Why Do We Never See Belt Drive?

[StevieB]

Why, oh, why? Geez, it works on tourquy Big twins, and Buels, why not on other mid-sized sport bike? As I see it...

PLUSES- long life, zero maintenance. Quiet operation. Built-in cush drive, I would think.

NEGATIVES- harder to change ratios. Can't be shortened, so you would have to buy a new, longer belt if you did want to change ratio. May not be available in one or two cog bigger size.

Overall, I would go for it.

[loudnlow7484]

From Japanese sportbike manufacturers perspective.

Negatives- hard to change gearing, wider (harder to package in frame), no good for racing, the drive belts have been developed, and made in USA primarily, don't sell as many replacements b/c of longer life

Positives- ............. can't really come up with any.

[bedabug0]

+1 if it aint broke dont fix it

[Black_peter]

Kawasaki looked into it..
Belts are also bulkier.
In order to get a belt drive on a GSXR1000
it would be really wide and thick..
Wide thick belts rob power.
(wide thick belts are not flexable)
Take up space.
Require wider heavier pullys.

Belt drive is like Front Wheel drive..
As my brother in law put is so well:
"If #$%$#$ front wheel drive were so %$#$^
great you'd see it on the banks of #$# Daytona International Speedway!!.."
(actuall he had a few more *&#$ in there..)

[crazymofo]

your brother in law puts it exactly how i would BP LOL!!

belt drives cant handle abuse and extreme horsepowers without the need for expensive belts with inbuilt reinforcement, chains handle shock loading a lot better then the belts,

theres not many sportbike riders out there that will leave it in 6th gear all day long, they constantly row the box, dropping back, sudden engagement of the clutch etc.. belts cant handle this, where as chains can.

belts are found usually on the low revving, cruiser bikes because of where they are commonly ridden.. freeways at constant or moderately applied throttle with minimal gearchanges (relying on engine torque)

put it this way... if belts could handle abuse, why would BUELL (a belt driver user) revert back to a chain drive with their xbxx(is that the right model name??!) race bikes they introduced into foruma xtreme??


cheers.joe.

[The CyberPoet]

Re: Why Do We Never See Belt Drive?

There is a limit on the RPM around a sprocket a belt drive can handle reliably at any given load stress (this is why you normally see very large sprockets for belt-drive bikes), and the total HP it's capable of handling (belt-drive bikes may have high torque, but have low HP numbers). Although jumping belt teeth doesn't sound like a big deal (the belt will even out again), the shock to the components of the transmission when it happens can be very damaging (unload/load in very fast sucession) and the result at high RPM's can snap a belt in a heartbeat as the power slaps the belt again.

Chains can be given virtually all the benefits of a belt with the right engineering (based on your list):
Long Life - an well maintained sealed-ring chain will already outlast the lifespan of a belt under any identical set of power/speed requirements.
Zero maintenance - with an automated chain oiler and the right oil, a chain becomes a virtually zero maintenance item on a bike (the right oil will carry away dirt as it flings off again, and the use of perfect oiling will minimize any stretching of the O-rings by acting as an additional damping surface, reducing o-ring failure that leads to elongation, chain slack and noise).
Quiet operation - chains are only noisy when they aren't lubed right or adjusted correctly for length (see chain oiler above again). A well maintained chain is never noiser than the other systems on the bike, even with the OEM exhaust.
Drive cushioning - modern O-ring chains do have cushioning, in several places -- including in the sealed lube under the roller surface, in the O-ring, in the oil between the roller surface and the sprocket. The cush pads are a final addition and mostly deal with slack-to-no-slack transitions (most belt-drive bikes have some form of cush pad as well).

BMW uses a belt drive on one version of their F650's (F650CS), but you're looking at a 50 HP / 44 lb-ft torque bike designed specifically for the city dweller (Urban Attack Bike) where convenience in zero-maint is part of the selling point of this very unique bike (as well as a combo audio system & hard-case tankbag that snaps into a recess in the top of what appears to be the tank but isn't).

Maybe the real question you should be asking (and one I'd like the answer to) is why there aren't more hollow carbon-fiber+kevlar based shaft drives commonly in production. The weight penalty becomes minimal with a hollow multi-laminate tube and the benefits are significant (the only big drawback is inability to readily change the gear ratios).

Cheers,
=-= The CyberPoet

[Black_peter]

Re: Why Do We Never See Belt Drive?

Maybe the real question you should be asking (and one I'd like the answer to) is why there aren't more hollow carbon-fiber+kevlar based shaft drives commonly in production. The weight penalty becomes minimal with a hollow multi-laminate tube and the benefits are significant (the only big drawback is inability to readily change the gear ratios).

Cheers,
=-= The CyberPoet

Cause everyone knows shaft dive is for sissys and BMWs!!

I had a CB650 with a shaft.. and I have to say it was nice.
I tried to get it to mis-behave the way the motorcycle mags
said it would but never could. Same deal though,
MV Augusta ran shaft on the street but never on the track..
Same wuth Guzzi..

[StevieB]

If this were a Busa and/or racing forum, I would be more accepting of some of the critisims, but Kats are not busas or race bikes. I still think belts would be a better choice than chains on most bikes up to about 750 cc's.

I did appreciate loudandlow's jap maker perspective. Not that they have any real good excuses...

Carbon-fiber shaft drive? Can you say "expensive?"

[Black_peter]

OK let me put it another way:
If it were cheaper, lasted longer, worked better then the
Japanese bikes would have them.
The benifits would look good in the ads.
Most likely they would make more money
in replacements as few buy OEM chains but you might have to
buy an OEM belt. Think of it like FI..
Once the equipment and software got cheap and reliable
bikes have been switching over. I'm betting that like cars
Carbs on bike will be a thing of the past. Meanwhile belts
(first used on production bikes in the 70's) may never get there.

[The CyberPoet]

Actually, I had another thought on this matter (that may or may not have any basis in belt/non-belt use), that occurred to my sleep-addled brain:

Denonations per second and elastic recovery time for the material.

Belts are commonly used on single and VTwin engines that have relatively low redlines.

A VTwin turning at 4500 RPM is churning out 75 power-pulses per second (one per revolution).
A Single turning just shy of 8k is churning out 66 power-pulses per second (one every other revolution).
By comparison, a four cylinder around 8k is churning 266 power-pulses per second (2 per revolution).

The great increase in the number of power-pulses may induce a problem with belt stretch and materials break-down in the belt itself.

hmmmm...

Cheers,
=-= The CyberPoet

[loudnlow7484]

Actually, I had another thought on this matter (that may or may not have any basis in belt/non-belt use), that occurred to my sleep-addled brain:

Denonations per second and elastic recovery time for the material.

Belts are commonly used on single and VTwin engines that have relatively low redlines.

A VTwin turning at 4500 RPM is churning out 75 power-pulses per second (one per revolution).
A Single turning just shy of 8k is churning out 66 power-pulses per second (one every other revolution).
By comparison, a four cylinder around 8k is churning 266 power-pulses per second (2 per revolution).

The great increase in the number of power-pulses may induce a problem with belt stretch and materials break-down in the belt itself.

hmmmm...

Cheers,
=-= The CyberPoet

hmm, good thought! That mere .00376 second may not be enough time for the belt to spring back. Then it gets stretched again, and again, and again, without being able to recover between pulses.

I do agree, also, that if it were a better thing, that it would be on bikes now.

[StevieB]

Belt Drive and Race Cars

Black_Peter wrote: "Belt drive is like Front Wheel drive..
As my brother in law put is so well:
"If #$%$#$ front wheel drive were so %$#$^
great you'd see it on the banks of #$# Daytona International Speedway!!.."

What a lame argument your brother-in-law presents. 1) not all performance questions are answered on the racetrack, 2) there are many other races besides Daytona, 3) several race cars ARE front wheel drive. I once watched, in great amusement, a Mini Cooper (original, smaller one) dice it up with a big-block Corvette on a road course. The 'Vette would blow past the Mini on the straight, every lap, but the Mini had no trouble getting past the 'Vette in the curves. The Mini won his class, the Vette, did not.

And besides, real race cars turn left AND right. And don't EVEN give me half a chance to tell you my favorite NASCAR dirty joke...

[Black_peter]

Re: Belt Drive and Race Cars

Black_Peter wrote: "Belt drive is like Front Wheel drive..
As my brother in law put is so well:
"If #$%$#$ front wheel drive were so %$#$^
great you'd see it on the banks of #$# Daytona International Speedway!!.."

What a lame argument your brother-in-law presents.
1) not all performance questions are answered on the racetrack,

Such as? Parking? fuel economy? Emissions...
Now what is lame? OK my B-I-L is a circle track fan..
Name front wheel drive car that has raced in GP?
Bottom line it that when price is not an option,
think Porsche, Lambo etc they are RWD cars.
Corvettes, Mustangs too..

2) there are many other races besides Daytona,

See above

3) several race cars ARE front wheel drive. I once watched, in great amusement, a Mini Cooper (original, smaller one) dice it up with a big-block Corvette on a road course. The 'Vette would blow past the Mini on the straight, every lap, but the Mini had no trouble getting past the 'Vette in the curves. The Mini won his class, the Vette, did not.

OK sure... The Mini won it's class.. and the top classes are RWD.
Why?
Any serious "race" car, pro or SCCA is either RWD or AWD..
Even when the IROC race was Dodge Daytonas and not Camaros
the Daytonas were not the FWD steet versions but RWDs...

My point was that if belts were better why aren't they on MotoGP
bikes? After all preventing mechanical breakdown is paramount in racing.
Also they could have a pit full of belts and pullys to make fast gearing changes. Belts are for Harleys.. Just like trix are for kids..

Seems to me you are getting a little worked up over this.
Why not just convert your bike to belt drive and prove us all stupid?

[The CyberPoet]

Re: Belt Drive and Race Cars

Name front wheel drive car that has raced in GP?

There have been a bunch of 4WD formula 1 cars, especially in the 1960 thru 1970 time frame... does that count?
OK, I'll name one front-wheel drive GP car: the Miller 91, a super-charged straight-8 (1926).


The reality is that the standards organizations for many of these racing classes come to require some specific configuration over time because a variation on an unregulated theme provided too much advantage to somebody. Front wheel drive presents a serious issue with corner clearances in tight racing, because front engined-front wheel drive cars can swing the rear wide easily (esp. on power-off conditions during cornering), the primary reason it is not permitted under F1 and most GP class rules (to likely to induce damages to others in the turns).

But, Black_peter has it right -- front wheel drive is not inherently conducive to high speed racing in general, because of stability factors (rear-wd cars have neutral stability in emergency situations). Classes in which front wheel drive cars are raced have racers who have learned to compensate for this fact... and sanctioning bodies which have not eliminated the use of front wheel drive.

Other Thoughts/oddities:
There was also a famous GP car with four front wheels on two separate (parallel) axles. And this year, Audi won the 12 hours of Sebring running a new Audi R10 V12 TDi, the first diesel to win a endurance race in the modern era.
Want weird? Check out the history of the Rokon, the first all-wheel drive commercial motorcycle (complete with hollow aluminum wheels that hold 4.5 gallons for fuel, and when emptied, will let the motorcycle float on it's tires over water).


Cheers,
=-= The CyberPoet

[Black_peter]

Re: Belt Drive and Race Cars

Name front wheel drive car that has raced in GP?

There have been a bunch of 4WD formula 1 cars, especially in the 1960 thru 1970 time frame...does that count?

Any serious "race" car, pro or SCCA is either RWD or AWD..

So sure it counts but I said that...
You just wanted to show off the "family photos" didn't you??
If I'm not mistaken there was a diesel Indy Car once.. no?