Cycling UK Forum

I want to build some fixed wheels on Chrina rims but checking the website:

http://www.ses-sandmann.de/art/ERD%20Di ... Rigida.htm

gives ERD of 603.5 (for the double eyelet version) where as Spocalc says 608

I'm uncomfortable with such a large difference between the two. Has this rim changed at some time and one database is using the old size or something?

Anyway - does anyone know the true ERD of the 700c Chrina?

If anyone has spoke lengths can they give hub details too please so I can work back to the ERD?

Thanks

I can tell you what I measured.
I've made two sets of Chrina wheels.

603.5mm

When you calculate your spoke length, make sure you round up to the mm. If it's a whole mm, round up another mm. better to have the spokes a mm or two too long, than too short.

Just wait until you have them in hand - seriously, I have far too many spare spoke sets from being impatient and ordering before having the hub/rim to measure.

If you're using ambrosio/system-ex/on-one style budget fixed hubs then you are likely to need 292mm (rear hub, 32h, 3x) or 290mm for 36h. Unlike Mick, unless it's very close (<1mm) I tend to round down with spokes - nothing more annoying than having zero tension after going round with nipple driver and then having to do 3+ rounds with the spoke key before the nipples stop turning freely. Just my preference mind.

I recently built up some chrinas and they came in at 604mm by my measurement.

GrahamG wrote:...... Unlike Mick, unless it's very close (<1mm) I tend to round down with spokes - nothing more annoying than having zero tension after going round with nipple driver and then having to do 3+ rounds with the spoke key before the nipples stop turning freely. Just my preference mind.

There's nothing more annoying to me to see threads showing! As much thread as possible should be in the nipple.

If your spoke length comes out as x.5mm, round up to x+1mm. If it were to come out as x.9mm, I'd round up to x+2mm, not up (only) to x+1 and not down to x-1mm. Round up is the best way, never down.

With the Chrina, the spoke holes are very recessed inside the rim, so any spoke poking out through the nipple won't interfere with the rim-tape or tube.

I've never used a nipple driver, I just use my fingers.

Thanks everyone for your responses - it looks like Spocalc is wrong and the other site is correct!

GrahamG - I know I should wait but all the responses agree now and your spoke length specification confirms 603.5/604.

As to rounding it's a difficult call. Last time I built 26" wheels I had to subtract a couple of mm from the Spocalc. My last set of 700c wheels I rounded down and should really have gone up.

Cheers.

I find its quicker to just compare an "unknown" rim with a couple of "known" rims than to use a spoke calculator, and usually more accurate, too, so I dont do ERD's.
I can't remember what I use for fixies, except that for 36H, L/F, rear, you ideally want an odd number of mm. length spoke, which we currently cant get out of the importer. My book is at work, of course. (The front wants a longer spoke, due to wider apart spoke flanges.)
If it helps, I can remember the most common set we build, which is 36H, 3x, 9 speed, Rear is 292/294, front is 294. Usually. Except the pair I built to-day, the front wanted 296. Who knows why??

Rigida Chrina on Campag 32h front, 36h rear.
Bought from Spa.

531colin wrote:I can't remember what I use for fixies, except that for 36H, L/F, rear, you ideally want an odd number of mm. length spoke, which we currently cant get out of the importer. My book is at work, of course. (The front wants a longer spoke, due to wider apart spoke flanges.)

My chrina build was 36h fixed on the usual system ex hubs, 289mm was the odd length, I used 288 both front and rear which was fine although care was needed with the nipple driver. I'll use 290mm next time! Sorry, should have told you this earlier, missed the bit in the original post where you said you were building up a fixed wheelset.

I have recently built a pair of old 105 hubs onto a pair of Chrina rims

I used 608mm as the ERD.

36H hubs, Front 296mm, Rear 294/292mm.

I found the spoke length to be pretty much exact, no threads visible.

These lengths are the same as 531Colin states above.

I have a spare Chrina that I have just compared to a Mavic Open Pro (ERD 605MM) and it's definately "bigger". I actually measured the rim at 607mm.

MickF-Interested to hear how your build goes, IMO, the spokes look a little short. Campag 32H front, I would have gone for 298mm.

http://lenni.info/edd/

Link to spoke calculation website I normally use (It's based on spocalc). It's always been accurate for me.

Anyone any thoughts on rounding up or down?

ph1 wrote:MickF-Interested to hear how your build goes, IMO, the spokes look a little short. Campag 32H front, I would have gone for 298mm.

The above receipt was from two years ago, and the wheels built into a beautiful set. I had done the exact same build a year previous but wrecked them both in a massive pothole! The spoke lengths are fine, no threads showing at all.

The spoke lengths are perfect for my Campag Chorus 2006 hubs. 36h rear and 32h front.You can see from my calculation that I rounded up to 296mm, but all is fine.

531colin wrote:If it helps, I can remember the most common set we build, which is 36H, 3x, 9 speed, Rear is 292/294, front is 294. Usually. Except the pair I built to-day, the front wanted 296. Who knows why??

2 years ago, Spa would probably have sent ACI nipples, which are actually 12.6mm. (or thereabouts) now we use Sapim nipples which are 12mm. . Can make a difference.

I still dont know why Chrina front 36H 3x are usually 294, but occasionally 296, this year.

Still, if it was too easy, it wouldnt be any fun..........

Chrina front 36H 3x are usually 294, but occasionally 296, this year.

I'm building a pair this we/e the fronts worked out at 295 (wheelpro). so I'm using 296

I have been building my Chrina (or is it Chrisna??) rims using the 609 figure.

I have found that I built a few wheels where the spokes were too long by that sort of amount and I put the blame on the DT website as some people accused it of giving too long spoke lengths.
I cant remember if it was happening with Chrina rims only, all rims or just other types of rims. I must look at my wheels and see if I can work out what was the case.

531colin wrote:2 years ago, Spa would probably have sent ACI nipples, which are actually 12.6mm. (or thereabouts) now we use Sapim nipples which are 12mm. . Can make a difference.

Ah!
That does make a difference. An additional 0.6mm may cover the threads, but may not with shorter nipples.