kevistopheles

First time and I am taking this slowly (and viewing it as a learning experience). I have a CR-18 26 x 1 3/8 rim for my 73 Sport that I am going to put a Sturmey Archer X-FDD (dynamo+drum brake combo) on. I know that will involve some fork spreading but right now I am just interested in getting the wheel built.

I used a spoke calculator online and I come up with 270.5 for the length (the SA hub accepts 13 or 14 gauge spokes. As I understand it, I need to round down 2mm when I buy the spokes. of course there is no 270.5 spoke length (or 268.5 for that matter). So do I round down and then go to the nearest size? Is that correct?

Michael Angelo 

You round up to the next length.

Michael Angelo 

Make sure you measured the hub an rim correctly, it can be an expensive mistake.

kevistopheles

Thank you...I got the ERD from

https://wheelbuilder.jmoore.me/rim/print

They happen to have an entry for my exact wheel. That said, I probably should measure to make sure. Thanks for the heads up.

Bill Kapaun

Why not post your numbers for the rest of us to look at.
I can't find offsets & diameters for that hub.

I built a pair of 36 spoke CR-18's in 27" last Winter.
I would have gotten spokes that were about 1.0 to 1.5mm over calculated values if I were to do it again.

On a double wall rim, you have a bit to play with if the spoke ends up a bit long. There aren't any tube puncturing issues.

ThermionicScott 

Do that. They can vary.

noglider 

Great ideas for that wheel. You'll love it.

I have an X-FD (no dynamo) and wish I had gotten yours. I put the hub on my Raleigh Twenty, which badly needed a good front brake. I love the fact that a drum brake doesn't give a hoot about rain or snow.

73emgee

I recently went through this but is was for a AW hub and front Dynohub. When I measured the CR-18's, I came up with a ERD of 578mm. With this measurement and those off the hubs the spoke calculations and the spokes I ordered were a perfect length, with good thread engagement and no spoke protrusion. You can see more info on the "Rims and Spokes" post on the below blog.

kevistopheles

I just ordered the hub (the X-FDD). As far as the hub dimensions...until I have the hub in hand to measure here is what I have...



FWIW When I use the spoke calculator HERE I get a spoke length of 272.9. I need to measure the wheel tonight to double check because that was using an ERD of 580 for that rim listed HERE.

kevistopheles

BTW...thank you Auchencrow for the tip on spokes.

smallpox champ

I recently built a wheelset with the same rims and averaged the length by using a couple different calculators. I purchased my spokes from here:
https://www.danscomp.com/products-PAR...14G_Spoke.html
Only $0.25 and cut to length.

Also I used an ERD of 578 for the CR-18.

kevistopheles

I'm gonna see if I have a metric ruler around here somewhere (I'm pretty sure I do) and get that rim measured. So if I recall I need to pull tow spokes form the old wheel out (with nipples) insert them opposite of one another and measure the distance between the nipples (and add in the length of the nipples).

I'd better get cracking.

Bill Kapaun

Assuming cross 3, I'd order 271.

zukahn1 

This seems about right since 271 14 guage would a standard replacement spoke for most 26 1 3/8 wheels.

kevistopheles

So I just need a little clarification here. I have seen some folks say round UP to the next size and some round down. Since the spoke calculator came up with 272.9 and I would be inclined to think spokes that are too long would be a problem at the nipple end I was leaning toward 272. That said, if 271 is better then I can do that. Don't see why it would be a negative.

At present I am planning 14g DB spokes 271mm

kevistopheles

BTW, the ERD as measured (three times) was exactly 580 on the CR-18

Bill Kapaun

I used the numbers you provided with an ERD of 578.
Spocalc came up with 269.7.

Personal experience using the Sun CR-18's (and Sun CRT 16 II's & M13 II's) would cause me to round up the 1.3mm
I would much rather insure the spoke end reached the bottom of the screwdriver slot of the nipple than be short at all. (short results in a weaker joint)
You still have 2+ mm of thread left before you are flush with the end of the nipple.
Even if it protrudes a bit, it's a non issue with a double wall rim, as long as you don't run out of threads.

I've used Suns published ERD's, so maybe that's where my extra mm comes in?
IF you've carefully measured, I can't argue with your results.
You did measure to the bottom of the slot????

BTW, since this is a drum brake wheel (I'm assuming powerful braking) I'd go to a 14/15 double butted spoke to help absorb the stresses. The thinner middle section "stretches" a bit, resulting in less flex in the bend. Less fatigue over the life of the wheel.

kevistopheles

I measured from the bottom of the nipple to bottom of the nipple (260mm) then added the length of nipples in (they were 10mm each). i measured it three times in three different locations on the wheel.

kevistopheles

Okay then, spokes and nipples ordered, the SA X-FDD arrived today and the rim is just sitting against the closet door in my office. I have been planning to use the upturned bike (I have a few frames I could use) for the truing stand but I was wondering if it makes sense to pick one up or make one. I looked at the park TS25 that attached to the Park bike stands (I have an old Park PCS-1 that it will fit on). At around $35 it's cheap and I have the stand it can fit on. Another thought was to got to the community bike shop and see if I can grab an old fork and use that. I could secure it in my Workmate. Then there are a number of DIY truing stand designs out there like the Roger Musson one but I don't know that it's much better than buying a cheap stand like the SunLite (around $50).

Any thoughts?

noglider 

No truing stand is necessary, but they're nice. Set your budget according to that. I have a ts-2, but it's packed away during our pending house move, so I built a wheel with my bike as the stand last week. No biggie. But yeah, I love my ts-2.

kevistopheles

Good point, The main reason I am thinking of one is because I live in a spot where weather isn't exactly cooperative and I don't have may work spaces in my house (no garage or basement) so a way to set something up on my dining room table would be helpful. Then again if the weather holds up the back patio is great.

A TS-2 would be cool. Out of budget but cool.

noglider 

I got lucky with the TS-2. Someone offered me a deal I couldn't refuse. I wouldn't have bought it otherwise.

kevistopheles

Yeah, it's those "deals" that always get me in trouble.

kevistopheles

So after a lot of thought and looking at nearly every DIY truing stand option (including the Roger Musson design) I decided that I was going to purchase one. I am pretty handy with some things. I can dig into my car and fix it. I can pull apart a camera and do simple service. I can open up my computers and fix them. I'm even pretty good at simple wiring but basic carpentry eludes amd and I realized that trying to build a truing stand was one of those things where I really WANT to do it but it'll never happen, and if it does it'll be a disaster.

I looked around and it became clear that the Park TS2.2 was a really great stand and I couldn't afford it. The rest of the stands pretty much all fell together in one huge lump. After reading a lot of reviews, comments and looking at all the stands that were within my budget I decided on the Feedback Sports Truing Station, I was also to go check one out in person at a LBS (well within a 100 miles) and it felt like something I could be happy with. I know it's not a "profession tool" and I also know it is not "necessary" but it will allow me some added convenience that using the upturned bike wouldn't so it was worth it to me. I am also a believer that the user makes the tool not the other way around.

I'll report back on what I think of it after I've had some time with it.

Also, I think it's pretty funny that folks point to the Roger Musson truing stand when you talk about DIY stands because he in fact did not build those himself (according to his book) he had a cabinet maker friend make them and while I'm sure a number of you may have the ability to make something like that there is no way I could pull it off.

noglider 

It's a funny thing. The top pro tool is great to have if it's cost justified, which is funny, given that you can do entirely without any stand.

chances are you'll like the one you're about to buy.