I'm getting the parts together to build a new wheel. This will be the 3rd rear that I've done.
The last rear that I built developed a crack spreading from one spoke hole to the two adjacent holes. I think this might have been caused by excessive tension on that side of the wheel (too late to check as I disassembled a while ago.
So, when doing spoke length calcs on wheelpro I noticed the spike tension ratio at the bottom of the results.
Is this just a simple ratio of tension as a guide to what the final tensions should be?
techno wrote: ↑Tue Feb 02, 2021 9:15 pm
Is this just a simple ratio of tension as a guide to what the final should be
I would say so. The way I would interpret that is to ensure one side is 60% of what the tight/drive side would be. I would agree that you probably had the tensions way too high tht you got the cracking at the rim wall etc.
Some manufacturers (I think Stans is one of them) and most carbon rims will come with a guide tension rating for the rim in general. Just ensure that the less tensioned side is 60 percent of what the tight side is... One thing IMO most newer builders suffer is that they can't appreciate how 'not so bloody tight' the spokes don't need to be...
As a general rule of thumb (this works for me), once you have the radial and lateral true just right with even spoke tensions on either side. You'll know your at the end of the build/true if you add a tiny but more tension and the amount of pull of the rim feels amplified. If that makes sense and once you get to this happy place, just back off and be happy
techno wrote: ↑Tue Feb 02, 2021 9:15 pm
Is this just a simple ratio of tension as a guide to what the final should be
I would say so. The way I would interpret that is to ensure one side is 60% of what the tight/drive side would be. I would agree that you probably had the tensions way too high tht you got the cracking at the rim wall etc.
Some manufacturers (I think Stans is one of them) and most carbon rims will come with a guide tension rating for the rim in general. Just ensure that the less tensioned side is 60 percent of what the tight side is... One thing IMO most newer builders suffer is that they can't appreciate how 'not so bloody tight' the spokes don't need to be...
As a general rule of thumb (this works for me), once you have the radial and lateral true just right with even spoke tensions on either side. You'll know your at the end of the build/true if you add a tiny but more tension and the amount of pull of the rim feels amplified. If that makes sense and once you get to this happy place, just back off and be happy
It's worth searching out a spoke tension spreadsheet on the net that plots them into a wheel graph as it gives a really good indication to what needs tightening and loosening and really helps with truing. I just use a cheap Lifeline tensionometer which are £35 from CRC.
htrider wrote: ↑Tue Feb 02, 2021 10:18 pm
It's worth searching out a spoke tension spreadsheet on the net that plots them into a wheel graph as it gives a really good indication to what needs tightening and loosening and really helps with truing. I just use a cheap Lifeline tensionometer which are £35 from CRC.
I've got my bro's park tension meter. Will look for a spreadsheet. Think there are apps too actually......
I have Iwo pairs of wheels myself. 3 of the 4 have been fine. I did this by following the g-sport and Ali Clarkson wheelbuilding guides.
Having noticed the spike tension ratio in the wheelpro spoke calc results I thought "I'll pay for Roger musings book as it's bound to be mentioned in there."
It's not
I think the spoke tension ratio has been added as it's interesting and showing off how clever the math is, but it's of no use when building wheels.
The driveside will be at whatever tension you have decided is right for the rim. The non-driveside will be whatever it is when the wheel is dished correctly. If the calculator is correct this will match the figure given, but if it doesn't then it's not an issue. If you then alter the tension on the non-driveside so match the calculator it will change the dish of the wheel.
ScotRoutes wrote: ↑Wed Feb 03, 2021 10:46 am
I'm sure everyone is remembering to recalibrate their spoke tension gauge regularly.
I had thought about checking mine as out of all the instruments I have it's the easiest to check. All I have to do is make an adapter to hang a spoke off the engine crane and and another to hang a known weight off the bottom of the spoke. If I hang 100kg on the spoke the meter should show a tension of 100kg.
Unfortunately it's on the list of things to do which would be interesting but not urgent so I never get round to it.
I'm sure everyone is remembering to recalibrate their spoke tension gauge regularly
WHy ?
Surley any innaccuracy would be repeated across the wheel so what % out it is the same for all spokes will be that % out but the wheel will still be true it will either be [overall] slightly tighter or loser than the spreadsheet says
or to put it another way if I make every spoke 3 % tighter or looser on a true wheel its still true at the end of the process
techno wrote: ↑Wed Feb 03, 2021 10:30 am
I have Iwo pairs of wheels myself. 3 of the 4 have been fine.
techno wrote: ↑Wed Feb 03, 2021 10:30 am
Waste of £9
Not really, if you follow the book then 4 of the 4 would have been fine
True if I'd bought the book prior to building any wheels. But I didn't.
Also, having read the book there's not much (apart from applying tape flags to the spokes to monitor twist, good idea) that I haven't already been doing. It's possible the cracked rim was caused by a stress fracture from a poorly drilled hole or other manufacturing error.
Like I say. A waste of £9.
techno wrote: ↑Wed Feb 03, 2021 12:12 pm
Like I say. A waste of £9.
Also, if you use the spoke calculator then book sales funds the web hosting, which keeps the calculator add free, so your purchase means I don't have to look at adverts
More of an issue for me is that I have a wheel to build (spare non-dyno for the singlespped) and I usually buy my spokes from Rose bikes who no longer ship to the uk, but well... blue passports and all that
sean_iow wrote: ↑Wed Feb 03, 2021 12:40 pm
More of an issue for me is that I have a wheel to build (spare non-dyno for the singlespped) and I usually buy my spokes from Rose bikes who no longer ship to the uk, but well... blue passports and all that
Try SpokesFromRyan in Bristol, they've been my go-to for spokes for a couple of years. Salim D-lights in particular are pretty cheap from them.
I use https://www.cyclebasket.com/ for spokes. Their ACI Alpina spokes seem pretty good. Not tried SpokesFromRyan.
Another fan of the Roger Musson book as well. Have built easily 20+ pairs of wheels using his method over the last 10+ years and no issues*. Think possibly the best value £10 I have spent on cycling.
*Well apart from one rear wheel where I built it high tension to see if it made a difference to ride quality and it didnt really, as expected though I did have a few spokes break in use and the rim nipple holes cracked.
I also use the Park spoke tension App. https://www.parktool.com/wta as gives good overview of tension during later stage build. I use a Park TM-1 which I havent had calibrated but I assume it gives me a degree of accuracy and for me more importantly ensures consistent tension between spokes which ime is key to a good wheel build.
