Aug 27, 2012

Shaft, Chain, or Belt?

Because one of MMM's contributors recently suffered a catastrophic chain failure on her Versys, a bunch of us got into a conversation about shaft drive vs. chain drive vs. belt drive. My editor, Sev Pearman, is radically in favor of shaft drives over practically everything, especially chains. One of the technical contributors and a recently successful racer, Dave Soderholm, argued for belt drives. I'm old, not easily convinced by emotional arguments, and stuck with the experience of my lifetime, so I'm mostly on the side of chains and have no particular objection (other than cost) to shaft drives and seriously doubt the reliability of belts because Harley uses them and they are only found on cruisers and other toys (like electric bikes).

Here is some of the text from that discussion:

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From: Cat on a Kawasaki 
Sent: Sunday, August 19, 2012 6:38 PM 
 Subject: Why my next bike will be shaft driven 

 Sunday ride, nice weather, going to get my nails done then off to a barbecue. Wait, what the hell...? (I watch in my mirror as my chain spins away on the road behind me) This is on 35W southbound, south of the Lake exit and north of the US-10 W exit. ONE vehicle stopped -- ONE!!!? -- a Goldwing rider and his wife. I'm glad they stopped. And I'm /very/ disappointed with the rest of the motorcycling community.

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From:  T.W. Day 

Was it a replacement chain, a new/old chain, or a clip/riveted master link? I've been on bikes since the 60's and I've never had a catastrophic chain or sprocket failure. Obviously, they happen, but drive shafts fail too.  I had a CX500's bevel gear toss a tooth on a trip to SoCal in the 80's. I lucked out and it happened (or jammed) at low speed. I was able to pull the final drive apart, pick out the pieces, and limp back home where I rebuilt the thing. I've had infinitely worse luck (1/0) with drive shaft bikes than chains, when it comes to catastrophic failure. 

Thomas Day 
Minnesota Motorcycle Monthly Magazine 
http://http://mnmotorcycle.com/ 
http://geezerwithagrudge.blogspot.com/ 
thomas@motorbyte.com
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From: Cat on a Kawasaki 

It was a master link on a replacement chain that had about 8000 miles on it. The chain chopped a chunk of aluminum out of the protector-thingie (I have no idea what that part is called), but there weren't any cracks or other damage. Whew! I still don't know why the clip came off. I found the master link in the chain lube goo - it was bent as if it had taken some pretty good pulling stress before it finally gave out.  

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From: "T.W. Day" 

Thanks for the update. That's an interesting failure mechanism. In at least a couple hundred-thousand motorcycle miles, on and off-road, I've never had that happen. I'd be suspicious that the master link clip had been installed improperly, had been reused, or that the master link plate had not been compressed all the way, allowing the clip to sit on the edge of the pin grooves rather than firmly in the grooves. There is a good reason for using riveted master links, but I've never been afraid of the field-repairable style links and haven't had a failure in 40 years of riding. 

I have had three drive shaft bikes; a 1979 CX500 Honda Deluxe and a pair of XTZ550 Yamaha Visions. They were all reliable performers, if a little overweight. There is maintenance to be done to the rear drive and most riders blow it off, sometimes resulting in short drive life. The rear drive oil should be evaluated every time you replace the rear tire and that is a messy, time-consuming process. Some folks recommend changing that oil every time you replace the engine oil. Usually the splines at the end of the drive need to be greased at the same intervals. I know guys who have never changed that oil and lucked into long mileage and I know guys who blew off the maintenance and ended up with $2,000 in driveline repair costs for their lack of effort. I know at least one guy who did all of the maintenance required and still had a rear drive fail at 20k miles. "Maintenance-free" is a marketing delusion, especially if you go anywhere interesting on your motorcycle. 

Rocks are a drive belt killer. A moderately hard fall can bust drive shaft cases. A long ride in a hard rain can completely de-lube a chain and set it up for early failure. You buys your toys and you takes your chances. 

If you've read my stuff, you know I am unaware of this "motorcycle community" of which you speak. Motorcyclists are just people with no more connection to any overall community than the typical American voter. Waving aside (the motorcyclists' equivelant of saying "I'll pray for you" or "I'll hope for the best, assuming I don't have to put out any effort to help you"), I've had as much luck with old and young guys in pickups stopping to offer assistance as I have motorcyclists. For some reason, guys in driving pickups and wearing cowboy hats have been more valuable to me than anyone in or out of a helmet. 

 Mark Lawrence, by the way, is one of my favorite maintenance resources for practically all things motorcycle. His take on drive shave maintenance is worth reading. Mark was way ahead of the curve on the V-Strom 650 and his advice has kept my bike going strong through some tough times and places.

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 From: Soderholm, David 

 Belts are the way to go - strong / light / quiet / clean / lash free / minimal input into suspension..........perfect drive for a street bike. 

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From: T.W. Day 

 I've never had or ridden a belt drive bike. I've always questioned the strength and durability of belts. Of course, nothing I've ever owned has been a committed "street bike." Sooner or later, we're going riding on dirt roads and I suspect that could be a weak "link" for belts. Since a belt is, by design, a continuous loop, doesn't that mean considerable disassembly for replacement? 

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From: Soderholm, David 

That's a good point Thomas, but most belt drives have a very long to life time interval period on replacement. They are also tested for rock and gravel off road during development. They are very tough.......
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From: Sev Pearman

The shaft drive thread 
Pfft Anecdotal evidence 
And all 1800 Goldwings are shaking death traps. I know, cuz the innernets tell me. 

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From: "T.W. Day" 

If "anecdotal evidence" is all we have, it's infinitely more valuable than myth and wishful thinking. The only discouraging word I have about the Tenere is the 42mpg bit. A shaft, one way or the other, is barely a consideration for me. I liked that bike and liked my XTZ550 Visions. If the Tenere came in a 65mpg 550 and at least $4k cheaper, I'd be on it. My point is that shaft drive is a wash, in the long run. And I've had a few of these bikes for long runs. I've never had a single sided shafter, though. That might have some serious advantages, maintenance-wise. The Honda Hawk is one of my favorite machines, concept-wise. I don't know anyone who put big miles on one, though. I know people who have them, I'm just not impressed with 15k miles of use


Does the fact that BMW put a chain on their F800GSe do more than provide "anecdotal evidence?" (I know, the picture was on the internet.) At one of the first Cycle World bike shows I attended in Minnesota, BMW displayed one of their their non-factory Paris Dakar boxers, which was chain drive. I have always wished I'd taken a good picture of that bike. I never seem to have a camera out or an audio recorder running when it really matters. Clearly, I do not belong in the news business. 

Let's face it, it doesn't much matter to people in my socio-economic bracket. There isn't an interesting shaft drive available in my low-ball price range. There is no chance I'm going to own a five-digit motorcycle, ever. There is little chance I'd ever want a drive-shaft cruiser, which might be in my price range but I'm not that old, yet. (I don't plan to live that long, either.) So, if there is a small reliability/price advantage, the initial cost overwhelms the conversation. If that were all there were to it, I'm sure all factory on and off-road race bikes would be belt or shafties. Since they are overwhelmingly chain driven, there is clearly more to it.



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From: Sev Pearman

I don't think that is accurate. Permit me to add this observation

Cruisers and tourers may run belts (a/o shafts) due to fixed FD ratios.  No one cares to adjust it do the FD ratio is fixed. Having said that, BMW & M-G offer a variety of REAR pinion ratios to alter overall ratio

Sport bikes and offroad machines have stayed w chain because it is easy to adjust when gear ratios are changed

If not, a rider would have to stock x different length belts for as many possible FD gear ratios

This is a question of final drive ratio adjustment, not reliability


 I pity the poor salesman who has to sell you any machine 
:•D 

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From: T.W. Day

I always buy used from owners, never dealers, at the lowest price I can beat out of the seller, and rarely want anything badly enough to worry about the deal if it falls through. No salesman wastes much time on me because it is, apparently, obvious the moment I walk through the doors than I'm just looking. I bought my first and last new bikes in 1974 and only new car of my life in 1973. "Fool me once, shame on you. Fool me twice, shame on me." I rarely go back for a whipping twice, unless getting my ass kicked at the race track counts. 

Do you have evidence that chains are standard because of the adjustibility or is that opinion?  

I doubt that a lot of gear ratio modifications take place in the Dakar or in enduros and cross country races, Isle of Man, and the rest of the endurance racing world and I suspect that if reliability was a serious issue with chain drives, even road race tuners would find a reasonable way to adjust gear ratios; as you've mentioned BMW and MG do already. I don't think the drive issue is as clear and simple as you appear to believe. I think the racetrack is equivalent to tens of thousands of miles of "normal" use, so if drive shaft systems possessed reasonable power-to-weight and efficiency performance and provided a reliability advantage, we'd be seeing them on the track. 

The fact that belts are practically non-existent outside of the low-performance, maintenance-ignorant cruiser market says a lot to me. I have no objection to drive shaft power transfer, but I'm unconvinced they are the bulletproof, no-maintenance, cost-effective drive line you're hoping they are. 

I'm also unconvinced that encouraging already-barely-conscious riders to buy "let's pretend these are no maintenance" bikes is a good idea. Going over the chain is just a small part of what ought to be good, regular maintenance. It's not difficult to make daily maintenance a reasonably clean activity. It does force us to look at axle bolts and adjustments, and to scan other parts of the bike. It gets us closer to the "Zen" of motorcycle maintenance and that's always a good thing. 

Now, when you get back from 2,500 mile (2,000 off-pavement) North Dakota ghost town tour and can still say, "Time on Victory bikes has made me a believer in belts as well," I'll reconsider. Until then, I'll see your "pfft" (although I'm not sure what means and raise you a couple of "humphs." A few piddling miles around town doesn't convert me to abandoning a system that has only improved dramatically in my lifetime. 

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Some of you folks are more experienced, technically more capable, and bigger thinkers than me. What are your thoughts, opinions, and what facts can you bring to this debate table? 

11 comments:

  1. I've never owned a belt drive bike, but I've seen more than 1 rock get pushed into and poking through the belts from riding on gravel. Some brands have more guards around the belt than others.
    I ride with a guy that owns a belt drive cruiser. His bike will squeak terribly after riding on gravel. The squeaking goes away after washing the grit/dust off the belt and pulleys.

    Some brands of motorcycles have shaft drives that are prone to self destruction.

    I currently own 3 bikes, 2 chain 1 shaft. One of the bikes, a ZX14 is on it's second chain I replaced it and the sprockets at 30,000 miles. A heavy rain and a "too tight" adjustment on my part made it die early. It would make odd cracking sounds.
    A new set has cured that. I was a little leery of riveting my own chain, but 10,000 miles later, I'm not so worried.

    My other chain bike, a WR250X, doesn't have enough miles on it to worry about wear yet.

    The shaft drive bike, an FJR, has not been totally maintenance free. I change the gear oil every other engine oil change. I pulled the drive unit off and lubed the nearly dry spline shaft shortly after I bought it. It came nearly dry from the factory!

    No one should believe any final drive system, belt, chain or shaft is maintenance free.

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  2. Thanks for the backup, Eric. Regardless of how it came off, I'm not disrespecting any final drive system (except some aspects of belt systems), but I'm unconvinced that a "no maintenance" motorcycle is a good thing, even it were true. Drive shaft systems clearly aren't in your experience or mine.

    I suspect the previous owner killed the first chain on my WR and I replaced it at about 3,000 miles before looping Lake Superior last year. The chain slider was also wreaked. So far, 2,000 miles later, the new chain looks great and the slider is also in fine shape.

    I usually get about 12-15,000 miles from chain and sprockets on the V-Strom, but that includes a few thousand miles off-pavement. I have never ridden a shafty off-pavement and have no idea how they would hold up.

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  3. Back when Butler & Smith, formerly the BMW motorcycle importers, had a race team briefly in the US, they carried numerous already-set-up rear gearsets whose contact patterns had been carefully adjusted. When they needed a ratio change (as racing does) they switched out the whole thing. And of course the gears are quite heavy.

    But for someone working on another New-York-to-Patagonia-by-motorcycle article, shaft drive would seem to have advantages. Or any kind of utility riding.

    Yes, I suspect the Har-Davs have those fanbelts because (a) they have modest hp and (b) suspension movement is kept to a bare minimum by the low seat height. Ducati got to where they were changing the fanbelts on their cam drives every day in World Supers, so now they've switched to metal chains in the new Panigale 1200 twin.

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  4. Also cam belts are on constant center distance, which rear wheel drive never is!

    Naturally marketing has to present everything as no-maintenance (like US democracy).

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  5. If the argument is "I hate maintenance" and that's the only criteria for picking a bike, Sev is probably the winner with drive shafts. I'm unconvinced that the price, weight, complexity, fragility, and loss of balance is worth that advantage. Of course, I'm not in the market for a $14k, 600 pound, liter-or-larger motorcycle. Never have been, never will be. I have a hard time justifying my 650 V-Strom for most of my motorcycling.

    I think the argument for belts is a lot shakier. They only tolerate moderate power and very little material interference without failure. Someday, maybe. We're still waiting for a powerful, modern motorcycle that takes a chance on belt drives. Victory and Hardly don't count as either powerful or modern.

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  6. I don't have definitive answers, but like you I've listened to or read a lot of arguments. Here's what I've taken away:

    1) If any of the three types was universally superior, it would have beat out the others except for niche markets. None of them has, so clearly none of them is universally better.

    2) Which one is better in any application depends on the application. Belts are good if you only ride on the street and want "I'm going to take it to the shop for a tune up every N-thousand miles" maintenance, and don't mind N being fairly small. Drive shafts are good if you have the same view, but want a larger N and ride in the rain. Chains are good if you're not sure what conditions you'll be driving in, and want to be able to make repairs easily on your own.

    3) In any case where there are multiple options under discussion, there will be someone for each option who argues that that option is always best. Those people will, almost universally, be wrong. (There are, of course, exceptions. Sometimes one option really IS clearly the best. But usually....)

    That said, I like chain drives because they appear to be more reliable than belts (I have yet to see a slipping chain!) and easier to inspect than shafts.

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  7. Andy,

    I do not disagree with anything you've said. Chains are definitely stronger than belts and more durable. Because I have never seen a dirt road I couldn't love, "more durable" is a big deal with me.

    There are lots of things to like about drive shaft systems, maintenance in the field and cost are not among them. Weight is an issue, too, for both belts and drive shaft systems. Unless the torque is minimal, the pulley size becomes a big issue and there goes any weight advantage the belt might offer.

    My WR250X is my most recent experience with a slipping chain. The previous owner had done a poor job of maintaining the chain and as the failing chain stretched it slipped under hard, low-gear throttle applications. Adjusting the chain helped for a bit, but not for more than 500 miles. We're talking a seriously long-travel rear suspension there, something a belt wouldn't cope with at all.

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  8. I've had all three systems. Tend not to like the shaft drives. Heavy and complex, still needs maintenance, and could be pricey to fix.

    Have a belt on my BMW F800S, an 85 HP, mid 400 pound street biike. I live down a long gravel driveway, but no issues with stones. It is well shielded. I like it, but with one major exception. It only lasted 24,000 miles, and it costs $450. No aftermarket substitute.

    Have a chain on Ninja 250. No issues, but a bit messy. And yes, I did change the gearing on the Ninja for my highway commute, which made me appreciate the chain and sprocket arrangement.

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  9. Now that is news to me and one of the questions I was asking. I didn't know the F800S was belt drive and I wouldn't have guessed the belt could be that expensive.

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  10. Hi Thomas,

    You say you like the Honda Hawk. On this side of the pond they came in two capacities, 600 & 650cc. I ran an NTV600 some years ago for 94,000 miles. It was without doubt the most reliable bike I have ever owned, but it was physically small, and thus uncomfortable on high mileage days. I got into shaft drives while working as a motorcycle courier in the bad old days when "the troubles" were still part of everyday life here in Northern Ireland. Finding a way through Belfast when the bombs were going off was an interesting experience!

    The only problem with the NTV's shaft was the pathetic plastic cover over the wheel retaining nut. It let dirt through and once in there was very difficult to clean out without pushing it further into the oil seal that protected the bevel. I rebuilt the bevel once after that seal failed and from then on used silicone sealant on the plastic cover. There were no more problems.

    Ian

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  11. Ian,

    It's a "like" with minimal experience, unlike you. Now that you describe your experience, I can imagine I might think the Hawk is "too small" for my age-disabled lowered flexibility. Knees, especially. A friend had a Hawk NT650 back in the 90's and I loved riding his bike. He did absolutely no maintenance, so I had no opportunity to work on the bike with him.

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Disagree? Bring it on. Have more to add? Feel free to set me straight.(Spammers get serious. Spam goes straight to trash and is never read.)