Hello, I need your infinite wisdom. I was looking at a pair of carbon wheels and the description reads,

"Used but in excellent, low milage condition. Rim strips appear to be in great shape. Just a little off true to between 1/32 and 1/16 of an inch. No scratches, scuffs or nicks in the carbon. Very minor cassette bite on the freehub but nothing that would affect the functionality (see pics). Hubs are in great shape. SEE PICS"

My question is regarding the "true between 1/32 and 1/16" description. What exactly does that mean and does it affect the performance of the wheel?

Thanks guys.

When truing a wheel the theoretical state of perfection is when there is precisely zero side-to-side wobble, in other words the caliper on a truing stand would just touch one side of the rim for an entire rotation, while the caliper on the other side would just touch the other side of the rim for an entire rotation. In the real world everything comes down to tolerances, a level below which you regard the wheel as being acceptably close to perfect to stop fiddling with it. How close to perfection is acceptable depends on how much time you're willing to spend on it and/or how much money you're willing to pay someone else to spend their time on it.

1/16 of an inch is 0.0625" (~1.6mm); 1.32 is 0.03125" (~0.8mm). I'd assume what the seller is describing is a wheel where if you adjusted the caliper such that it just brushed the wheel at one extreme, at the other extreme it would be up to 1.6mm away from the wheel.

I've ridden wheels that have been out of true by far more than that when I've had broken spokes (I broke a spoke 3 miles into an 82-mile ride, and for the remaining 79 miles had a wobble in the wheel that was easily 1/8" if not closer to 1/4"). It's not an ideal situation - if the wheel wobbles too much it rubs the brakes and that really makes getting anywhere hard, and a wheel badly out of true will put more stress on the spokes than a properly trued wheel. When I built my first wheel I was aiming for an accuracy that I'd estimate as being within 1mm or less, and was trying to gauge 0.5mm as best I could by eye (that's roughly 1/64") by trying to judge when the gap between the caliper and the caliper reflected in the rim was about 1mm. If the wheels seem good and the price is good I'd have thought you could pop them in a truing stand and get rid of that slight out-of-trueness.

Do you mean you don't know what true means? Seem odd you would be buying carbon wheels if that's the case. The answer is that it means that as the wheel turns around it wavers back and forth between 1/32 and 1/16 inch. I would assume that is on each side but there's no way to tell. There's also no way to tell if the wheel is that far out of true and also has uneven spoke tension, so there's no way to tell how stable the wheel would be. As noted above it's fairly easy to true a wheel in general, but I would ask why the seller has not done so, and if you don't know what truing is you have some learning to do.

As for performance, that is far more dependent on you than on the wheel.

I agree that someone who doesn't even know what "true" means and most likely has no idea how to measure or correct it is not a good candidate for carbon wheels.

Thanks for the help. And, yes I understand I have a lot of learning to do. That is why I am here.

Why do you say that? I have read that they take a lot of maintenance, which I've been doing my best to read more about.

They may or may not take a lot of maintenance but my point is, as a beginner, I believe you should start with something less difficult, less specialized and cheaper to learn on.

If you've know that and you know nothing about maintenance it makes no sense to buy them. If you want them because they'll make you go faster, forget it. You will not save the amount of energy in a year of riding that you lose by dealing with those wheels instead of RIDING. If you want them because of the bling value then go right ahead - no need to worry about a little out-of-true, because the people who you will impress won't know any better.

I've been riding road bikes for close to 10 years but I've never cared enough to learn the mechanics. I've always relied on my bike shop to do everything for me. I'll fix a flat on my own but that's about it. I've recently developed an interest and moreso a curiosity in learning about road biking. I've completed a few triathlons, but now I've come to a point where I want to do everything I can to improve my time. I understand i have a long way to go. Often, I'm intimidated by snide remarks at the bike shop and on the internet which discourage me but I do my best to ignore them. We all have to start learning somewhere and luckily for me, humans have a pretty decent ability to learn new things.

If you're new to bike stuff you're probably better off buying something cheaper. If you spend a lot of money on top-end gear only to find you don't know how to look after it properly you either create a huge headache for yourself if your expensive new toy breaks and you don't know what to do with it, or a huge expense if your expensive new toy breaks and you have to spend a lot of money on having it repaired or replaced.

Start with something you can learn about easily, the kind of thing where if you break it you can just go and buy another one. If you wanted to start out with motor racing you'd be better off finding yourself something like a 2012 Ford Focus RS that's in good working order, than a 1994 Ferrari Testarossa that's got some rust and an occasional misfire. The Ferrari may go faster but it's going to cost you a lot more money unless you really know what you're doing with it, in which case it might still cost you a lot more money.

Truing a wheel isn't difficult unless there's something wrong with one or more components of it (which is always possible when buying used from an unknown seller). That doesn't mean it's necessarily quick - you need to make sure it's laterally true (i.e. you minimise side-to-side wobble), radially true (i.e. it's round rather than slightly egg-shaped), and correctly dished (i.e. the rim aligns with the centre of the hub rather than being off to one side or the other). Adjusting anything changes everything else, so if you adjust a spoke to correct a lateral wobble you'll change the roundness of the wheel slightly, and if you adjust a spoke to correct the roundness you'll change the lateral trueness.

I've worked on a couple of trashed wheels for practise (stripping down a wheel into rim/spokes/hub and then relacing and retensioning) a few times and built one wheel from virgin parts having had the practise with the trashed wheels. Building my first wheel took me four hours; the first time I assembled the parts from one of the trashed wheels it took me the best part of three hours just to get all the spokes in place and correctly laced, then several more hours fiddling with spoke tensions to get it radially and laterally true, at which point I found the dish was about 1/10" off and I had to readjust everything again.

I certainly didn't intend my remarks to be snide or to discourage you from learning. I also agree that "we all have to start learning somewhere" but I think starting at the top is not the best learning approach.

You never posted the make or model of the wheels you are considering and carbon wheel can be tricky to work on. Many have a low spoke count which makes truing them difficult. Some are molded in one piece and can't be trued at all. All-carbon rims can have poor braking performance and require very specific brake pads to work at all well. More info might help.

OK, one thing to learn is that it's best to give background information up front. All we knew is some guy wants to buy carbon wheels but does not even know what truing is. The logical assumption was that you wanted them because - you wanted them. I had meant to mention the point made above as well - we need more info on the wheels to make any kind of assessment.

Don't know if you were referring to me but my remarks, although said in a humorous way were not snide (indirectly derogatory) but rather direct and accurate, and as you have already improved your speed by training and aren't getting the wheels to impress others they did not apply to you.

Great information, thanks. I never planned on working on the wheel set. I was just having trouble with the description. I have plenty of cheap wheels sitting around if I ever feel adventurous enough to true a set.

BTW, it's a set of clincher Reynolds Attack. I own a Cervélo S2. Before riding, I'll definitely have it checked by my shop.

Perhaps before buying, it might be a good idea to have the shop check them.

As with so many other things a lot of it comes down to how confident you are with fiddling with stuff and how much more time and/or money you're willing to throw at something you buy used.

I recently bought a clock for restoration with a particularly small and fiddly escapement movement. I bought it to learn about the particular type of movement, knowing there's a significant chance that when I take it apart to get it working again something is going to fly across the room and the thing will never work again. I restrict my purchase prices to take that sort of thing into account - if some tiny component pings across the room and I can't find it the rost of the clock is a collection of spare parts, unless I can source replacement parts (which is hard, if I don't know just what it was that pinged). Hence I might pay £10-20 for a clock that needs attention but if a clock is listed at £100-200 I'll leave it, simply because I don't have the expertise to be willing to risk that extra money on an unknown.

Likewise with bike parts if I bought a wheelset for £50 knowing they needed attention I could spend it figuring I'd either fix them and either use them or flip them, or the worst case is they go in the trash and I salvage the hubs and maybe some spokes and rims. If that wheelset cost £500 I'd give it a miss, for me it's not worth the risk. Someone who is familiar with stripping and servicing hubs might be more willing to take the chance because they would be less likely to end up taking the whole lot to a bike shop and paying professional rates to get it fixed.