Dunlop LA light alloy rims query

[marcos]

I have a question about Dunlop light alloy 27” rims for those who have used them. Are they as difficult to install/remove tires as one online site mentions? Are there indeed pre-war examples as one ebay online seller currently has a 40/32 set? Or did the LA only come available post-war? The online set interestingly has oval Dunlop decals but the listing does not show engravings on the rims…..could this be a first iteration of these rims?

I am contemplating this for my 1951 Raleigh Clubman which I have gradually moved toward everything period correct. Currently it has Velo Orange PBP 700c rims (nice but don’t look right)

 

[Schwinn Sales West]

I have a question about Dunlop light alloy 27” rims for those who have used them. Are they as difficult to install/remove tires as one online site mentions? Are there indeed pre-war examples as one ebay online seller currently has a 40/32 set? Or did the LA only come available post-war? The online set interestingly has oval Dunlop decals but the listing does not show engravings on the rims…..could this be a first iteration of these rims?

I am contemplating this for my 1951 Raleigh Clubman which I have gradually moved toward everything period correct. Currently it has Velo Orange PBP 700c rims (nice but don’t look right)

I have used Dunlop Alloy rims back in the 1950’s. I have used both 26”, and 27” sizes. My take is that they had a very shallow drop center which could contribute to some difficulty in tire mounting. They are also a very soft alloy without much side to side stiffness like a more modern rim extrusion. That said, they were still state of the art and considered a premium rim at the time. John

 

[marcos]

One more question for Schwinn Sales West and SirMike1983....so i ended up getting Dunlop special lightweights instead thanks to a helpful CABEr.....if y'all use rim washers for strength does doing so also add 1mm? to the ERD measurement? .....Which EDD spoke calc says is 623 for the 27" btw

 

[SirMike1983]

Rim washers effectively lengthen the ERD slightly. I would estimate ERD increases 1 to 2mm for full thickness washers as were used on the old rims back in the day. There may be some new, ultra-thin/light washers out there that do not increase ERD quite as much, but I usually work with traditional components when using traditional rims.

You may also need to consider brass flange washers if you're using new spokes on an old hub, especially an old aluminum alloy hub.

 

[Schwinny]

Hey @marcos,
Those are dimpled. No washers. The nipple heads must seat in the dimples. If you are using a supplied ERD number it needs to be from the dimpled version.
You can check it yourself....

The homespun method for figuring rim ERD.
Courtesy - Sheldon Brown
You take two spokes and nipples. Measure the spokes in millimeters and write down the measurement for each. Spokes are measured from the end of the threaded end to the inside of the hook. Thread the nipples on to the spokes to a depth about 2mm below the top. The top actually being the bottom of the screwdriver slot.
With the rim flat on the floor, insert these spokes hooked-end-first into any rim holes exactly opposite each other
The hooked ends will be facing each other in the middle of the rim. Pulling the spokes toward each other, seating the nipples in their dimple pockets. You then take a caliper and measure the distance between the spokes. Caliper arms on the inside of each hook, you tighten the caliper, pulling the spokes, making sure the nipples are seated on both sides. Write down the caliper measurement.
Add the three written down numbers together. If it's an odd number add one making it an even number.
This is the ERD number to use in a spoke calculator. I use the DT Swiss one.

If using Stainless spokes, double butted is the way to go. Good and strong and a little lighter. There are a couple guys on eBay that make custom length dbl butted SS spokes with nips for about $80 for both wheels.

 

[Schwinn Sales West]

Building a good strong long-lasting wheel requires many small, detailed steps. Using old vintage parts (like we do) requires even more attention to the small details. IMO, all of the steps are important, but one that sticks out in my mind is the fitment of the spokes into the hub flanges. The first place any wheel fails is with spoke fatigue at the bend in the spoke head to the spoke hole in the hub flange. On a dished rear wheel you can count on one of the driving, right side spokes to be the first spoke failing. So, we want to do everything possible to make the spoke head to the hub fit a nice radius without any additional stress on the spoke bend. I have seen some old "steel" hub flanges that might require a spoke washer to take up some extra distance, but this problem is far and few between. The more common fitment problem is the opposite where the alloy hub flange is "too thick" and the spoke head will not lay down easily making a 90 degree bend to the hub flange. Campagnolo Record hubs and Robergel spokes were the worst. As a dealer we built lots of pro level wheels. And would radius the spoke holes in brand new hubs to allow the new spokes to seat into the hub spoke holes without bending the spoke heads. You might ask why did the hub manufacturer not take care of this hole shape problem? The hub manufacturer has no idea what brand of spokes, or gauge of spokes you will be using for your build. It's better for you that they left the extra material so you can hand fit the parts depending on your selection of parts.

Have you ever built a new wheel and taken the bike for a ride and heard the new spokes popping and snapping it's because you did not fully prestress and seat the spokes into the hub flanges and the nipples into the rim. Prestressing the wheel "while you're truing it" is one of the little detail steps taken by a pro wheel builder. You true the wheel, remove it from your truing stand, lay it on your work bench and grab "pairs of spokes" and squeeze and stress them pulling the heads into the hub flanges and the nipples into the rim holes. Flip the wheel over and do the other side. Then with the hub axle supported on the work bench push down on the two sides of the rim. Repeat this step four or five different places around the rim. Do this on both sides and place the wheel back into the truing stand for further truing and tensioning. You will need to do this step a couple of times. The wheel is not fully trued until it has been fully tensioned AND it is correctly centered over the lock nuts.

John