How do you evaluate a wheelset?

Question

I'd like to upgrade my wheels but beyond the price, I'm not sure how to compare different options or even to tell if a given wheel is an upgrade or a downgrade from my current wheelset. I'm looking for an improvement in performance in aerodynamics, weight and reduced rolling resistance.

There's a huge array of wheels available. Ranging in price from $100 to many thousands. What do you look for in a quality set of wheels? I assume total weight is one of the most important factors, but I also imagine that low resistance in the hubs would be at least as important.

I have many questions:

• What's the most important part of the wheel? Hub or rim? Or both?
• How do you evaluate or compare different hubs?
• How do you evaluate or compare different rims/spoke combinations?
• Are there other factors I've missed?

EDIT: What I want to establish is that if I'm comparing two wheels in a showroom or looking at their technical specs, how do I tell which is better and whether they're good value for money or not.

Answer 1

I'm looking for an improvement in performance in aerodynamics, weight and reduced rolling resistance.

If this is what you want then you can pay for light hubs with high quality bearings that give you low rolling resistance. The rest of rolling resistance is due to your choice of tire and tire pressure. Be aware that the claims that weight on a wheel is more important than weight on the frame is based on an evaluation of weight at the perimeter of the wheel, not at the center so the weight savings of the hub may not be as critical as weight savings elsewhere in the wheel.

Aerodynamics-wise, low spoke count wheels are better.

Fewer spokes means decreased stiffness and spoke life, while additional spoke counts can lead to higher power requirements, or overly stiff wheels which are punishing on rough roads.

Low spoke count wheels are not necessarily lighter though -- I believe most low spoke count wheels use heavier gauge spokes and nipples to compensate for the higher tension -- the bigger nipple spreads the force over a larger area of the rim to prevent light rims from buckling.

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(Leaving the rest here so this answer is useful to other readers)

It depends what you're going to use the wheel for, but I'm answering assuming you want a reasonably light durable wheel that you can fix yourself if you have a breakdown, and that you don't have a van pacing you with spare wheels.

What's the most important part of the wheel? Hub or rim? Or both?

Spokes. A low spoke count wheel on a high quality rim and hubs is still a crap wheel. Low spoke count wheels require each spoke to be that much more highly tensioned. Low spoke count wheels are made by machines that push on the whole perimeter of the wheel as they tension the spokes. No human can do that on the side of the road, so this means that if one spoke breaks, you have no real chance to retrue the wheel by tightening or loosening other spokes to compensate.

High spoke count wheels (36 spokes for example) may have slightly higher drag, but there's so many spokes, that you can actually use that little spoke wrench that comes with your multi-tool to do road-side repairs.

How do you evaluate or compare different hubs?

Look at reviews. You basically have to relace the wheel every time you go through a hub, so I prefer long-life over lighter-weight, buy YMMV.

Phil wood is my personal favorite, but again, probably not ideal for racing.

How do you evaluate or compare different rims/spoke combinations?

Jobst Brandt's book "The Bicycle Wheel" explains spoke lacing patterns.

Major rim choices include

• offset vs centered spoke holes. You can get less dish (see below) sometimes by using offset spoke holes
• depth of rims
• thickness of material. Thinner is lighter, but if you're going to do a lot of wet weather riding and you have rim-brakes, then grit gets into the brake pad which will wear down thinner rims more quickly than thicker rims.
• material. Some people actually sell Carbon Fiber rims but if you're using rim brakes then you want the rim to be made of a heat-conductive material so it sheds heat well. Carbon fiber does not.
• type of tire. Clinchers vs tubular. If you don't know what this means, then you're using clincher tires which have a metal (or kevlar) bead, a stiff wire that runs around the inner perimeter of the tire and presses it against the rim.

Are there other factors I've missed?

Dish. If you have a derailleur on one side of the wheel, you can't quite center the wheel over the hub so you have to use longer spokes on one side. This means you can't get both sets of spokes up to the same tension you could if you didn't dish the wheel resulting in a slightly weaker wheel.

Answer 2

@Mike's answer is very helpful, but I'd add that there are lots of good wheel sets (prebuilt) out there and a lot of them are great for different purposes. You should factor into your decision the type of riding you do and how a new wheel set my aid you.

If you do a lot of climbing, I'd say look for weight savings. Deep profile rims won't do you much good. Low profile alloy rims will certainly be a better option

If you have mostly flatland and you ride fast, you'll maybe want something more deep profile to aid with aero advantage. If there is a lot of crosswind this can be a factor as well. Deep profile rims and crosswinds can be tricky with handling.

Do you race? tour? ride for fun?

alloy vs. carbon is also a decision. Carbon is certainly fancier and will impress your friends more, but there are plenty of great alloy wheel sets.

You can always go the custom built route and this can get you a great wheel set for a lot less than the popular brand names with comparable or better quality. It's important that you find a builder that you trust and discuss your style of riding with them so they can steer you in the right direction. They will factor in style, rider weight, budget, etc into their recommendations...or at least a good builder will.

Answer 3

What's the most important part of the wheel? Hub or rim? Or both?

The most important part is clearly the skill of the wheelbuilder. No wheel with good hub and good rim but poor wheelbuilding is going to be durable.

To evaluate the rim, consider these:

1. Are the diameter and width fine? Consider what tires you're planning to fit.

2. What material? Good rims are aluminum.

3. Cross section? Best rims are double walled.

4. Spoke hole count, 36 = good, anything less = bad.

5. What finish? Best rims are polished aluminum, preventing initiation of cracks and allowing you to easily see cracks on inspection. However, these days people don't buy rims if they are not black, so manufacturers have come up with ways to make black rims. One of the ways is anodizing. Don't buy these. Another of the ways is powder coating. You may buy these but prefer polished aluminum if such rims are available.

6. Are there eyelets to allow nipples to turn freely?

7. Are there sockets ("double eyeletes") to distribute spoke tension to both walls of a double walled rim?

8. Can you use the rim with rim brakes?

How do you evaluate or compare different hubs?

1. Does the hub have the features you require? They could be:

• Support for disc brake rotors should you need them
• Front dynamo should you use one
• Compatibility with the desired cassette type on the rear

2. Spoke hole count. 36 is good, anything less should not be bought in the first place.

3. Weight. Less is usually better, but if you remove too much weight, there is no long-term durability left.

4. Material. Prefer aluminum for the hub body.

5. Finish. Prefer polished silver aluminum. With polished aluminum, cracks are easier to see and less likely to appear when compared to e.g. anodized aluminum.

6. Bearings. Some hub manufacturers are selling cartridge bearing hubs at a great cost, because they don't have the manufacturing capacity to build cup and cone bearings. This is not for the user's benefit; it's for the manufacturer's benefit. Don't buy these cartridge bearing hubs. Buy only cup and cone bearing hubs that are adjustable and serviceable. At least Shimano has the manufacturing capacity for cup and cone bearings.

7. Freewheel for rear hub. Prefer ones from name brand like Shimano.

How do you evaluate or compare different rims/spoke combinations?

The spokes should pull from the hub flange tangentially, not radially. Don't buy any radial front wheels if you have rim brakes (radial disc front wheels and radial rear wheel don't work so they are not sold anyway). Radial wheels are inherently fragile because if the spokes are tight, they are pulling radially not tangentially from the hub flange at great forces, causing hub flange failure.

There should be 36 spokes. Some manufacturers sell low spoke count wheels, claiming it's an "improvement". It may be an improvement for the manufacturer (less machine time for wheelbuilding machine), but it ain't an improvement for the user. Lower spoke counts are more fragile and less rideable with broken spoke.

The spokes should be triple butted. Cheap spokes are not butted. They make a wheel fail easily, because they are not flexible and thus don't distribute the load over an area of many spokes. Better spokes are double butted with thinned middle section and thicker head and threads. However, the threads being rolled and not cut have a larger cross section than the head. So, the hub flange must have holes large enough to accommodate the threads, thus having a too large hole for double butted spokes. Best spokes (like DT Swiss Alpine) are triple butted to have a head that barely fits to the hub flange.

The nipples should be brass and the nipple threads and nipple heads should be lubricated with machine oil.

If you have no wheelbuilding skills, prefer wheels that are hand built by a professional wheelbuilder. Machine built wheels often have low spoke tension. However, there is no reason to avoid machine built wheels if you have wheelbuilding skills -- you can tighten the spokes left loose by the wheelbuilding machine yourself.