Shaft drive mountain bike

"malandro95" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I am kind of a newbie to cycling, but would like to get involved in
Mountain biking. I have been doing some research on bicycles and am
considering a shaft driven mountain bike.

Some of you might ask why I would even consider a shaft-driven bike
when the chain driven bikes have already proven themselves. Here is a
link that seems convincing to me:
http://www.dynamicbicycles.com/chainless/shaft_v_chain.php Let me know
if you can refute anything it says. I am most interested in having a
bike that won't leave grease on my pants so I can take it to work.

I think they are wrong about the efficiency. A chain driven bicycle is one
of the most efficient uses of energy ever invented, gears are not. Just
another gimmick in my opinion.

These bikes are aimed at people who are terrified of technology and
visible moving parts. Most of what they say on the site is blatantly
self-serving and silly. (Like the claim that their bikes are
particullarly good for people recovering from surgery). Internal gears
have their place (not for mountain biking though) but the shaft drive
is just a gimmick. Kind of reminds me of the "landrider" autoshifting
bikes on the infomerical.
Jeff T

malandro95 said:

I am kind of a newbie to cycling, but would like to get involved in
Mountain biking. I have been doing some research on bicycles and am
considering a shaft driven mountain bike.

That's a terrible idea. I'm no fan of derailleurs, but bicycle shaft
drives are not really robust enough for even gentle use. They combine
the tradeoffs inherent to internal gear hubs with those of drive shafts
*and* those of immature technology.

Quoted message said:

Some of you might ask why I would even consider a shaft-driven bike
when the chain driven bikes have already proven themselves. Here is

a

Quoted message said:

link that seems convincing to me:
http://www.dynamicbicycles.com/chainless/shaft_v_chain.php Let me

know

Quoted message said:

if you can refute anything it says.

Of the twelve points given, four are simply descriptive (numbers 1, 2,
8, and arguably 12). The others are either false or otherwise
deceptive. The efficiency claim they make for their shaft drive is
particularly laughable.

Quoted message said:

I am most interested in having a
bike that won't leave grease on my pants so I can take it to work.

If you want to combine this requirement with "mountain biking" as it is
generally understood, you'll need to use a Rohloff Speedhub and a
chainguard or chaincase. Other gearhubs have insufficient gearing
range for much off-road riding. And I wouldn't trust a bicycle drive
shaft to last a satisfactory amount of time in off-road use (or any
kind of riding, really).

Note that off-road motorcycles use chain drive, even though shaft-drive
motorcycles are common and reliable. Shaft-drive bicycles are neither
common nor, to my knowledge, reliable.

Quoted message said:

I have some concerns with shaft driven bikes though. Although, I

feel

Quoted message said:

confident with the Shimano brand, I'm not sure I like the looks of

the

Quoted message said:

gearing chart as shown on the bottom of this page:
http://www.dynamicbicycles.com/chainless/gearing.php The chart makes
it appear like I will be missing out on my lowest 2 and highest 3
gears. To you mountain bike pros, how will that affect my

performance

Quoted message said:

for trail riding?

A normal MTB has an overall gearing range of between 5:1 and 6.5:1,
while the Shimano Nexus 8 hub offers a range of slighly over 3:1. (The
"chart" on the link you furnished is woefully deceptive in this
regard.) This is a big difference. If you use a gearhub for off-road
riding, you will give up either low (less than 1:1) gearing, which will
limit your ability to climb and ride on soft surfaces; or you will give
up streetworthy high gearing.

For example, the Nexus 8 option with 1.5:1 ratio on the driveshaft
would offer a usefully low 21 inch low gear, but would give you a high
gear of 63 inches, good for a top speed of 16.5 mph at 90 pedal rpm.
That's not awful, but most folks would like to be able to ride faster
when conditions permit.

The Nexus 8 with a 2:1 driveshaft ration would offer a top gear of 84
inches, enough to maintain 22mph at 90 pedal rpm. But the low gear of
27.4 inches could limit your off-roading options somewhat.

The Rohloff Speedhub offers 5.26:1 range with 14 gears, but is
incompatible with the drive shafts you have referenced because it
requires a primary drive ratio of at least 2.35:1. There have been
toothed belt drive coversions for the Rohloff hub, but these require
special bike frames since a belt can 't be opened and reconnected like
a chain.

Accepting the gearing limitations imposed by a gearhub-equipped bike is
a livable compromise; I have several such bikes that work well for me
in city use. But I caution you that the shaft drive is not likely to
be all that you hope for when it comes to reliability. If you have
trouble with it, it's unlikely that you'll be able to get qualified
repair and service at a bike shop. You may not even be able to buy
spare parts for it. If you find it unsatisfactory, you will be stuck
with a bike that can't be retrofitted with an ordinary drivetrain.

The Chainless Bicycles site says: "It has been tested at over 1000
lbs./in of torque - more than 4 times the pressure exerted by an
average rider under normal conditions." But a rider standing to
pedal-- a very common situation in off-road riding-- places his entire
weight on a 7 inch crank, and can add to this by pulling at the
handlebars. What is your weight times seven? And how does that compare
to the 1000 lbf-in at which Chainless Bicycles claim to have tested
their drive shaft? And can you even trust that number in light of the
wealth of erroneous and misleading information they provide?

Chalo Colina

Quoted message said:

Note that off-road motorcycles use chain drive, even though shaft-drive
motorcycles are common and reliable. Shaft-drive bicycles are neither
common nor, to my knowledge, reliable.

I saw a motorcycle the other day that used a toothed drive belt
instead of a chain. That would seem to be a better option for an
internal hub bike without grease than a drive shaft.

Though a chain guard the separates your pants from the chain, and the
chain from a lot of grit, would seem simpler still.

dewatf.

Jeff said:

Internal gears have their place (not for mountain biking though)

Really? Why not?

dewatf said:

Chalo said:

Note that off-road motorcycles use chain drive, even
though shaft-drive motorcycles are common and reliable.
Shaft-drive bicycles are neither common nor, to my
knowledge, reliable.

I saw a motorcycle the other day that used a toothed drive belt
instead of a chain. That would seem to be a better option for an
internal hub bike without grease than a drive shaft.

All Harley-Davidsons use belt drive. It has distinct maintenance
advantages over a chain, and weight and efficiency advantages over a
drive shaft.

There are tradeoffs, though. One of the things I wrote in my earlier
post was

Quoted message said:

Quoted message said:

There have been toothed belt drive conversions for the
Rohloff hub, but these require special bike frames since
a belt can't be opened and reconnected like a chain.

Drive belts also have the disadvantage of being a fixed length, with
any change in gearing or chainstay length requiring a different size
belt.

Quoted message said:

Though a chain guard the separates your pants from the chain, and the
chain from a lot of grit, would seem simpler still.

That seems to be the preferred solution for low-maintenance bikes in
European countries.

Chalo Colina

malandro95 said:

I am kind of a newbie to cycling, but would like to get involved in
Mountain biking. I have been doing some research on bicycles and am
considering a shaft driven mountain bike.

Some of you might ask why I would even consider a shaft-driven bike
when the chain driven bikes have already proven themselves. Here is a
link that seems convincing to me:
http://www.dynamicbicycles.com/chainless/shaft_v_chain.php Let me know
if you can refute anything it says. I am most interested in having a
bike that won't leave grease on my pants so I can take it to work.

Then protect your pants. I use a simple band that holds my pants leg
near my shin, away from the chain.

No problems are really solved by the shaft drive, and it causes other
problems. There are definite efficiency losses from the gears -- much
more so than with a chain. There is a reason chain drives have survived
so long. Primarily it is the efficiency. Remember that a bike/rider is
(compared to engine-driven machines) underpowered, and a 20% loss of
efficiency is a serious issue.

The comparison chart on the site above is, frankly, [censored].

1) Gear movement is no "rougher" with a derailleur system than with an
internal gear system. I have both.

2) Maintenance: They fail to mention the difficulties you will have the
first time you have to change a flat on the rear wheel.

3) There is no problem with "fully exposed" derailleurs. I have some
that are 30 years old. Durable enough?

4) The alignment of a shaft drive system has to be critical. Wheels can
get knocked out of alignment whether the drive system be chain or shaft.
Chains are more forgiving of such misalignment than shafts.

5) The "ground clearance" issue is totally bogus. That 8" clearance is
not between wheels of a car, it is from the bottom of the jockey wheels to
the ground -- and this is adjacent to the rear wheel. It's not as if
there were some rock that would be likely to hit the derailleur, but you
would not hit with the rear wheel, or your pedals, etc.

6) Shaft drives are not anywhere near that efficient, nor are chain
drives that inefficient. In addition, the SRAM internal gears have
serious inefficiency of their own.

7) Why does 8-speed have the "range" of 20 gears? This is meaningless,
since the range of a derailleur system can be changed easily by replacing
a cassette, or chainring. Changing the range of an internal gear system
is impossible.

8) Noise. Sorry, the internal gear systems are noisier than derailleur
systems.

9) No grease? How do they lubricate the gears? Sure, chains are greasy,
but so are the exposed ends of a shaft drive. If they are not exposed,
it is because they have a cover. Chain-guards do exactly the same thing.

Quoted message said:

http://www.dynamicbicycles.com/chainless/gearing.php The chart makes

it

Quoted message said:

appear like I will be missing out on my lowest 2 and highest 3 gears. To
you mountain bike pros, how will that affect my performance for trail
riding?

I personally don't think most recreational riders miss much by giving up
the very high gears. They do miss the very low ones.

--

David L. Johnson

__o | Become MicroSoft-free forever. Ask me how.
_`\(,_ |
(_)/ (_) |

Quoted message said:

Jeff said:

Internal gears have their place (not for mountain biking though)

Really? Why not?

(The following comments apply to gearhubs other than the Rohloff
Speedhub. The Rohloff is not only suited to MTB use, it is intended
for MTBs.)

Internal-gear hubs have a gearing range too limited for the breadth of
typical MTB conditions.

If geared down sufficiently for off-road climbing, they are subject to
damaging geartrain torques.

They will not usually shift while under heavy pedal load. If a shift
is made while under heavy load, it will be executed at the moment the
load is eased.

Chalo Colina