A carbon handlebar should, at least, in theory, be more compliant because carbon allows for much more flex than aluminum. Subjectively you can feel it but I wanted to find out what my vibration measurements will show so I tested 2 aluminum and 2 carbon handlebars. The results may surprise you!
Cabon can be very stiff and offers a lot of compliance at the same time. There are many great examples of carbon bikes that combine stiffness and comfort but this time I am not interested in carbon frames but carbon handlebars. This is a tricky thing because the handlebar is a crucial part of the bike in terms of not only bike steerability but also safety. You don’t want to have a carbon handlebar with so much flex that the handling will be ruined but also you don’t want a handlebar that can crack easily. Yes, carbon can crack and in general, does not like too much force applied in a very small area (yet handlebar is exposed to those situations because you clamp the handlebar to the stem and you clamp leavers to the thin carbon tubes). This creates anxiety, at least in my head, but carbon handlebars are nothing new in the bike world so it should be safe to use them. You just have to be very careful when installing the handlebar and do not exceed the torque limits. Otherwise, you can really damage the tubes and the handlebar will be not safe to use anymore. With an aluminum handlebar, you don’t need to worry about all of that. But also, you feel that aluminum handlebar is much stiffer than carbon. But is it really? Do you really sacrifice that much of comfort when using an aluminum handlebar? This is what I wanted to find out!
The test field is quite interesting. From one side we have a Spank Wing 12 Vibrocore aluminium handlebar (which I tested couple months ago) that has a Vibrocore foam in the tubes for reducing vibrations. We also have a bike fitters favourite Zipp Service Course SL-70 ergo handlebar that is something like a handlebar benchmark for many. Both of them are made from 7-series aluminium which is stiffer than a more popular 6-series aluminium. On the other hand, we have even more unique carbon contenders. First is a Coefficient Wave handlebar that has a very distinctive shape (more on that in an upcoming review) and for some reviewers, offers fantastic dampening properties when riding on drops. There is also a more renowned carbon handlebar in the test field: Ritchey WCS VentureMax with its uniquely shaped flared drops and very comfortable, flat tops (this handlebar I will also review in an upcoming article).
In that field, only Spank was in a different width (44 cm while the rest were 42 cm). Two of the tested handlebars (Spank and Ritchey) have a significant flare (12 and 24 degrees) while Zipp has only 4 degrees of flare and Wave even less than that. Zipp and Wave also have ovalized tops while Spank and Ritchey have very pronounced, flat tops area (which could influence the results recorded when riding on tops).
To make the difference more visible I used a benchmark bike with rigid Open U-turn GravelPlus fork, a 90 mm rigid stem (with the same amount of spacers below – 25 mm) and Rene Herse Barlow Pass 38c tires inflated to 40 psi (at back I used 30 PSI and a suspension seatpost to be sure that rear of the bike is not influencing the front end measurements that much). I also did not wrap the handlebars with bar tape (because I did not want the bar tape influence the results) but I was using my regular Giro gloves (mostly for safety – gloves provided more secure grip on naked handlebars). To my classic forest / fast gravel tests (vibrations measurement when riding on the hoods) I added also tops and drops measurement (but tops on a gravel route were measured not at 35 km/h but only 20 km/h – I always try to be as close to real life as possible with my tests and I am usually in a cruise mode when on tops).
The subjective observations
Before I will talk about the objective results I want to give you some subjective observations. First, there was a huge perceptible difference when trying to flex the carbon handlebar vs aluminium one. The stiffness of the aluminium handlebars that I tested was substantial and I was trying very hard to make them bend at all while carbon was bending easily (subjectively Wave was slightly more flexy than the Ritchey handlebar). The flex was most apparent when riding on drops but at the level of the hood, it was still very much perceptible. Then there is the famous road buzz taming properties of carbon. This, to be honest, I could not feel (like I could not feel the Vibrocore foam doing its work on an aluminium Spank handlebar). But, and I can’t deny that there is something in your head saying that carbon has to be better than aluminium so naturally, you can convince yourself that indeed there is somehow fewer vibrations.
The objective results
The first and most striking thing when looking at those results is that there is only a slight difference in terms of vibrations between aluminum and carbon handlebar. Honestly, I was thinking that there will be something like a 10% difference but in reality, it was more like 5-6% in the best-case scenario. When riding on hoods on a bumpy forest route there were some differences between tested handlebars but not between carbon and aluminum but more between straight and flared handlebars (both Spank and Ritchey performed slightly better which can suggest that rotating your hands can be somehow beneficial in terms of absorbing big bumps).
In the forest scenario, when riding on drops, Ritchey was the best, but again, we are talking about a 6% difference between the best and the worst handlebar. What surprised me was the differences when riding on tops. When you ride on tops, you put less weight on the front wheel and your arms are moving more freely but the higher the tops (the Wave case), the fewer weight on the wheel resulting in the more bouncy front wheel and objectively you register more vibrations (although in real life your arms are even more relaxed so those vibrations do not translate into more tiredness – more on that in my full review of Wave handlebar).
Moving on to the fast gravel ride. Here, which again surprised me, there was NO difference between tested handlebars when riding on hoods. Due to a very high level of measured vibrations I had to do 5 (not 3 as usually) test runs for each handlebar but when I calculated the average, all of the handlebars presented a very similar level of vibrations. Fortunately, drops brought many more variations in the results. Here both carbon handlebars were better, but again, by only a slight margin. When riding on tops at 20 km/h, Ritchey was again the best, but second was Spank handlebar (which may somehow prove that Vibrocore indeed is doing something, or, which is, in my opinion, a more probable explanation, flat tops are more beneficial for the overall comfort because the weight is more evenly distributed). Again, Wave handlebar due to the higher tops (because of the unique upward bend) was the worst but I believe that your arms are the most relaxed when riding on Wave tops so higher levels of vibrations do not translate into quicker tiredness in this case.
To sum up
Yes, the carbon handlebar indeed offers slightly more compliance but not even close to the levels you would subjectively guess just by riding them. The flex, that carbon handlebar offers, is beneficial but the level of compliance offered by much cheaper good aluminum handlebar is very similar and you don’t need to worry about damaging the carbon tubes (either by applying too much force when installing the handlebar or just by falling hard on the ground – which is a scenario that many of carbon handlebar owners are really scared off). These results also show that you should focus much more on the ergonomics of the handlebar than on the compliance in provides. And this will be my main topic on the upcoming reviews of Ritchey WCS VentureMax and Coefficient Wave handlebars. Stay tuned!