early mountain bikes gave us is reborn in the new fat tire wave.

  2. hi there, a while ago you were experimenting with 29er wheels in the pugsley, and you used a non offset rim (i think). i was looking into using 29er wheels in the pugsley, but when rresearched it seemed offset rims were required to get enough spoke tension. how did you deal with this problem.

    • There aren’t any offset 29er rims available, so far as I can tell. There used to be a few from Bontrager, but are now out of production. The Snowcat rims are 44mm wide and drilked offcenter and would make a psudo-Krampus (Krampus is the new demi-fat 29er). As well, the new 50mm 29″ rim from Surly, called the Rabbit Hole, is offset drilled like Marge Lite.

      I used a Salaa Semi-Disc 29er rim without any issues. There is definitely more tension on the non-drive side, but it works. The SRAM 406, 506, and X7 hubs have a taller non-drive flange (unlike typical hi-lo hubs which are taller on the drive-side) which alleviates the uneven distribution of tension.

      What kind of riding do you plan on the 29″ wheels? Tires?


  3. Nicholas – a Colorado builder (Twenty2 Cycles) as I couldn’t find an Australian one who’d be on for it.

    The Canning Stock Route is going to be the ultimate remote camping trip with lots of grunting and cursing in between 🙂


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