Oh wise ones: Spoke lengths

David Nutter said:

For my rim/hub combination (Shimano NX-30 dynamo and Mavic Open Pro), Spocalc.xls seems to think
that spokes of length 284.7 would be best. Obviously spokes of this exact length aren't available.

My question is, should I buy 284 or 285 spokes?

285 - round to the nearest mm. Those few tenths will be the least of your worries. I hate to worry
you but spoke calculators can sometimes be incorrect by more than one whole mm. Best to use more
than one calculator to check (although the DT online one doesn't seem to include your hub).

By the way I'd really appreciate some numbers the wheels listed below to compare to DT's - if it's
not too much trouble for someone to help. I can't get the full spocalc.xls to download and work on
my computer:

Front wheel #1: Campag Chorus 2001 (new style 9/10sp) 32h Mavic Open Pro 700c 3x

Rear wheel #1: Campag Chorus 2001 (new style 9/10sp) *36h* Mavic Open Pro 700c 3x right, 2x left

Front and rear wheels #2: Campag Mirage 8-speed 1999 36h Mavic MA2 700c 3x

Rear wheel #3: Shimano Nexus 7 36h Vuelta Tempest 700c 3x

cheers ~PB

Advice from DT: "Generally it is worth: When thinner spokes are used, the more the calculated spoke
length can be rounded down and vice-versa!!!" www.dtswiss.com/index.asp?fuseaction=spokes.bike -
Spoke Calculator

~PB

David Nutter said:

Hello,

For my rim/hub combination (Shimano NX-30 dynamo and Mavic Open Pro), Spocalc.xls seems to think
that spokes of length 284.7 would be best. Obviously spokes of this exact length aren't available.

My question is, should I buy 284 or 285 spokes? Nothing I've seen in the Bicycle Wheel or online
seems to indicate that either length is better than the other as 1mm difference from the ideal
length each way seems to be entirely acceptable, however I may have misunderstood or missed
something.

Intuition tells me that 285 would be the best length, intuition is not always the best counsel
of course!

Any advice appreciated[1].

Not exactly scientific, but I always [well on the 6 occasions I've built wheels] round down, mainly
because there's less chance of the spokes poking through the nipple and into the rim tape [although
this obviously depends on the style of your rim I guess...mine are basic!], and also if the spoke is
too long there might be a chance that all the threads on the spoke may not grip the threads of the
nipple... although the reverse of this is also true if threads are visible on the spoke after you've
finished building the wheel!! Bet it doesn't really matter 'that' much at the end of the day.

Garry

Pete Biggs said:

David Nutter said:

For my rim/hub combination (Shimano NX-30 dynamo and Mavic Open Pro), Spocalc.xls seems to think
that spokes of length 284.7 would be best. Obviously spokes of this exact length aren't
available.

My question is, should I buy 284 or 285 spokes?

285 - round to the nearest mm. Those few tenths will be the least of your worries. I hate to worry
you but spoke calculators can sometimes be incorrect by more than one whole mm. Best to use more
than one calculator to check (although the DT online one doesn't seem to include your hub).

Argh, nothing is ever simple

By putting the same hub numbers as Spocalc into the DT calculator, I get
283.3. The difference seems to be that DT thinks the Open Pro is 602mm in diameter while Spocalc
thinks it is 605mm. By tweaking the rim diameter number, I get 284.7 again indicating the
same equations are used at least 🙂

Quoted message said:

By the way I'd really appreciate some numbers the wheels listed below to compare to DT's - if it's
not too much trouble for someone to help. I can't get the full spocalc.xls to download and work on
my computer:

I've converted the Hub and Rim datasheets from Spocalc into PDF if that's useful for you.

You can get them here:

dur.ac.ukspocalc hubs.pdfOpen ↗ and
dur.ac.ukspocalc rims.pdfOpen ↗

Perhaps the Spocalc spreadsheet without the rim and hub dbs will work for you? If not I'll do the
calculations for you this evening, if nobody else obliges first.

Regards,

-david

Garry Broad wrote: ...........

Quoted message said:

although the reverse of this is also true if threads are visible on the spoke after you've
finished building the wheel!!

One trick to get round that is to use 16mm nipples instead of 12mm as they have 2mm more thread. I
checked, with new DT nipps, after Jobst Brandt said it wasn't true! :-)

Quoted message said:

Bet it doesn't really matter 'that' much at the end of the day.

It doesn't (you can get away with one or two mm out quite easily) - except when you've chosen the
wrong lengths in the first place, so that final millimetre can make the difference between the
spokes being useable or not.

~PB

David Nutter said:

By putting the same hub numbers as Spocalc into the DT calculator, I get 283.3. The difference
seems to be that DT thinks the Open Pro is 602mm in diameter while Spocalc thinks it is 605mm. By
tweaking the rim diameter number, I get 284.7 again indicating the same equations are used at
least 🙂

DT have some special notes about Mavic rims in the "instructions" (something about Mavic's errors
and offset holes, etc) but I must admit that they're as clear as mud to me.

Quoted message said:

I've converted the Hub and Rim datasheets from Spocalc into PDF if that's useful for you.

You can get them here:

dur.ac.ukspocalc hubs.pdfOpen ↗ and
dur.ac.ukspocalc rims.pdfOpen ↗

Thank you very much! I'll have a go with those tonight or tomorrow.

Quoted message said:

Perhaps the Spocalc spreadsheet without the rim and hub dbs will work for you?

Probably will but I'm not sure. I should be able to use the numbers one way or another.

Quoted message said:

If not I'll do the calculations for you this evening, if nobody else obliges first.

Cheers!

~PB

Pete Biggs <[email hidden]> said:

Your numbers:

Quoted message said:

Front wheel #1: Campag Chorus 2001 (new style 9/10sp) 32h Mavic Open Pro 700c 3x

Spocalc says: 296.5 for a three-cross.

I used the following hub entry:

2.4 39.0 35.4 39.0 35.4 F 100 Campagnolo Chorus, Daytona OS 2002 Mar 01 www.campagnolo.com

Quoted message said:

Rear wheel #1: Campag Chorus 2001 (new style 9/10sp) *36h* Mavic Open Pro 700c 3x right, 2x left

I think you're on your own with this one! Spocalc won't let me specify different crossings for
drive/non-drive spokes.

Quoted message said:

Front and rear wheels #2: Campag Mirage 8-speed 1999 36h Mavic MA2 700c 3x

IN both cases I'm using the appropriate entries titled

"Campagnolo 1999+ Athena, Veloce, Mirage".

Note that Spocalc thinks the rear hub is 9spd.

For the front:

3.0

For the rear:

4.2 on the left.
5.4 on the right.

Quoted message said:

Rear wheel #3: Shimano Nexus 7 36h Vuelta Tempest 700c 3x

Unfortunately spocalc has no dimensions for the Tempest rim.

Hope this is useful.

Regards,

-david

David Nutter wrote: /snip

Quoted message said:

Quoted message said:

Rear wheel #1: Campag Chorus 2001 (new style 9/10sp) *36h* Mavic Open Pro 700c 3x right, 2x left

I think you're on your own with this one! Spocalc won't let me specify different crossings for
drive/non-drive spokes.

Nevermind, I'll use DT's calculator and Spocalc's database numbers.

Quoted message said:

Quoted message said:

Front and rear wheels #2: Campag Mirage 8-speed 1999 36h Mavic MA2 700c 3x

IN both cases I'm using the appropriate entries titled

"Campagnolo 1999+ Athena, Veloce, Mirage".

Note that Spocalc thinks the rear hub is 9spd.

Not the right one then (dishing will be different). Maybe my hub is '98 or Avanti (probably Avanti
anyway but I was assuming Mirage was the same.).

/snip

Quoted message said:

Hope this is useful.

It is. Many thanks!

~PB

David Nutter said:

Quoted message said:

Rear wheel #1: Campag Chorus 2001 (new style 9/10sp) *36h* Mavic Open Pro 700c 3x right, 2x left

I think you're on your own with this one! Spocalc won't let me specify different crossings for
drive/non-drive spokes.

The usual way to get around that is to run the numbers twice as if it was two wheels: one all 2x and
one all 3x then just take the appropriate results from each side. But please don't bother doing that
for me as it's not urgently required.

cheers ~PB

Pete Biggs said:

The usual way to get around that is to run the numbers twice as if it was two wheels: one all 2x
and one all 3x then just take the appropriate results from each side. But please don't bother
doing that for me as it's not urgently required.

Dorr, of course. I plead doing the calculations at 0830 in the morning before the magical life
giving tea was drunk... 🙂

Regards,

-david