Re: [CR]hub gear and derailleur efficiency.

(Example: Production Builders:Cinelli)

In-Reply-To: <20050803124351.790661F5@dm21.mta.everyone.net>
References: <20050803124351.790661F5@dm21.mta.everyone.net>
From: "Bob Reid" <robertrreid@tiscali.co.uk>
Subject: Re: [CR]hub gear and derailleur efficiency.
Date: Wed, 3 Aug 2005 23:58:56 +0000
To: Classic Cycling List <classicrendezvous@bikelist.org>


No sure this put's anything to bed without the full test details showing the data he used and how it was obtained for this massive speed drop of 0.37 miles per hour. Boy that must have been disappointing when those results came out so close. Sounds like another of these back-of-a-fag-packet (Alec Issigonis used a paper napkin) calculations wrapped around in pseudo science... In reality unless everyone rides hills at a constant effort all of the time, at a 100% of your available power, it would be possible to increase your cadence to get up the hill and negate the 0.6 Km/H speed drop - your engine however would wear out sooner !

Bob Reid Stonehaven Scotland.

On 3 Aug 2005, at 19:43, Michael Toohey wrote:
> I hope the following quote from cycling's inveterate empirical
> tester puts this debate to bed. F.B. uses a Shimano 7 speed for an
> example, but the figures are applicable to Sturmey hubs; look for
> the graphs in the 3rd edition of Bicycle Science for more detail.
>
> "...suppose that you are an average, one eighth horse power 72.5kg
> cyclist. You can pedal up a four percent grade in a 31-inch low
> gear with a 96 percent efficient derailleur gear train at 8.8 km/h
> at a cadence of 60.
> If you pedal up the same hill using a seven speed hub gear, the
> efficiency is about 90 per cent. Since you are horsepower-limited,
> your cadence will drop to 56 and you will slow down to 8.2km/h.
> So, hub gears are a bit less efficient and while you lose in
> efficiency, you gain a bit in easier maintainence and longer
> product life."
>
> Frank Berto, Hub gears v Derailleurs, Australian Cyclist, Sept-Oct,
> 2004
>
> Michael Toohey (who loves his FC, regardless)
> Rangiora
> New Zealand.
>
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