Spoke size Rohloff and Rigida Andra 30

[phopwood]

Hi,

I am thinking about building my own back wheel with a Rohloff and Rigida Andra 30.  I would like to know the spoke size, the Rohloff website says 238mm I have no reason to say it is wrong so I guess I would like to know does this match your spoke size.

All the best and thanks.

Peter

[David Simpson]

Yes, 238mm is the correct spoke length for the Andra 30 rims with a Rohloff hub.  I built my own wheels this year for my Nomad Mk2 that I built up myself.  They were the first wheels that I have ever built, and it was fairly straightforward.

I followed the instructions in these excellent books:

• The Professional Guide to Wheel Building, by Roger Musson (http://www.wheelpro.co.uk/wheelbuilding/book.php)
• The Bicycle Wheel, by Jobst Brandt (http://www.amazon.com/The-Bicycle-Wheel-3rd-Edition/dp/0960723668)

Both books are well worth having.

- Dave

[triaesthete]

Hi Peter

you can do the calculations yourself on here http://www.wheelpro.co.uk/spokecalc/ and try here as well as not all calculators give the same results http://spokes-calculator.dtswiss.com/Welcome.aspx?language=en

if you want cost effective wheelbuilding instruction frpm first principles buy the ebook as well http://www.wheelpro.co.uk/wheelbuilding/book.php

unbelievable value for £9 (with practical tips on spoke length choice/compromise amongst other things)

best wishes
Ian

[phopwood]

Many thanks both.  I have only ever built front wheels but I feel that I should be OK with the rolhoff as there is no dish,  I will take a look at the eBook.

Peter.

[David Simpson]

I should have also mentioned that the Rohloff manual has tips for building wheels using the Rohloff hub.

Page 55 explains that the spokes should not cross over the hub cap fixing screws:
    http://www.rohloff.de/uploads/media/2_Monting_En2013_10_web.pdf

Pages 125-126 show how to lace the spokes correctly.  The "European" vs. "French" spoke hole patterns are explained on page 55.
    http://www.rohloff.de/uploads/media/3_Service_En_2013_10_web.pdf

- Dave

[mickeg]

I built a 36H wheel, make sure you are using the right table, 32H or 36H.
http://www.rohloff.de/en/technology/workshop/spoke_lengths/

[David Simpson]

make sure you are using the right table, 32H or 36H

Good point!  I completely forgot about that vital factor in the equation: spoke count.  My wheel (using 238mm spokes) was a 32-spoke wheel.

- Dave

[phopwood]

Yes good point I am looking for 32 spokes.

Peter

[triaesthete]

That's why it's always worth corroborating any advice by using a spoke calculator or two!

Measure thrice and buy spokes once.

If you practice on the calculators it is also possible to get an idea of how quickly the build will gain tension. ie is the Rohloff figure arrived at by rounding up or down from the theoretical length required?

Roger Musson covers all this stuff in the Wheelpro book, and in practice attention to detail at ALL the early stages as far as lacing and pretensioning mean the actual dishing and truing bits that most people fear almost do themselves.

Good prep means the tension goes into the spokes and not the builder. Zen like levels of calm are achievable.
Ian

[phopwood]

I have played with the DT Swiss spoke calculator and you are correct the 238mm is based on 36 spokes and I would need 242mm for 32 spokes.  I plan to go 32 spokes.  I think I will spend a bit more time playing with the calculator.

All the best.

Peter

[triaesthete]

Be careful Peter

DT Swiss and Wheelpro  spoke calcs both suggest 241mm

Based on 100mm flange dia, 60mm flange spacing and a symetrical (ie front typewheel) 2 cross lacing and an erd of 535.9mm on Thorn website. http://www.sjscycles.co.uk/rigida-andra-30-26-%28559%29-mtb-css-rim-black-32-hole-rohloff-drilling-prod13269/

Meanwhile Rohloff suggest  236 mm spokes for any  erd from 534 to 537mm laced 2cross  on 32hole  26" rim.

I would buy the rim and measure the erd myself before purchasing spokes. (I've only built with the Grizzly rim on Rohloff so have no idea if the Thorn erd is accurate or not.)

Ian

[mickeg]

This thread is expanding beyond spoke length.  So, I will add a pitch for this web link that I think is outstanding for novice wheel builders.
http://sheldonbrown.com/wheelbuild.html

My last set of wheels, I used the Rohloff table for spoke length and the data from SJS website for ERD for the Andra 30 rim.  Worked just fine on my 36H wheel.  I listed the link to the Rohloff tables above.  I might have double checked it on a calculator, do not recall.  I did use a calculator for the front wheel, do not know which calculator.

I have three other sets of wheels I have built up over the past decade on other bikes.  In those cases, I brought my hubs and rims into a local bike shop that was willing to do the measurements and calculate the right spoke lengths I needed for no charge since I was buying the spokes from them.  It is an unusual shop that will do that, but there might be other ones out there that can do it for you.

The suggestion above that you buy the rims and measure the ERD, I know that I do not have the tools to measure with any accuracy and precision.

Make sure you are using the right cross pattern in the calculators if you use a calculator instead of the Rohloff table.  Most calculators I have seen have a default value of 3 cross entered.

A final comment on spokes for the Rohloff, that is an unusual length and typical bike shops that do not work with Rohloffs might not stock them.

[triaesthete]

Hi Mick
+1 to Sheldon, he's always my first call for a basic grounding  in any aspect of bike tech.

ERD is easily measured with two spokes two nipples and a ruler. Roger Musson(Wheelpro) tells you how. This is why I like his approach, he suggests you take full responsibility for the whole build, just like you might hope a professional would. No fobbing off responsibilities to shops or forums, they won't be much good to you if your wheels fail underneath you 

As for spoke length you know you are getting good when you can cope with disparate values from different calculators and sources, and allow for rounding to the nearest 2mm on spoke length, and still get really evenly tensioned wheels with all the spoke heads flush with the bottom of the screwdriver slots in the nipples 

I have an unconfirmed suspicion/theory that spoke breakages on Rohloffs are more likely to occur if the spokes are a little on the short side and the build finishes with some spoke thread still showing below the nipples. I am convinced that some thread, right on the bending point where the spoke exits the nipple would act more significantly as a stress raiser than a smooth spoke shaft....

Some shops that HATE Rohloffs still carry short enough spokes. I know I called Spa to buy some, let on what they were for and got a verbal broadside about heavy, draggy and expensive etc. You can't beat Yorkshire folk for straight talking honesty, no "side" to them  I still love them 

Happy days
Ian

[NZPeterG]

Be carefull about Rohloff sizing as.it maybe close! But for me never right!
With right checking it sounds like 241 would be the size so you need to order 240mm
For strong wheels you need the spokes to come thought the nipple head ( but not passed)


Happy wheel building

Pete......

[phopwood]

Nothing is ever as simple as it should be (as my mum would say).  Yes I now know the calculated spoke length is not as per the Rohloff website and it is in fact 241 for a 32 spoke 2 cross build.   I may order the RIM and measure before believing figures.

So assuming the figure of 241 is correct do I need to order 242 or 240, I assume this will just leave the spoke slightly short or long in the nipple.

I will most likely order the spokes from SJS when I have all this figured out, they seem to stock the shorter spokes.

All the best.
Peter