[CR]Hub gear vs. derailleur efficiency

(Example: Humor:John Pergolizzi)

Date: Mon, 10 May 2004 16:21:19 -0700
To: classicrendezvous@bikelist.org
From: "Jan Heine" <heine93@earthlink.net>
Subject: [CR]Hub gear vs. derailleur efficiency

Even at the risk of offending Anglophiles here - the question of hub gear vs. derailleur efficiency appears to have been settled. In Cycle History 12 (Proceedings of the International Bicycle History Conference), available from Vanderplas, Frank Berto and Chester Kyle did some pretty exhaustive tests.

They found that derailleurs are more efficient than 3-speed hub gears, especially at higher loads. For light loads of 100 watts, it already was a difference of 2%. The other problem is that hub gears are least efficient in the indirect highest gear. The intermediate gear equals that of a derailleur (planetaries are locked up, after all). But for racing, wouldn't you be in the least efficient gear most of the time?

According to their tests, hub gear efficiency depends on the quality of manufacture: The Rohloff hubs with ball bearings were not much less efficient than 7-speed hubs despite their many more gears inside). Older oil-lubricated hubs were better than brand-new grease-lubed ones.

Finally, chainline does not matter - at least with modern chains. In fact, Velocio already published that in 1919. He used a floating cog on the rear and found that it would not stay in perfect alignment - clearly, there was no incentive for it to do so. (The Velocio isn't in the Cycle History article.)

They also found that cogs smaller than 15 markedly decrease efficiency. The poor efficiency of small cogs already was stated by Daniel Rebour in the 1960s, when 13 tooth cogs first came about. (Rebour isn't in the Cycle History article.)

Similar results regarding hub gear vs. derailleurs came from the real-life testbed of the Poly de Chanteloup hillclimb race (not in Cycle History article, but will be covered in an upcoming issue of VBQ). In its early years, this race was intended to show whether variable gearing was advantageous on a hilly course, and if yes, which system was best. In the early years, you find a lot of hub gears, but also flip-flop rear wheels. After the mid-1920s, no winner used anything but derailleur gears.

Of course, this assumes that the pros used what worked best, rather than what they were paid to use. Later, randonneurs and mixed tandem randonneurs were allowed, and they, too, all used derailleurs, even the pure amateurs, who rode their personal bikes. Of course, by then the French cycling culture favored derailleurs...

I know there are numerous advantages to hub gears, but mechanical efficiency does not appear one of them.

(BTW, Fig. 11.16 in said article does not appear to back up their claims. I asked Frank Berto about this and am awaiting his response.)

No connection to Vanderplas Publishing, except they advertise in VBQ.

--
Jan Heine, Seattle
Editor/Publisher
Vintage Bicycle Quarterly
http://www.mindspring.com/~heine/bikesite/bikesite/