Author Topic: Novice wheelbuilding question - ERD's spokes and rim transplant...  (Read 5485 times)

I am currently eyeing Mike's Ultegra / Rigida Chrina wheels in For Sale.   If I acquire them I'll be wanting to swap over my existing SON from a very worn Open Pro rim into the Chrina.   I have seen the 'tape rims together and transfer spokes' method and wonder if the spokes on my existing SON / OP will fit for a SON/Chrina build.

Can anybody advise please?

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #1 on: April 15, 2012, 06:50:59 pm »
Look up the ERD of the rims.  If they are within 1-2mm, you're OK.  For a more involved answer you need to look at your existing wheels and see whether the spokes are exactly the right length (to the bottom of the slot in the nipple), marginally short or marginally long, as this tells you how far you can err and in what direction.

EDIT: Mavic is 605mm, Rigida is 608mm.  As long as your existing spokes aren't a bit on the short side, it should be OK.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #2 on: April 15, 2012, 07:06:33 pm »
photos tonight I promise, PB!! Just a small matter of a very good pinot noir keeping me from the garage at the minute....

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #3 on: April 15, 2012, 07:28:29 pm »
I am currently eyeing Mike's Ultegra / Rigida Chrina wheels in For Sale.   If I acquire them I'll be wanting to swap over my existing SON from a very worn Open Pro rim into the Chrina.   I have seen the 'tape rims together and transfer spokes' method and wonder if the spokes on my existing SON / OP will fit for a SON/Chrina build.

Can anybody advise please?

Open Pro and Chrina are interchangeable unless you're very unlucky - 2mm difference in effective diameter IIRC.  Don't pull these apart though - you'd need new spokes to fit to the much larger SON hub -  just buy a new Chrina for less than 20 quid from Spa and fit that.  You'll then have a spare front wheel for daytime training rides and spare the wear on the dynohub.

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #4 on: April 15, 2012, 10:06:04 pm »
I am currently eyeing Mike's Ultegra / Rigida Chrina wheels in For Sale.   If I acquire them I'll be wanting to swap over my existing SON from a very worn Open Pro rim into the Chrina.   I have seen the 'tape rims together and transfer spokes' method and wonder if the spokes on my existing SON / OP will fit for a SON/Chrina build.

Can anybody advise please?

One of the frustrations with wheel building is the difficulty of calculating spoke length because their so much wrong and contradicting info on rim ERD, a crucial number when calculating spoke length. Eg. Mavic Open Pro ERD is often stated as 602 mm or 605 mm. The Rigida Chrina as 603.5 mm or 608 mm.
If you are very unlucky this may mean that the spokes may be too long, especially if they are protruding above the nipple slot in the present SON/OP build.
Too long spokes can't be salvaged, but slightly too short spokes aren't a problem: Some thread showing beneath the nipple shank may look wrong but really isn't a problem. If there is too much thread showing, then 14 mm or 16 mm DT Swiss brass nipples can be used to "extend" the spokes 1 or 2 mm.

Personally I don't really trust any wheel data unless I measured myself. That said, I suspect that the spoke length will be practical identical between Mavic the Open Pro and the Rigida Chrina. The best ERD data for the Mavic Open Pro I have seen is from a wheel builder who not only build wheels but also actually measured the Open Pro ERD himself as 603 mm using Wheelsmith rods.
This pdf
http://www.cycleservicenordic.com/product-images/Filer/Teknik/Rigida/Rigida_Rim_Type_and_ETRTO_2012.pdf

states that the Rigida Chrina (double eyelet version) has an ERD of 603.5 mm.

It would make a lot of sense that Rigida would make a box rim that matches the spoke length of a very popular Mavic rim. So, no guarantee, but I suspect that the Chrina rim will fit perfectly on the spokes from the SON/OP wheel.

Some other advice. Spoke wind-up is the wheel builders enemy number one, so; lubricate both threads and nipple wells/eyelets, and when you tighten the nipple, turn the spoke key eg. 1/2 turn forward and then back off a 1/4 turn.
Be systematic; put a piece of tape on a spoke near the valve hole so you know when you have worked through one side of the rim. A Q-tip or a tooth pick or something similar can be helpful to insert the nipple if the eyelets are deep.

Technically you don't need to stress relieve the spokes since you reuse spokes that hopefully was stress relieved when the wheel was build, but it doesn't harm either and may improve spoke the spoke line; so when the slack is taken of spokes but they aren't so tight they can yield, grab two parallel spokes with one hand and squeeze hard. You can't wreck the wheel by squeezing too hard. Use work gloves or a some cloth around your hand when squeezing. Work through all the spokes.

Put the rim tape on before the spokes are too tight, the forces involved are surprisingly large, so a nipple popping off can (at least in theory) achieve a nasty speed. To paraphrase a manual to a laser device; don't look into the nipple well with your remaining eye.

--
Regards

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #5 on: July 09, 2012, 12:28:54 pm »
Cometh the hour...

I have decided not to dismantle a perfectly good wheel but to have it as standby for my first build / transplant.   I'm going to buy a new Chrina rim and do the transplant.

I'm thinking about what tools I need for this:  I have a crappy wheel jig which I think will do - I intend to put the existing wheel in, set the various bits, then pop it out and transplant the rim.   I also have the appropriate spokey.   

What I have little idea about is how to get the tension close on right or whether I should use a dab of oil on each spoke thread before screwing down. 

Thoughts please? 

Rhys W

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Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #6 on: July 09, 2012, 12:41:13 pm »
What I have little idea about is how to get the tension close on right or whether I should use a dab of oil on each spoke thread before screwing down.

I have a few pairs of faultless Open Pro on Record/Chorus wheels built by my LBS, so when I came to a rim transplant I selected the best of those as a reference for the final overall tension. That "best" wheel was a little highly tensioned imho, so I didn't try to get mine all the way there.

For lubrication I used a smear of Finish Line Cross Country with no adverse effects (i.e. nothing came loose).

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #7 on: July 09, 2012, 04:23:41 pm »
Ah, thanks Rhys.

Should I simply lightly smear the threads or should I put some on the nipple seats too?

This is going to be fun, I think...

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #8 on: July 09, 2012, 04:28:57 pm »
Threads only, IMO.

Oil or grease in the nipple seat just attracts dirt.
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Biggsy

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Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #9 on: July 09, 2012, 04:36:03 pm »
Liberally oil or grease the threads and nipple seats.  Spokes coming loose is not something to worry about for a non-radial front wheel and rear drive side if the spoke tension is good.

Compare tension to another known-good wheel, or just keep on tightening until it nearly feels "oh shit, that's too much".  Admittedly this is easier to gauge after experience of really too much, when the wheel goes a funny shape or the rim deforms and cracks around the eyelets.  The former is reversible, the latter is an expensive lesson.  Nipples rounding is not something that will happen with a good spoke key and modern spoke threads.

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Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #10 on: July 09, 2012, 04:38:26 pm »
Oil or grease in the nipple seat just attracts dirt.

It helps you get turn the nipples when they get tight.  It's important, IMO.
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Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #11 on: July 09, 2012, 05:58:14 pm »
...

Personally I don't really trust any wheel data unless I measured myself. That said, I suspect that the spoke length will be practical identical between Mavic the Open Pro and the Rigida Chrina. The best ERD data for the Mavic Open Pro I have seen is from a wheel builder who not only build wheels but also actually measured the Open Pro ERD himself as 603 mm using Wheelsmith rods.
This pdf
http://www.cycleservicenordic.com/product-images/Filer/Teknik/Rigida/Rigida_Rim_Type_and_ETRTO_2012.pdf

states that the Rigida Chrina (double eyelet version) has an ERD of 603.5 mm.

It would make a lot of sense that Rigida would make a box rim that matches the spoke length of a very popular Mavic rim. So, no guarantee, but I suspect that the Chrina rim will fit perfectly on the spokes from the SON/OP wheel.

You know, there have been umpteen threads about Chrina and Open Pro rims that hint at their compatibility, but not once have I seen a direct answer before! V. useful, thanks "interested" (& tewdric).
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Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #12 on: July 09, 2012, 06:51:34 pm »
Oiling the rim/nipple interface is more important than oiling the threads, although I do both (actually, I drop the nipples in an eggcup of 3-in-1).

I would always use new nipples.  They are not expensive compared to spokes.

A four-sided spoke key is important if you want to get the wheel screamingly tight.  Pedro's make a super one.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #13 on: July 10, 2012, 12:16:28 am »
(actually, I drop the nipples in an eggcup of 3-in-1).


I was about to say that.

Re: Novice wheelbuilding question - ERD's spokes and rim transplant...
« Reply #14 on: July 10, 2012, 09:53:57 pm »
You know, there have been umpteen threads about Chrina and Open Pro rims that hint at their compatibility, but not once have I seen a direct answer before! V. useful, thanks "interested" (& tewdric).

I've posted somewhere here about successful1 transplant of Chrina in place of Open Sport (can't recall how OP compare to OS).

1 until I tried to get a tyre on the Chrina, wish I'd chosen another open sport.