Sunday, February 11, 2024

The Guitar Ted Wheel Series: Materials - Part 1

Why Aluminum or Carbon Rims May Be Best For You.

What your wheels are made of will help determine the price, but maybe more importantly, how you experience the wheels. Of course, how all that gets put together matters as well. It's kind of like a recipe. You have to get the right ingredients, in the proper amounts, and then prepare them perfectly to get the optimum wheel.

That said, we're going to break it down here to rim materials first. Hubs are usually aluminum. Spokes are usually stainless steel. Sure, there are outliers, but we'll get to that when we talk about the more exotic stuff. 

Rims are pretty much in two camps: Aluminum or Carbon Fiber. Some will tell you that "You gotta have carbon!', while others will tell you "Aluminum rims are just as good but cost less!". Which person is right? Well, let's see about this, shall we?

Keeping in mind that my focus these days is on what works best on crushed rock roads, I will refer to something I discovered when testing some carbon fiber wheels a few years ago now. I was riding a wheelset that was incredibly stable on loose gravel. The bike I had the wheels on I was intimately familiar with, so I knew it wasn't the bike, it was these new wheels I was testing. What was going on here?

These wheels had a profound effect on my understanding of what makes a good wheel.

I'll fast-forward to the good part and spare you all the testing observation. What I found was that these wheels did not oscillate, or 'wobble' in deep, loose crushed rock. They basically were so stiff that the vibrations that would normally induce a wheel to 'wobble' side-to-side weren't having much of an effect on the wheels. 

This really opened up my eyes because I then saw why certain wheels were a chore to ride while others felt better and felt "smoother". This is definitely not what I was looking for, but I found this to be true, and it is why you want stiff rims. Stiff laterally. Not vertically, but unfortunately that probably will be the case anyway. (I'll get to all that later)

So, "Just get carbon fiber rims, right?". Well.....not so fast. Some carbon rims aren't all that stiff laterally, and some aluminum rims are. But yes - In general, getting carbon rims will give a better ride, just not for the reasons you may have thought. Vibration absorption is not a factor. I'm not saying it doesn't happen, but if you are running 35mm-plus wide tires and at a realistic pressure (not MAX). your vibrations are getting soaked up more by tires than by any rim. And there are vibrations at certain frequencies that are going to get passed through to you no matter what. There is no magic bullet. 

But having a wheelset that doesn't oscillate in chunky gravel is a boon to handling and allows the rider to relax, spending less energy on corrective inputs, and then be able to exert more effort into pedaling over a longer period still feeling fresh. 

Other Considerations: As stated, some aluminum rims ride very well, and you can get pretty decent weight wheels for not a lot of cash. Aluminum lasts a long time, is resistant to gravel stones pinging off them, (and they will), and also will do tubeless or tubed very nicely. While spoke count matters for other reasons more heavily, having more spokes is generally better if you want stiffness laterally. However, unless you have your wheels built up, or build your own, 28 spokes is going to be max and there are a ton of 24 spoke count wheels. I'm of the opinion that pre-built, low spoke count wheels aren't always the best thing, especially for riders that want to do some bikepacking, touring, or that are heavier people AND also want to carry stuff on the bike. 

Image courtesy of HED Wheels

Good quality carbon rimmed wheelsets will automatically push you into a price range that isn't cheap, and maybe that's uncomfortable, but I would seriously consider carbon rims for ride quality and especially if you are concerned about rotating weight. That's a place where carbon will also make a big difference without sacrificing strength, in most cases. 

Carbon is pretty tough these days, but do be aware that pinging rocks will ding up the finish and theoretically could damage a rim to a point that you'd be advised to replace the rim. 

I'd stay away from hookless designs in carbon just because they are not high pressure friendly and if you end up having to put a tube in to get you home those hookless designs are not meant for tubed applications, so.... 

Another advantage to carbon rims is that they are resistant to damage from sealants. Aluminum will corrode when exposed to ammonia, which many sealants have in them as one of their ingredients. Any exposed parts of the inner rim well due to tape slippage can be corroded by sealant and allow spoke nipples to be exposed to sealant, which is really bad if you have alloy nipples. This is a common issue with aluminum rims that are used tubeless. 

One other thing that may be of concern if you live in a rockier area is the tendency for aluminum rims to be dented. This can happen when using low pressures and when speed and bigger rocks are in play. Carbon is more resistant to such damage, but it is not impervious to being damaged in this way. 

Of course, any pre-built wheels you consider may have weight limits, so it is wise to check on that before purchasing any wheelset. Be aware that anything you carry on you or on the bike is weight that needs to be considered in that weight limitation as well. Riders needing to have wheels to bear up under their weight and a load, or are just heavier humans, should consult a wheel builder and have a custom set of wheels made just for them. Rims are part of that equation, but I'll get into all that matters with custom wheel builds after I finish up on the materials in my next post. 

Conclusions: Carbon or aluminum? Either can be a great choice. Carbon will cost you more money, all things being equal, but can bring the ultimate performance benefits. Aluminum is a value in that the performance aspect can be very high, but the cost of an aluminum wheelset usually is quite a bit less and for utilitarian purposes, this material is perfectly suited for a rim. Not to say that you cannot race on an aluminum wheelset. You can, and this works well for many riders. 

Personally, I have both types of rims in regular service and I can recommend either as long as the wheel is built well with quality parts and is used appropriately. I have found that carbon is best on gravel due to that "wobble" characteristic described above and that aluminum rims just don't quite have as good a result in that way. Close, but not quite. So that's my personal take on it. 

Next: Materials Part 2: Alternative Spoke Materials For Gravel Riding

1 comment:

MG said...

I tend to agree with most of your sentiments here. I don’t worry too much about hookless sidewalls since I can’t remember the last time I had to put a tube in on the trail, but YMMV. Recently, I pulled the Bontrager Aoleus Pro 3V carbon wheels from my GT and replaced them with my alloy Shimano GRX wheels and was surprised at how good the ride quality was with the GRX wheels. With barely 100g of weight difference, the spin up difference was negligible, but so too was the difference in ride quality. Very impressive… I’d have no problems running those GRX wheels all the time if they were all I had.