Continuously-variable transmission box in Honda MTB

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

Quoted message said:

Did anyone see the latest issue of _Mountain Bike Action_ featuring
Honda's mountain bike and CVT drivetrain? Any comments?

Van
--
Van Bagnol / v b a g n o l at earthlink dot net / c r l at bagnol dot com
...enjoys - Theatre / Windsurfing / Skydiving / Mountain Biking
...feels - "Parang lumalakad ako sa loob ng paniginip"
...thinks - "An Error is Not a Mistake ... Unless You Refuse to Correct

It"

looks heavier than a regular drivetrain

Michael

Michael Paul said:

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

Quoted message said:

Did anyone see the latest issue of _Mountain Bike Action_ featuring
Honda's mountain bike and CVT drivetrain? Any comments?

looks heavier than a regular drivetrain

Michael

Downhill rigs looking more and more like motorcross every year.... sure does
look heavy.

A few car manufacturers have made models with CVT boxes over the years, i
think DAF was the first, but they were riddled with problems, related to
belt slippage and the requirement for very frequent maintainance and such
things. I think i read that Audi have made a CVT system which eliminates
belts so maybe things are improving, Even so, i suspect that Honda bike
wouldn't be good for much more than race runs, wouldn't go for long without
maintenance i bet.

Did anyone read about the technicalities of the Honda box? Is it belt/roller
or some sort of expanding sprocket and chain?

--
Mark

Van Bagnol said:

Did anyone see the latest issue of _Mountain Bike Action_ featuring
Honda's mountain bike and CVT drivetrain? Any comments?

Van

Read it at the library. Looks fat and inefficient (I should know).
Hopeless concept as an XC bike. Chain drive is just too efficient.

Shawn

On Wed, 12 May 2004 17:08:24 +0100, "Mark \(UK\)"

may have said:

Michael Paul said:

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

Quoted message said:

Did anyone see the latest issue of _Mountain Bike Action_ featuring
Honda's mountain bike and CVT drivetrain? Any comments?

looks heavier than a regular drivetrain

Michael

A few car manufacturers have made models with CVT boxes over the years, i
think DAF was the first, but they were riddled with problems, related to
belt slippage and the requirement for very frequent maintainance and such
things. I think i read that Audi have made a CVT system which eliminates
belts so maybe things are improving,

If Audi's making it, don't expect it to be worth owning. They've had
to go over to a 100,000-mile drivetrain warranty just to get people to
buy their cars in the US, and their resale value on out-of-warranty
units still isn't as high proportionately as most other makes. The
only car that depreciates faster, in my experience, is Daewoo...and
that's because GM took Daewoo off the North American market.

Quoted message said:

Even so, i suspect that Honda bike
wouldn't be good for much more than race runs, wouldn't go for long without
maintenance i bet.

Honda probably figures that there's a market for wierd and unusual
tech. I suspect that they will not sell many.

Quoted message said:

Did anyone read about the technicalities of the Honda box? Is it belt/roller
or some sort of expanding sprocket and chain?

Only the former works in practice; variable-diameter pulleys drive a
heavy belt. Sliding-cone-drive setups have been tried in the lab, and
they always cause some fool at Popular Mechanics to write it up as The
Next Really Great Thing That Will Be In Every Car In A Few Years.
Oddly enough, they never make it to market. CVTs of the belt type are
common in ATVs and LPCs (light personnel carriers; a glorified term
for "golf cart"😉 and are regarded and durable and reliable in most
applications there. I don't know how Honda has adapted the concept to
the relatively low velocities of a bicycle, but apparently they must
have done so.

Here's a picture of the bike:

http://world.honda.com/news/2003/2030203.html

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

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

Quoted message said:

On Wed, 12 May 2004 17:08:24 +0100, "Mark \(UK\)"

may have said:

Michael Paul said:

"Van Bagnol" <[email hidden]> wrote in message
news:[email hidden]...
> Did anyone see the latest issue of _Mountain Bike Action_ featuring
> Honda's mountain bike and CVT drivetrain? Any comments?
>
looks heavier than a regular drivetrain

Quoted message said:

Even so, i suspect that Honda bike
wouldn't be good for much more than race runs, wouldn't go for long without
maintenance i bet.

Honda probably figures that there's a market for wierd and unusual
tech. I suspect that they will not sell many.

Honda sometimes like to be the Sony of the vehicle market.

Quoted message said:

Quoted message said:

Did anyone read about the technicalities of the Honda box? Is it belt/roller
or some sort of expanding sprocket and chain?

Only the former works in practice; variable-diameter pulleys drive a
heavy belt. Sliding-cone-drive setups have been tried in the lab, and
they always cause some fool at Popular Mechanics to write it up as The
Next Really Great Thing That Will Be In Every Car In A Few Years.
Oddly enough, they never make it to market. CVTs of the belt type are
common in ATVs and LPCs (light personnel carriers; a glorified term
for "golf cart"😉 and are regarded and durable and reliable in most
applications there. I don't know how Honda has adapted the concept to
the relatively low velocities of a bicycle, but apparently they must
have done so.

Last time we had the belt-drive-for-bikes discussion in here, there was a
general consensus that it couldn't be done at all. Not reliably anyway.
--
Mark South
Citizen of the World, Denizen of the Net
<<Tiens! Ce poulet a une grenade!>>

On Wed, 12 May 2004 22:00:02 +0200, "Mark South"

may have said:

Last time we had the belt-drive-for-bikes discussion in here, there was a
general consensus that it couldn't be done at all. Not reliably anyway.

I'd have argued that myself if it wasn't for the fact that it appears
that Honda may have come up with a kluge that at least permits the
bike to move forward. How well it works is, of course unanswered, and
I am skeptical about that subject. Even if they have made it work
reasonably acceptably, though, I don't see it displacing the der
setup anytime soon, since I can't see any way for it to be as
efficient...and the limiting factor in bike performance is the
powerplant, so drivetrain losses just aren't going to be tolerable to
a lot of folks.

The photo of the Honda bicycle shows a unit that bears more than a
passing resemblance to a motorcycle. I doubt that this is mere
coincidence. OTOH, as far as I can see, Honda doesn't have any
marketing channels set up to get this to the places where it might
sell if it really is a worthwhile piece of tech. In my opinion, that
fact is a big hint that this is a showcase item with no mass
production planned. Honda-branded bikes are sold at K-Mart, however
as far as I know those are strictly pasted-on-label units rather than
a product that actually emerged from Honda's plants. A bike with a
CVT would not be a logical thing to market through KMart unless it was
going to be *really* cheap.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

"Mark South" <[email hidden]> wrote

Quoted message said:

Last time we had the belt-drive-for-bikes discussion in here, there was a
general consensus that it couldn't be done at all. Not reliably anyway.

Belts can be done, but only if you include a Rohloff SpeedHub. And maybe a
Mountain Drive BB.

http://www.rohloff.de
http://www.schlumpf.ch/md_engl.htm

pete

Shawn Curry said:

Looks fat and inefficient (I should know).
Hopeless concept as an XC bike. Chain drive is just too efficient.

You miss the point. It was not an exercise intended to result in a
better bicycle, it was an exercise intended to result in better motor
company engineers.

That said, derailleur systems are primitive, unreliable, inelegant
junk that owe their existence to the fact that they are cheap as dirt
to manufacture. If Brand S had invested the kind of engineering
resources in, say, internal gear hubs that they have sunk into
prolonging the heyday of derailleur systems, we'd already have better
options available.

Any motor vehicle drivetrain, for example, that did as thorough a job
of rapid self-destruction as a bike derailleur system would go down in
legend as a laughingstock. The fact that most derialleur bikes are
toys or fetish objects rather than regular transportation allows the
continued prevalence of multi-speed transmissions that self-digest in
a few thousand miles and demand constant maintenance.

Chalo Colina

Chalo said:

Shawn Curry said:

Looks fat and inefficient (I should know).
Hopeless concept as an XC bike. Chain drive is just too efficient.

You miss the point. It was not an exercise intended to result in a
better bicycle, it was an exercise intended to result in better motor
company engineers.

I was stating facts, not making a "point". Nevertheless, I think you
missed the point. It was an exercise to improve the bottom line, to
show off Honda to a crowd that thinks SUV and Subaru.

Quoted message said:

That said, derailleur systems are primitive, unreliable, inelegant
junk that owe their existence to the fact that they are cheap as dirt
to manufacture. If Brand S had invested the kind of engineering
resources in, say, internal gear hubs that they have sunk into
prolonging the heyday of derailleur systems, we'd already have better
options available.

Any motor vehicle drivetrain, for example, that did as thorough a job
of rapid self-destruction as a bike derailleur system would go down in
legend as a laughingstock. The fact that most derialleur bikes are
toys or fetish objects rather than regular transportation allows the
continued prevalence of multi-speed transmissions that self-digest in
a few thousand miles and demand constant maintenance.

Chalo Colina

I think most consumers and manufacturers look at it differently. The
wildly enthusiastic commuter might ride a dozen miles each way to work
etc. 120 miles a week, 6000 miles/yr (remember, this is a very skewed
population on these NGs). Oil the chain twice a month and replace the
derailleurs, chain, etc twice a year. $300/year (you're not gonna buy
new XTR replacement parts are you?). Big deal. A VERY efficient car
would cost that much in gas alone. If they're like a lot of us they buy
a new bike every few years. They're super hot ride from three years ago
gets relegated to commuter status. The cost of acquiring the bike
itself only amounts to the lost sale value of the outdated bike (I'm not
considering the Seven Duo crowd here). S/he's saving big bucks! The
market pressure to develop a new efficient transmission just isn't
there. I commuted on a fixie quite a few years ago-costs even less. :-)

Shawn

Quoted message said:

Oil the chain twice a month and replace the
derailleurs, chain, etc twice a year.

I agree with Chalo here. Can you imagine telling "Suzie SUV" she has to oil
her drivetrain every other week, and would have to replace her transmission
every oil change?

I and almost everyone I know carries a chain tool out of necessity.

Compared to automobiles and almost all other vehicles, bicycle drivetrains
are [censored].

Werehatrack said:

Even if they have made it work
reasonably acceptably, though, I don't see it displacing the der
setup anytime soon, since I can't see any way for it to be as
efficient...and the limiting factor in bike performance is the
powerplant, so drivetrain losses just aren't going to be tolerable to
a lot of folks.

Honda haven't published drivetrain losses for the CVT box, but I imagine it
would operate something like a seamless Sturmey Archer hub. You'd always be
pedalling at the right cadence which is going to help efficiency, the
transmission can be protected from [censored] and dirt, and you're not dragging
the chain through funny angles and idler gears on a derailleur. Might
actually be more efficient. It looks as if there's still a chain doing the
actual drive from the cranks to the back wheel. That said, they're racing it
as a DH bike, so pedalling might not be *that* important.

John Harlow said:

Quoted message said:

Oil the chain twice a month and replace the
derailleurs, chain, etc twice a year.

I agree with Chalo here. Can you imagine telling "Suzie SUV" she has to oil
her drivetrain every other week, and would have to replace her transmission
every oil change?

When was the last time you heard "Suzie SUV" say "I'm not going to
commute by bike, there's too much maintenance involved." LOL
You may get SS there to commute two miles on a cruiser now and then.
Oil the chain once a year (Biff Bimmer can handle that).

Quoted message said:

I and almost everyone I know carries a chain tool out of necessity.

For Commuting?

John Harlow said:

Quoted message said:

Oil the chain twice a month and replace the
derailleurs, chain, etc twice a year.

Quoted message said:

I agree with Chalo here. Can you imagine telling "Suzie SUV" she has to oil
her drivetrain every other week, and would have to replace her transmission
every oil change?

"Suzie SUV" takes her car in for oil changes; she could take
her bike to the LBS. She also doesn't commute by bike because
she's scared of traffic, not because maintenance is an issue.
The average commuter or non-enthusiast is more worried about
flats than drivetrain maintenance anyway.

Quoted message said:

I and almost everyone I know carries a chain tool out of necessity.

For MTBing, at least, because you can't improvise a chain tool
and who wants to be stuck out in the middle of nowhere.
I assume people who go offroading in 4x4s also carry a tool kit.

Quoted message said:

Compared to automobiles and almost all other vehicles, bicycle drivetrains
are [censored].

Bicycles weigh about one-tenth their payload capacity. The same
cannot be said for automobiles. If cars were like bicycles, a
Toyota Tercel would be able to tow a horse trailer.
If you would accept a pricey forty pound rigid bike, it could
probably be made bulletproof. My guess is you'd rather ride the
twenty pounder (I would).

In article <[email hidden]>,

Mark \(UK\) said:

A few car manufacturers have made models with CVT boxes over the years, i
think DAF was the first, but they were riddled with problems, related to
belt slippage and the requirement for very frequent maintainance and such
things. I think i read that Audi have made a CVT system which eliminates
belts so maybe things are improving, Even so, i suspect that Honda bike
wouldn't be good for much more than race runs, wouldn't go for long without
maintenance i bet.

Did anyone read about the technicalities of the Honda box? Is it belt/roller
or some sort of expanding sprocket and chain?

It appears to be a variable-geometry reciprocating ratchet. It uses no
belts or chains, except for the drive chain from the transmission box to
the rear wheel (as in a single-speed). It does have gears, though.

The basic mechanical transmission is this: Step up pedal gearing to 11:1
or thereabouts; convert circular motion to reciprocating; use the
reciprocating motion to drive a ratchet; ratchet converts motion back to
circular; circular chainring pulls chain; chain turns cog at rear hub.
The variable transmission is in the geometry by which the reciprocating
arm engages the pawls. Gear range is about 3:1, the same as an 11-33
tooth cassette. One key feature is a scalloped or hypocycloid gear that
smooths the reciprocating stroke back into steady circular motion.

Frictional losses are minimized by the liberal use of needle bearings,
and weight is minimized by encasing the tranny in a carbon-fiber shell
with an aluminum "skeleton" for load-bearing. (The entire mech is bathed
in transmission fluid.) The article admits that weight and transmission
efficiency don't match conventional derailleurs, but points out the
advantage of CVT available at all times, even when under load, and that
the mechanism is sealed from the elements, reducing chainsuck. Also the
fixed front-rear cog sizes allow for rear suspension travel without
pedal feedback.

I only thumbed through the article at the magazine stand but that's what
I remember.

Van
--
Van Bagnol / v b a g n o l at earthlink dot net / c r l at bagnol dot com
....enjoys - Theatre / Windsurfing / Skydiving / Mountain Biking
....feels - "Parang lumalakad ako sa loob ng paniginip"
....thinks - "An Error is Not a Mistake ... Unless You Refuse to Correct It"

In article <40a42976$1@darkstar>,

Benjamin Weiner said:

John Harlow said:

Quoted message said:

Oil the chain twice a month and replace the
derailleurs, chain, etc twice a year.

Quoted message said:

I agree with Chalo here. Can you imagine telling "Suzie SUV" she has to oil
her drivetrain every other week, and would have to replace her transmission
every oil change?

"Suzie SUV" takes her car in for oil changes; she could take
her bike to the LBS. She also doesn't commute by bike because
she's scared of traffic, not because maintenance is an issue.

She doesn't commute by bike because she doesn't want to put up a sweat
going to work, and bringing the kids to soccer practice and hauling
groceries is a lot of pedaling.

But the article did state that Honda has some form of CVT in its
electric-gas hybrid automobile, although I don't know what mech it uses.

Van
--
Van Bagnol / v b a g n o l at earthlink dot net / c r l at bagnol dot com
....enjoys - Theatre / Windsurfing / Skydiving / Mountain Biking
....feels - "Parang lumalakad ako sa loob ng paniginip"
....thinks - "An Error is Not a Mistake ... Unless You Refuse to Correct It"

Chalo said:

That said, derailleur systems are primitive, unreliable, inelegant
junk that owe their existence to the fact that they are cheap as dirt
to manufacture.

As if price doesn't count. The onus is on other systems to compete on price-value-performance,
_which they have not done_. That pretty much speaks for itself.

Quoted message said:

If Brand S had invested the kind of engineering
resources in, say, internal gear hubs that they have sunk into
prolonging the heyday of derailleur systems, we'd already have better
options available.

Right. If only _all_ bicycle designers in history had been as far-sighted and intelligent as you,
they could have made a killing on a superior system that works better and costs less. There sure
are a lot of stupid people "out there." They just don't know how to act in their own self-interest
and put a superior system on the market... sheesh!

Quoted message said:

Any motor vehicle drivetrain, for example, that did as thorough a job
of rapid self-destruction as a bike derailleur system would go down in
legend as a laughingstock.

There is nothing inherently wrong in the balance of tradeoffs of accepting an occasional chain
replacement, a less often cog replacement, a still less often ring replacement, and less often
derailleur replacement. A new chain is $10, and the time taken to earn the funds to replace it and
the time taken to install are truly quite small, especially in light of the amount of time the chain
actually gets used.

The onus is on other systems to compete on the balance of tradeoffs. They haven't, so they just
aren't around as much.

Quoted message said:

The fact that most derialleur bikes are
toys or fetish objects rather than regular transportation allows the
continued prevalence of multi-speed transmissions that self-digest in
a few thousand miles and demand constant maintenance.

Ridiculous. It has nothing to do with "the service mode they operate within." A chain is a chain
and wears out whether one is racing, sight-seeing, or commuting. The balance of tradeoffs continues
to select the current systems in the marketplace; drivetrain wear is part of that tradeoff. The
onus is on other the systems to overcome their own disadvantages and win on the balance of tradeoffs.

Besides, "constant maintenance is untrue." I do nearly zero maintenance on my drivetrains in
between chain changes. If it squeaks, I'll lube it in < 1 min, otherwise I just ride. It is like
complaining that the car keeps running out of gas.

Benjamin Weiner said:

Bicycles weigh about one-tenth their payload capacity. The same
cannot be said for automobiles. If cars were like bicycles, a
Toyota Tercel would be able to tow a horse trailer.

Not if you count the engine! If cars were like bikes with riders,
you'd be lucky if that Tercel could carry more than one passenger
without resorting to a trailer.

A better comparison between bike weight and gross weight would be to
compare against just an auto transmission, driveshaft, and wheels.
Then the bike doesn't seem like such an outstanding mechanical
performer.

Quoted message said:

If you would accept a pricey forty pound rigid bike, it could
probably be made bulletproof. My guess is you'd rather ride the
twenty pounder (I would).

My best bikes weigh close to 40 lbs. They are the ones that are
sufficiently rigid, have safe and reliable components, sport
comfortable user interfaces, have fenders and a bit of cargo capacity,
and don't fail structurally in use.

Of course I should point out that 40 lbs. is one-tenth their usual
payload!

Chalo Colina

In article <[email hidden]>,

Shawn Curry said:

Van Bagnol said:

Did anyone see the latest issue of _Mountain Bike Action_ featuring
Honda's mountain bike and CVT drivetrain? Any comments?
Van

Read it at the library. Looks fat and inefficient (I should know).
Hopeless concept as an XC bike. Chain drive is just too efficient.
Shawn

I think you meant derailleur shifting rather than chain drive. The bike
still sports chain drive, although unlike in the CVT, a derailleur
mechanism gets out of the way once the bike is in gear.

It should be, however, more mechanicallly efficient than the drive
shafts used in all-wheel (both-wheel?) drive bikes. And according to the
article, the Honda CVT's mechanical efficiency was superior to a
multispeed planetary hub (e.g., Sturmey-Archer 3-speed).

Van
--
Van Bagnol / v b a g n o l at earthlink dot net / c r l at bagnol dot com
....enjoys - Theatre / Windsurfing / Skydiving / Mountain Biking
....feels - "Parang lumalakad ako sa loob ng paniginip"
....thinks - "An Error is Not a Mistake ... Unless You Refuse to Correct It"

Van Bagnol said:

Quoted message said:

Read it at the library. Looks fat and inefficient (I should know).
Hopeless concept as an XC bike. Chain drive is just too efficient.
Shawn

Quoted message said:

I think you meant derailleur shifting rather than chain drive. The
bike still sports chain drive, although unlike in the CVT, a
derailleur mechanism gets out of the way once the bike is in gear.

What is the purpose of the derailleur in that event? A derailleur is
largely responsible to take up chain length changes.

Quoted message said:

It should be, however, more mechanically efficient than the drive
shafts used in all-wheel (both-wheel?) drive bikes. And according to
the article, the Honda CVT's mechanical efficiency was superior to a
multispeed planetary hub (e.g., Sturmey-Archer 3-speed).

What the two wheel drive folks overlook is that if there is
significant drive on the front wheel from a drive shaft, flexible or
otherwise, it will cause a steering torque equivalent to the drive
torque. Fortunately they don't transmit much of anything being merely
slightly thick speedometer cables and slip clutches.

Jobst Brandt
[email hidden]