My present bicycle is a year 2005 Trek 2100WSD 47cm with Bontrager Race 650C wheels and Ultegra 9-speed cassette. Comparing this bicycle to several others which I've ridden over time, in particular the new Trek Domane, it feels like my old 2100's freehub is more efficient - the bicycle just wants to go faster coasting downhill. It's also very quiet compared to most others.
In general, noise = mechanical energy, and noisier = more energy loss to the freehub action while not pedaling. But of course there's nothing general about comparing one specific freehub to another one, which is why I'm here today asking you for your advice!
I recently rented and rode several hundred kilometres on a 2013 Trek Domane 5.9, with Bontrager Race Lite wheels and Ultegra 10-speed cassette, and I've just started the ordering process to buy a 2014 Trek Domane 5.2 with Bontrager Race wheels and Ultegra 6800 11-speed cassette. The 2013 Race Lite rear wheel's freehub is noisy, and coasting downhill without pedaling I really feel that the freehub creates noticeable resistance. (I also recently rode a Scott S20, and similarly the freehub was very loud and the resistance it created was noticeable).
I just returned today from a ride on my old Trek 2100 with its quiet freehub, and I'd swear that it just rolls downhill faster.
There's at least one not-apples-to-apples comparison here - my Trek 2100 has 650C wheels, and all of these other bicycles that I'm commenting about have 700C wheels. If nothing else, the inertia of the larger wheels is surely greater, which would mean that the larger wheels would accelerate more slowly. But on a long coasting descent, the speeds which the bicycle would routinely reach shouldn't be affected by the wheel size and inertia, because slower acceleration is still acceleration. But it would be affected by the efficiency of the freehub, which is constantly (and at higher speeds, more) bleeding off energy/speed.
So here's the question: Does anyone know the details about the efficiency of the 2005 Bontrager Race wheels' freehub - Ultegra 9-speed as came on my 2005 Trek 2100WSD 47cm with 650C wheels, and how to compare that to the efficiency of the modern 2014 Bontrager Race wheels' freehub - Ultegra 6800 11-speed? .. and suggestions on how I might make a brand new 2014 Domane 5.2's freehub quieter and more efficient?
thanks, and I apologise in advance for any obvious boneheaded misunderstandings I've demonstrated in asking the question here today. (Plus, please don't respond "real riders should always be pedaling, so the freehub's efficiency shouldn't be that important". So, I'm not a "real" rider. Fine).
Jay