Wednesday, July 24, 2013

Rims and Spokes

Now that the hubs are rebuilt I'm ready to starting lacing up some new wheels for the 1953 Sports.  The original 26 x 1-3/8" Raleigh Patent Rims which are commonly referred to as Westrick rims were rusted beyond use.  Most classic three speeds use a Westwood; Endrick; or Westrick type rim.

Westwood rim, these are intended to be used with rod-brakes, the brake pads bear against the raised center section.  They do not have side faces for caliper type brakes.
Endrick rim, these can only be used with caliper type brakes, there is no raised center section they can not be used with rod-brakes


Raleigh Patent rims, A.K.A. Westrick, these are a cross between Westwood and Endrick rims.  They have a raised center section so rod-brakes can be used as in this picture.  You can also see they have a side face for caliper type brakes.

That ugly sticker just peels off

I will be replacing the rusted steel "Westrick" rims with Sun CR-18 alloy rims.  If you want to maintain complete originality replacement Westrick rims are usually easy to find.  I wanted to try these rims for their lightness and better braking, especially when wet.  When ordering new rims you must know the Bead Seat Diameter (BSD) of the rim.  For many classic three speeds using 26 x 1-3/8" tires this is 590mm (sometimes is referred to as 650A), but be careful there are some that have a BSD of 597mm.  The 1953 Raleigh Sport rim is 590mm.

I've also decided to use new spokes with the CR-18 rims.  When building wheels with new rims and spokes you also need to know the Effective Rim Diameter (ERD) of the new rim in order to calculate the proper spoke length for the wheel.  There are several ways to measure ERD, search on-line and find one you are comfortable with, most rim manufactures also publish this dimension, I prefer to measure it using the actual rim I'm building with.  I measured the original Westrick rims to have a ERD of 576mm, and the new CR-18 rims measured 578mm.  In this case there is very little difference between the two so the original spokes would  have been useable assuming I used the same number of spoke crossings.  There is an advantage to using the old spokes if you can because they are a better fit with the thin flanges used on the Sturmey-Archer (SA) hubs.  Modern spokes are designed for thicker hub flanges.  If you use modern spokes in the thin flanges of  a SA hub, you will need to use spoke washers to take up the extra space under the spoke head.

In addition to the ERD, most on-line spoke length calculators require measuring the diameter of the spoke hole circle on each flange, flange spacing center to center, number of spokes, and the number of spoke crossing you will be using, (2X, 3X, 4X, etc.).  I made a simple stand from a scrape piece of 2 x 4 and metal plate, with a 13/32" hole drilled, so the hub can stand upright on its locknut to facilitate obtaining hub measurements.



After you obtain your rim and hub measurements find a on-line spoke calculator you like and enter the input values, I usually use this one www.wheelpro.co.uk/spokecalc .  In my case using a CR-18 rim, 3X crossing, and a 40 hole AW hub, with 12mm spoke nipples, the spoke length calculated was 272.2 mm for the left flange, and 271.7 for the right.  I rounded these to 272mm and ordered 40 272mm spokes.  The spoke length for the front Dynohub using 3x crossing on left flange (small), and 2x crossing on the Dyno side (large flange) and a 32 hole hub, the length calculated was 282.8mm for the left, and 256.3mm for the right.  I rounded the left to 282mm (only even size lengths available), and the right side to 256mm.  I ordered 18, 282mm, and 18, 256mm spokes for the Dynohub.

Once the spokes and nipples are received I can start building the new wheels for the 1953 Sports.  There are many on-line sources for information on wheel building, find one your comfortable with and start lacing.

Please share your thoughts and experiences.

3 comments:

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  2. Do the cr18 rims work with Rod Brakes or just calipers?
    Westrick rims are hard to come by, and I'd prefer alloy rims to steel. An old Raleigh DL1 with rusted Westricks is in need of a new braking surface!

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    1. The CR18 rims do not have a raised middle section needed for rod brakes, I don't think they would work. The CR18 rims I have are 26", I believe the DL1 has 28" rims.

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