Trice front wheels - spoke tension

[hercule]

I've just had to replace a spoke on my 2006 Trice QNT - an inner side spoke broke at the bend. I'm not sure how long ago it happened, just happened to notice it when I was adjusting the brakes (the two might be related??)

Anyway, I can't help but notice the spokes on both sides seem to be much less "tight" than they were previously. I seem to remember them being as tight as a drum before, now I can squeeze two crossing spokes and get them to move a couple of millimetres or so. But before I go and tighten all the spokes a quarter turn, I thought I'd check if this seemed abnormally loose...

The wheels seem to be running reasonably true - I've got small problem with one of the drum brakes seeming to be a bit off 100% circular, but that has been an issue for a few years and I am able to live with it. I've tightened the new spoke up to the same tension as the old ones and am cautious about messing up the truing by mistake. I'm happy building bike wheels, but trike wheels are a bit more difficult to fit in the truing stand!

[squeaker]

Just been out to the garage... 2mm movement with a strong squeeze on all 6 trice wheels seems typical. Pinging the spokes gave between 850 and 950Hz fundamental frequency according to my phone - YMMV!
I've only tweaked the wheels on my Sprint 26. All were slack relative to my wife's 2006 T.
HTH

[hercule]

Thanks - I'll get out my tuner and strum some spokes tonight and see what I get!


I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

[squeaker]

Thanks - I'll get out my tuner and strum some spokes tonight and see what I get!

Just checked mine again with a better analyser. Running my fingernail around the outer run of the spokes I get a fundamental on the T's front wheels of about 600Hz, whereas the Sprint is around 800Hz. (Thinking back, it was the nearside wheel that was slack on the Sprint, so I tweaked it up to match the offside.) Here's an on-line tone generator, if that helps (but the spokes do generate some harmonics too).
Finally, before you go too far, it might be worth search BROL for some comments about correcting grabbing SA hubs using rigs, dial gauges etc., as I recall this came up a while back.
HTH

[hercule]

Oh dear. I can play about half an octave on the wheel with the broken spoke. The tension on the other side seems a lot more consistent. I think I've got a bit of work to do...

[D.TEK HPVS]

Your welcome to give me a call about the SA drum issue or concerns .
I have an ICE factory dial gauge designed for checking mono mount drum brake wheels (Rarely used) .
Finally sourced a brake shoe "bedding in" gadget tool for increased performance from day one without the normal running in period !

[hercule]

New spoke installed, everything tightened up a quarter turn, and the wheel re-trued - it didn't need much.

Interestingly the brake issue has all but disappeared. Had I not installed locking Sturmey Archer levers last year I don't think I would have noticed it. Now I can get the lever lock to work properly without the shoes rubbing when the lever is released.

It's remarkable how the spokes can distort what otherwise seems a pretty solid hub shell. Mind you, I haven't been out to give it a rigorous road test yet, so I will have to wait and see if this has fixed the issue...

[squeaker]

Cool

[hercule]

Late update to this. Another spoke broke shorty after I'd "fixed" the wheel, and though I had enough spares just to replace that one, I thought there might be more about to go and so stripped the wheel down and rebuilt it with new spokes. So far so good, though there still is a residual degree of irregularity in the brake - not enough to affect function, but I can't adjust my SA locking brake lever to do its parking brake function.

[Brucey]

trikes that are well-used do tend to give their front wheels a very hard time.

I have seen quite a few hard-used trikes (with similar sized wheels) where the wheels themselves only last about as long as a set of M+ tyres. The damage can be remarkable; broken spokes, loose spokes all round, spokes nearly worn through at the crossings, worn hub drillings, cracked hub flanges, worn nipple seatings in the rims.....

If you were breaking spokes and they were going slack as described, the chances are good that the wheels were not properly stress-relieved when they were built. Had the wheel been stress-relieved after two spokes had broken, you might have broken another couple of spokes but otherwise the wheels might have worked OK.

SA drums will pull out of shape if the spoke tension is not sufficiently uniform; if facing a choice between a pulling out a slight hop in the rim and keeping the spoke tension uniform, it is often best to go with the latter.

Do note that in wheels with relatively short spokes like these;

a) the difference between full slack and full tight can be about 1/2 to 1 turn on each nipple

b) adequate stress relief may cause the spoke nipples to require two full turns more in total

c) adequate stress relief may only be accomplished in two stages, depending on how bad the fit of the spokes is in the hub.

If you regularly subject the machine to the highest cornering forces is it possible that the spokes can slacken in use such that the nipples may back out in service. If this is a concern, it isn't a bad idea to use some threadlock on the nipples. You can add a fluid grade threadlock after the wheel is built. Don't worry about nipple seizure per se; you will always be able to move the nipple using a well-fitting spoke key.

cheers

[[XAP]Bob]

Also on a stub axle, hub braked wheel running laterally true isn't all that important.

I have, in extremis, ridden with a well buckled wheel for quite a while (until a replacement arrived) the quarter to half an inch of play was easily visible under my right hand, but far harder to feel.

[deryck]

If you have trouble hearing/measuring the spoke tone/frequency, then you could consider a spoke tensionometer tool which will allow you to measure the Kgf of each spoke and ensure even tension (assuming the tool is consistent)

[deliquium]

If you have trouble hearing/measuring the spoke tone/frequency, then you could consider a spoke tensionometer tool which will allow you to measure the Kgf of each spoke and ensure even tension (assuming the tool is consistent)

Possible problem there deryck - will one fit onto short spokes that cross on a 20"/406 wheel

Obviously radial spoking would be a very bad thing on a front wheel recumbent tadpole trike