Wheels and spokes

[Mulger bill]

Damn! Off the train tonight with 40 minutes to kill before work so I thought I'd rack up a few kms before arriving sweaty and smiling (it's a beautiful evening in Melb.) Not 200 m into it, heading over Collins St overpass to Docklands and PING, clatter, clatter from the front wheel Think I hooked a tram track Tim's gonna be flat out building up bikes for Chrissy too, bugger. I'll have to grab a spoke and do it meself, this is one of the areas I'm still not very comfortable fixing.

Seeing there's no room in the shed for wheels and spokes in the shed til now, let's go. The wheels are Shimano 500s with a bit over 2000 kms on them and this is no 2. I'm not gonna blame the wheelset unless you think I should, I'm 81kgs ATM, should I look at something better?, there's a pair of new Ultegra hubs on ebay due to finish soon...

Shaun

[europa]

Have a go at it yourself Shaun. Wheels aren't hard, particularly when there are only one or two spokes involved. The worst that can happen is that you have to wait for him to have the time to sort out your mess ... but you were going to have to wait that long anyway.

I'd suggest you bring it around to my place ... but seeing you're there and I'm here, that's maybe a bit silly.

Richard

[europa]

The other thought is that if you were to drop the wheel into your lbs, and say 'look, just get it done when you can', you may find it fixed rather quickly. I've found that jobs left to be squeezed into the gaps can get a sort of weird priority and be fixed sooner than you think.

Imagine yourself a bike shop mechanic. You've spent the last week bolting together kid's bikes and hybrids. Wouldn't you like a fifteen minute break to fiddle with a real wheel?

Richard

[Mulger bill]

Tell yer what, I go on leave on the 6th, maybe I'll jump the Overdue and get the resident wheel god to sort it out for me

Shaun

[Mulger bill]

Imagine yourself a bike shop mechanic. You've spent the last week bolting together kid's bikes and hybrids. Wouldn't you like a fifteen minute break to fiddle with a real wheel?

Richard

That's not a bad idea at all It is about the time of year I drop a dozen cold ones in for the lads

Shaun

[Kid_Carbine]

I'm not gonna blame the wheelset unless you think I should, I'm 81kgs ATM, should I look at something better?, there's a pair of new Ultegra hubs on ebay due to finish soon...
Shaun

I've said it before & I'm saying it again, a tight wheel is a strong wheel & a strong wire spoke bike wheel will happily support many times your weight.

Grab pairs of spokes on opposite sides of the wheel & give them a gentle squeeze. If they feel soft & squeezable, then the wheel is well overdue for a tension & truing job. They should have very little give in them & feel nice & tight.
You don't need to be Hurcules, just a firm hand squeeze. Try it at several places around the wheel.
Drive side spokes should be noticeably tighter, but fronts should be even both sides.

It's my guess that the spokes broke at the bend & if this is true, then some more breakages are just waiting to happen as I believe that more of them have already fatigued there. Inspect the broken spoke carefully, under a magnifying glass if necessary, to see what type of fracture it is.

[Mulger bill]

Thanks for the tip Kid, it was the elbow, as I said, I'm pretty sure it was a lateral load that did it. What should I be looking for in that magnifying glass?

Shaun

[Kid_Carbine]

Thanks for the tip Kid, it was the elbow, as I said, I'm pretty sure it was a lateral load that did it. What should I be looking for in that magnifying glass?

Shaun

The type of fracture is what you're looking for.
A fatigue fracture propogates slowly & leaves a fairly smooth surface untill the remaining material is no longer enough to hold it together & it tears, leaving a much smaller patch with a completely different surface texture.

If this is the case, then it's not unusual for other spokes to break during the tensioning job.
Stainless steel is one of the worst materials to make spokes from as it has a low fatigue resistance, but it will still give good service as long as they are tight & are unable to flex at the bend every time the wheel goes round. A tight wheel distributes the load over the whole rim, but a 'soft' wheel sort of 'hangs' from the upper spokes meaning that the cyclic loading is much more pronounced on a smaller number of spokes. [the upper ones]

[Kalgrm]

Drive side spokes should be noticeably tighter, but fronts should be even both sides.

Just to be pedantic for those reading this later: if you're using disc brakes, the difference between tension on the drive and non-drive sides of the rear will not be as great because there is less "dishing" applied on these hubs.

Front wheels with disc hubs will have more spoke tension on the rotor side of the wheel than the drive side, because these wheels are dished to allow for the rotor.

Otherwise, KC is on the money.

Cheers,
Graeme

[Kid_Carbine]

Drive side spokes should be noticeably tighter, but fronts should be even both sides.

Just to be pedantic for those reading this later: if you're using disc brakes, the difference between tension on the drive and non-drive sides of the rear will not be as great because there is less "dishing" applied on these hubs.

Front wheels with disc hubs will have more spoke tension on the rotor side of the wheel than the drive side, because these wheels are dished to allow for the rotor.

Otherwise, KC is on the money.

Cheers,
Graeme

Thanks for the additional info, it's all to do with mindset. My world revolves around bikes with 27" wheels & either single speed or 5 speed clusters, so what I wrote will apply there, but I keep forgeting that time has moved on & things change.
I don't actually own any of these gall-durned new fangled substitutes for a real bike, [opinions may vary] so I forget to make allowances for them.

Thanks again for the additional info. I'll just go back to the dark ages now.