Krampus.

6 03 2013

Well, the Krampus seems to have been remarkably popular. A few of the frameset/wheel kits came into the UK recently and initially I thought I might miss out – I probably should have been more organised! However, thanks to some very good folk (tim at Sideways Cycles and David at Bothy Bikes) I am one of the lucky few to have my mitts on one of the bass boat green frames, two Rabbit Hole rims and strips and two 29×3 Knards.

The first step was to measure the ERD of the rim: I assumed that the provided ERD of 615.5 would take into account the +/-7mm offset nipple drilling. I was correct. The ERD is ~617.5 (the accuracy of this measurement puts it between 617-617.5).

So, plug the numbers for my build (XT centre lock hubs f+r and DT comp spokes with 12mm alu nipples) into the calculators and out pops 300mm spokes for the rear wheel (built with the offset to the left side, to make the spoke tension pretty close to symmetrical) and for the front wheel I need 301mm (offset to the right, again to make it near symmetrical tension).

Of course, getting hold of 301mm spokes is not easy. If I err on the longer side with 302mm and the ERD is nearer the lower figure in the range, I might have to do a fair bit of grinding in order to stop the spoke ends piercing the rim strip. More of a concern would be the thread bottoming out in the nipple – there is 1mm to play with once the nipple is ‘full’ of spoke and for alu nipples, you want the nipple full to at least the bottom of the nipple slot, ideally all the way to the top.

So, options are:
1) build the wheel with alu nipples and 300mm spokes and see if the nipple is full enough.
2) err to the other side and use 302mm.
3) I could use 300mm spokes and brass nipples that dont need such accuracy for longevity.

I’ll probably build the rear wheel first and see how accurate my figures are as 300mm is pretty much dead on for that build and decide on the front wheel after.

Screen Shot 2013-03-04 at 21.02.33

Screen Shot 2013-03-04 at 21.04.10

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9 responses

6 03 2013
Roger

SJS have 301mm spokes. I always get spokes from there as they have good stock of odd lengths.

6 03 2013
velopest

Thanks Roger! Useful to know. I tend to use black spokes – no luck there! Will keep an eye. Jon at Just Riding Along does odd sizes sometimes, and Tim at Sideways has a Phil spoke roller/cutter iirc…

6 03 2013
Roger

Oh, shame they stop at 300mm in black. Probably can order them in. Looking forward to seeing the build anyway. Just ordered a Knard 29×3 for my new Jones. On a boring old P35 rim tho’!

7 03 2013
Philip Moore

What spoke calculator do you use?

7 03 2013
drjon

the pics above are taken from freespoke

http://kstoerz.com/freespoke/

it’s pretty good…i tend to do the measurements myself rather than use the database…but i like the pictorial representation and the estimation of tension each side.

14 03 2013
thelazyrando

FWIW – I’ve got two Pugsleys – one built with AL nipples and one built with brass nipples. 4yrs in and the brass bike has seen far worse conditions, but the wheels are 100%. The AL nipples are corroded so bad a bunch of them are mostly dust.

14 03 2013
velopest

yeah…its odd. some folk i know have constant problems with alu nipples, i never have. i have bikes that have been commuted on through salt and rain, for years. i have mountain bikes with wheels that were built years ago and are never polished or wiped down. i build them with oil between rim and nipple and with loctite sealing the thread. However, I do not store my bikes in such a way that they remain wet for long and i wonder if this may be part of the reason? interesting! i dont care about weight that much either…part of my near insistence of using alu nipples is because i feel you should be able to in almost any circumstance.

14 03 2013
thelazyrando

I think it may also have something to do with the anodization on some AL nipples being more protective than others. I’m not sure about that, but for sake of less hassles I’m using brass nipples these days.

The key thing is you aren’t having that problem so it doesn’t matter.

Enjoy the new Krampus!

15 03 2013
drj0n

you might well be right there….the black anodization on DT nipples seems pretty robust and is inside the thread too iirc…thanks!

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