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

4068WP

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.

4047WP

4051WP

4061WP

4055WP

4069WP

4082WP

4113WP

4096WP

4140WP

4139WP

4142WP

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.