Just built a wheel, and (as I suspected) it turns out that the spoke calculator was a bit over-generous with spoke length. All of the drive-side spokes (it's slightly dished) are protruding almost 3mm out of the nipple (or 1.5mm into the wheel well).
So what next? Obvious solutions are to either rebuild the wheel with the correct length spokes, or to grind down (or dremel) the protruding ends. But I was wondering if there might be a magic bullet out there to save wheel builders like me that are both incompetent and lazy - some sort of cover for the spoke end that would stop it from being a puncture hazard. Something like a veloplug, but dome shaped and designed to fit over the end of the spoke.
Any ideas? I suspect this product doesn't exist, because I can't see it on the SJS web site
Hi been there... many moons ago, its ok in a double skinned rim, on simple single skin rim used 4'' angle grinder with thinner[ for metal ] blade very carefully and checked before rim tape fitting that no sharp edges could affect the rimtape.. bit of a job for any dremel imo too much side thrust for bearing and blade survival.. will
On a single-wall rim you're unlikely to use high pressure tyres (most cheap rims won't allow that anyway) so you can use some thick rim tape and be ok. I've seen many wheels been built -surely not by me - with spokes protruding over the nipple and some Velox rim tape will take care of it. Just make sure you replace it every so often.
Regarding the spokes, I don't like to grind them off, this will leave a burr that you can't really dress, so when you are to undo the nipples it's likely to be a hard job and will ruin the nipples anyway.
It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are...
if the spokes protrude beyond where the rim tape sits then it is going to cause punctures sooner or later, almost regardless of what you do.
You may be able to make it work for a while by fitting corks over the spoke ends before the rim tape is fitted. 'Rim corks' used to be sold for fitting to sprint rims but if you cannot source those you can make something using a 10mm wad punch and a sheet of suitable material (eg cork tile or some high density foam of some kind)
To trim spokes you can use
- a Var spoke trimming tool (single walled rims only) or - you can grind the spokes down (single walled rims only) in situ. [BTW this is how millions of wheels for raleighs etc were made]
In shallow double-walled rims it is more problematic. A simple way of dealing with it is to unscrew each spoke, trim 3mm off it and then retension. [Depending on how you trim the spoke you may or may not need to carefully dress the end of each spoke with a file to avoid chewing up the nipple threads worse than ever.]
Alternatively if you can find a suitable tool (i.e. one with a ~2.1mm dia hole in it, e.g. a security fastener driving bit might do) you can slip it over the protruding end of the spoke and waggle (fatigue) it off in situ.
If you do replace the spokes then it isn't a bad idea to replace the nipples too; several nipple threads will be lost now; they will probably be strong enough as they are but for the cost of them it is best to change them for new.
FWIW if there is a 3mm error in spoke length then there must have been a similar error in one or more of the measurements used to calculate the spoke lengths.
In the spirit of being lazy, I've decided to take the risk of adding a layer of duck tape over each of the intruding spokes, then velox tape over the top.
If/when this proves to be a puncture magnet, I'll go at them with the Dremel. It's nice to have some bike fettling to look forward to!
Brucey wrote:FWIW if there is a 3mm error in spoke length then there must have been a similar error in one or more of the measurements used to calculate the spoke lengths.
Either that, or the calculator was rubbish!
But I think it was probably the former. It's an Alfine 11 hub, and I used on-line measurements (I know, I know). From memory, the calculator reckoned that the difference in spoke lengths for dishing was < 2mm, and so I could use the same spokes all round. In fact (on a 20" wheel) there's a 4mm difference between the DS and NDS spokes.
Hi Spoke calculator? Dremel? Angle grinder? In the 70s you'd clamp the wheel between your knees and get stuck in with a square section file. And there were often more spokes per wheel then too Regards tim-b
Was this a Mavic rim by any chance. There's confusion about ERD versus SSD (Spoke Supporting Diameter) with Mavics. Advice seems to be ERD = SSD+3mm but I usually end up slightly long spokes with Mavic builds so this time I've rounded down on the spoke lengths. I'm about to build an SA CS-R3K into a 26" XC-717 disc rim. Ordered Sapim spokes from Spa last night and had to choose betweeen 2mm increments for DS spokes.
Brucey wrote:FWIW if there is a 3mm error in spoke length then there must have been a similar error in one or more of the measurements used to calculate the spoke lengths.
Either that, or the calculator was rubbish!
But I think it was probably the former. It's an Alfine 11 hub, and I used on-line measurements (I know, I know). From memory, the calculator reckoned that the difference in spoke lengths for dishing was < 2mm, and so I could use the same spokes all round. In fact (on a 20" wheel) there's a 4mm difference between the DS and NDS spokes.
I reviewed many of the available spoke calculators recently and I did find some discrepancies but none that were large enough to explain your result. Which one did you use?
BTW as the rim gets smaller, the difference in left and right spoke lengths in dished rear wheels (using the same hub) gets larger and larger.
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