shaft drive ?

On page 13 of the Sunday Times business section yesterday there was a
picture of a japanese minister riding a bicycle with a shaft drive ! Has
anyone seen these ? A good idea ?

maf

"maf" wrote in message
...
On page 13 of the Sunday Times business section yesterday there was a
picture of a japanese minister riding a bicycle with a shaft drive ! Has
anyone seen these ? A good idea ?


Yes -- seen similar.

Generally less efficient than a conventional chain -- but potentially a
'clean' drive with less bits to grab your Gucci suit -- not that many cycle
in their Gucci suit!!

T

Ian wrote:

There was an article about them in the last edition of Velovision.

http://www.velovision.co.uk/cgi-bin/...l?storynum=507

More than that, it's a full test of an actual example you can swap for
money in the UK.

Pete (still waiting for the new VV to land on his doormat).
--
Peter Clinch University of Dundee
Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

maf wrote:
On page 13 of the Sunday Times business section yesterday there was a
picture of a japanese minister riding a bicycle with a shaft drive !
Has anyone seen these ? A good idea ?

maf

Probably a Bridgestone or Panasonic neither of which AFAIK has been sold
outside Japan. You can find an example of a Bridgestone one at
http://www.bscycle.co.jp/catalog/fol...ansit-scx.html


There was a range of UK shaft drive bikes on show at the York Rally this
year. Rode one round the compound and it seemed OKish but it was not really
possible to judge much in the circumstances.

Tony

--
"If you tell the truth you don't have to remember anything."
Mark Twain

maf writes:

On page 13 of the Sunday Times business section yesterday there was a
picture of a japanese minister riding a bicycle with a shaft drive !
Has anyone seen these ? A good idea ?

Frankly, no.

With shaft drive you have to have two sets of bevel gears each turning
the drive through approximately ninety degrees. The efficiency losses
in the two gearboxes are much greater than the losses in chain drive,
and that's before you start getting into variable speed.

The gears also have to be relatively small so the forces on the teeth
are extremely high, which means wear is likly to be high. Furthermore,
extracting the rear wheel is going to be a lot more complex, because
the exact positioning of the gears is critical.

The deraileur gear system may seem incredibly crude. It _is_
incredibly crude, and the exposed chain does suffer from dirt, grit,
and loss of lubricant. But in terms of energy transfer it is
exceptionally efficient, and its very crudity makes it relatively
tolerant of slight variations in rear wheel position, making hand
assembly and disassembly unproblematic.

There are a nujmber of manufacturers of shaft drive bikes around, some
of them UK based. However in my opinion these machines are more or
less a gimmick.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

Anagram: I'm soon broke.

In article ,
says...
Ian wrote:

There was an article about them in the last edition of Velovision.

http://www.velovision.co.uk/cgi-bin/...l?storynum=507

More than that, it's a full test of an actual example you can swap for
money in the UK.

I was chatting to a bloke on a train a few months ago---having a
Brompton always gets people talking---and he had just bought his wife a
shaft-driven bike. He and she seemed quite pleased with it but at that
time I think it was brand new. If I bump into him again I'll ask how
she's getting along with it.

Pete (still waiting for the new VV to land on his doormat).

Mine landed at the weekend. As usual it is a great read.

Colin

Simon Brooke wrote:

Furthermore,
extracting the rear wheel is going to be a lot more complex, because
the exact positioning of the gears is critical.

The deraileur gear system may seem incredibly crude. It _is_
incredibly crude, and the exposed chain does suffer from dirt, grit,
and loss of lubricant. But in terms of energy transfer it is
exceptionally efficient, and its very crudity makes it relatively
tolerant of slight variations in rear wheel position, making hand
assembly and disassembly unproblematic.

Really? I have owned both shaft and chain driven motorbikes and the
shaft drive bikes have been implicity themselves to remove the rear
wheel from , with ( from memory) only one bolt needing to be removed to
enable to rear wheel to be lifted off. As to the energy transfer the
efficiency of a chain is only there when it is new, as soon as it
starts to suffer from "dirt, grit, and loss of lubricant." plus the wear
from the above the efficiency drops, whereas the shaft has the same
values almost forever.


--
Marc
Stickers,decals,membership,cards, T shirts, signs etc
for clubs and associations of all types.
http://www.jaceeprint.demon.co.uk/

Simon Brooke wrote:

The deraileur gear system may seem incredibly crude. It _is_
incredibly crude, and the exposed chain does suffer from dirt, grit,
and loss of lubricant. But in terms of energy transfer it is
exceptionally efficient, and its very crudity makes it relatively
tolerant of slight variations in rear wheel position, making hand
assembly and disassembly unproblematic.

Really? I have owned both shaft and chain driven motorbikes and the
shaft drive bikes have been implicity themselves to remove the rear
wheel from , with ( from memory) only one bolt needing to be removed to
enable to rear wheel to be lifted off. As to the energy transfer the
efficiency of a chain is only there when it is new, as soon as it
starts to suffer from "dirt, grit, and loss of lubricant." plus the wear
from the above the efficiency drops, whereas the shaft has the same
values almost forever.

Uhhhmmmm... no. See recent thread on rct for detailed discussion and
actual measurements. An end-of-life, worn out, filthy, gritty,
underlubricated chain is _still_ more efficient than a brand new shaft
drive. On a motorbike this does not matter because you can just add
more horsepower at the engine end. On a pedal cycle you cannot do this.

I'm willing to accept the power loss theory, but you still haven't
justified your assembly bias.

On Mon, 15 Sep 2003 10:21:23 +0100, "Tony Raven"
wrote:

There was a range of UK shaft drive bikes on show at the York Rally this
year. Rode one round the compound and it seemed OKish but it was not really
possible to judge much in the circumstances.


David Duffield was talking in today's Vuelta coverage about Rover, the
car company. Amongst other things, he said that an early tricycle was
shaft driven and that the world's first differential was invented for
the trike. Apparantly, its design was exactly the same as those still
used in rear wheel drive cars today.

James

--
"Sorry mate, I didn't see you" is not a satisfactory excuse.

maf wrote:
On page 13 of the Sunday Times business section yesterday there was a
picture of a japanese minister riding a bicycle with a shaft drive !
Has anyone seen these ? A good idea ?


My LBS had one in for repair a few weeks ago - broken axle on the three
speed. It was in ther for quite a while while they hunted down a longer
than standard axle for it.

--
Andrew Pattle