Author Topic: belt drive  (Read 9044 times)

riptoff

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belt drive
« on: March 14, 2010, 05:38:20 AM »
I saw a bike (Trek) in a shop today with belt drive. The reviews are good, but how about the pedalling efficency?
Presumably the belt is less efficient than a chain, but has this been measured?
 

Danneaux

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Re: belt drive
« Reply #1 on: January 05, 2013, 07:46:22 PM »
Sorry for the (very) late reply. Yes, the difference in efficiency between chain and belt drive has, indeed, been measured, thanks to Jason Smith's FrictionFacts website.

According to test results there, a belt drive is considerably less efficient than an equivalent chain drive, exhibiting a staggering 35% more friction compared to a traditional single-speed chain drive (as used on bikes with Rohloff and other IGH drivetrains).

The report is free from Friction Facts, but in congruence with their honor system of not passing on reports (even free ones; it really is worth a visit to the site to see the quality of their downloadable reports), I'll just post links to Bike Radar's brief summary of the results here: http://www.bikeradar.com/road/news/article/chain-or-belt-drive-which-is-faster-36074/

With more followup here on general drivetrain/chain friction:
http://www.bikeradar.com/news/article/friction-facts-measuring-drivetrain-efficiency-35694/

Basically, the results shake out like this:

At low to normal loads, the chain is more efficient than the belt 'cos Gates recommends a considerable amount of pre-tension on the belt to keep it in place so the lugs won't slip. This high pretension increases belt friction losses.

At high loads, the chain's friction increases and the belt becomes relatively more efficient in comparison, eventually passing the chain for efficiency.

Untensioned, the chain shows very little frictional loss. Similarly, without Gates' recommended preload, the belt also becomes much more efficient, but at the cost of retention. Using this information as a springboard, Bike Radar pondered...
Quote
...if one were to theoretically supplement a zero-tension Gates system with a lower roller to prevent skipping on the cog, it's then possible that track racers could benefit from a toothed belt drive system.

Additional details – and the full test report – are available via free download at Friction-Facts.com The direct link for the free report is here: http://www.friction-facts.com/test-results/free-reports/free-carbon-vs-traditional-drive

Do be aware one must register to download the free reports from Friction Facts, but I have had no problem with spam afterwards, and the reports are indeed free, as shown on the download checkout page. No payment information need be registered to get them.

Best,

Dan.
« Last Edit: January 05, 2013, 08:14:36 PM by Danneaux »

energyman

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Re: belt drive
« Reply #2 on: January 06, 2013, 04:31:09 PM »
I've been riding a belter now for 4 months or so and to be honest I can't tell any difference other than it seems quieter and I don't get oily trousers.
I read the Bike Radar piece with interest and will agree that only the pro cyclist would possibly notice the 1 watt difference.
Anyway it's an excellent conversation piece !

ZeroBike

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Re: belt drive
« Reply #3 on: January 06, 2013, 05:32:25 PM »
Whats the advantage of using a belt drive over a chain and full chain guard?

Supposedly a full chain guard means that you dont need to clean the chain very often.

Also replacement chains are far easier to source then replacement belts.






Danneaux

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Re: belt drive
« Reply #4 on: January 06, 2013, 05:38:09 PM »
E-Man!

I was hoping I'd hear from some "belters" among us!
Quote
...to be honest I can't tell any difference other than it seems quieter and I don't get oily trousers.
I'm wondering if --as with so many things on bicycles -- perception is more key than practice in either aiding us or holding us back. Cycling is, after all, a sensory and tactile experience, and it may be similar to how a good waiter can shape a patron's perception of a meal. Opening the tureen at close range to the diner, tipping the cover back to waft the steam and flavor-enhancing odor as the waiter backs away is a huge part of creating a favorable "response set" toward the meal.

Me? I'm a bug for having a quiet bike and will go to great lengths to make and keep it so. To me, a quiet bike "feels" faster.

It isn't to different from narrow tires pumped up hard with air. The increased high-frequency vibration in the ride makes the bike "feel" faster...even if it is not.

A visit to local builder Co-Motion shows they are into belts in a big way...especially as replacements for timing belts on tandems.

Even if there is an actual loss in efficiency, I'm thinking the quiet drivetrain and reduced vibration (not to mention clean pants) offset that in terms of providing a Pleasurable Riding Experience™.

I think it doesn't much matter in practice so long as you enjoy what you're riding and -- as a result -- you either ride more or are more apt to ride. A happy, satisfied rider will generally ride more. It's all good in that respect!

I intend to try for many of the belt drive's advantages as soon as Hebie make a Chainglider compatible with a 36t chainring. Quiet (hopefully!), low-maintenance, and clean trousers are all possible benefits.

Best,

Dan.
« Last Edit: January 06, 2013, 07:14:37 PM by Danneaux »

energyman

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Re: belt drive
« Reply #5 on: January 06, 2013, 09:47:34 PM »
Whats the advantage of using a belt drive over a chain and full chain guard?

Supposedly a full chain guard means that you don't need to clean the chain very often.

Also replacement chains are far easier to source then replacement belts.







Advantages are : life span, conversation piece, clean trousers (pants to you Dan !) Weight and finally all the reasons that the automotive industry quote when a new engine has belts fitted instead of chains.........
Replacement belts ? - Well if it lasts as long as Gates quote and the world is kind to me I guess it will out last me and then the bike will be given to one of my sons.
In another 50 years we will no doubt be riding penny farthings as "the latest innovation" from the bicycle industry.  :D

pdamm

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Re: belt drive
« Reply #6 on: January 07, 2013, 03:26:37 AM »
I don’t have a belt drive but my better half does and I maintain her bike.  She has done 7,000km on it now after 18 months of ownership.  I have noticed an increase in drag when I rotate the pedals backwards by hand or rather delicately with my fingers.  And the effect is temperature dependent.  Over about 20C (68 F) I cannot tell any difference between reversing the pedals on her bike and my chain driven Raven Tour (both with Rohloffs).  At 10 C (50 F) I can tell the difference when I rotate the pedals backwards by hand (but not with my feet).  In that case her bike seemed to have about the same amount of drag as a friend’s Rholoff equipped chain driven mountain bike that has a chain tensioner on it.

When I was setting up the bike I played around a bit with the belt tension.  I noticed a significant increase in drag reversing the pedals by hand when I had the tension set on the maximum recommendation compared to the minimum recommended tension.  I finally settled on a little bit below the minimum recommended tension for this reason.  I have tried to get the belt to jump the sprocket during test rides but failed.  The bike has a little snub wheel that is supposed to prevent this skipping.  It is located 1mm away from the belt just where the belt sits flush with the sprocket on the underneath of the sprocket.

Our experience has been that it does stay clean and quiet and so far has required no maintenance.  Gates says the belt will not stretch and so once setup you don’t need to periodically adjust the EBB to keep the tension correct.  So far that has been our experience.

Peter
 

ZeroBike

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Re: belt drive
« Reply #7 on: January 17, 2013, 07:53:46 PM »

I intend to try for many of the belt drive's advantages as soon as Hebie make a Chainglider compatible with a 36t chainring. Quiet (hopefully!), low-maintenance, and clean trousers are all possible benefits.


Out of interest, why do you need the chainglider?

Isnt the advantage of the belt drive that you dont need to keep it as clean as a chain?

Danneaux

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Re: belt drive
« Reply #8 on: January 17, 2013, 08:04:11 PM »
Zero!

Good question: On reading over what I wrote, I realize I wasn't very clear; apologies.

What I meant to say was...

"I hope covering my chain with a Chainglider will provide me with a belt drive's advantages: Hopefully, it will be quiet, maintenance will be reduced, and my trousers will stay clean."

You're absolutely correct; if I had a belt drive, a Chainglider would not fit or be necessary.

Hebie tell me a 38T Chainglider front half is appropriate for my 36T chainring. I'll be placing my order as soon as I can determine positively whether I need the commonly-available Standard Length or the less common Extended Length forward section. The Rohloff-specific rear section will fit either front section, and is selected by cog size. My 580M chainstays are pretty long (470mm at the EBB's midpoint, 476.5mm at full-forward rotation), so I want to make sure the model I select will fit properly and not come up short.

All the best,

Dan. (...who always welcomes calls for clarity)
« Last Edit: January 17, 2013, 08:10:57 PM by Danneaux »

ZeroBike

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Re: belt drive
« Reply #9 on: January 17, 2013, 08:18:36 PM »
Are there any frame issues to consider, like are alignment tollerencies the same for both chain and belt systems?

I have also read that because belt systems have to be tensioned with a high force (10 Newtons was quoted) that it causes wear on the bearings etc. 

Id provide links but literally its a sentence here or a sentence there, I have heard people saying these things but have never seen a detailed study or even pictures of such wear.




ZeroBike

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Re: belt drive
« Reply #10 on: January 17, 2013, 09:27:26 PM »
I just emailed a company inquiring about the possibility of getting a belt drive fitted to a nomad.

I think by doing so you are going to void both the warranty on the frame and the rohloff hub.

OK thorn might be a bit more relaxed about the frame warranty but rohloff apparently have to aprove your frame in order to get the hub converted, so by doing it without both Thorns and Rohloffs consent yu may invalidate that lovely "well send you a replacement wheel anywhere in the world warranty".

>Hello,
>
> Im thinking of getting a Thorn nomad MK2 with a rohloff hub.
>
> Could you tell me if its possible to retrofit the coupler you sell to allow the belt to pass through the chain stays.
>
> If so how much would the cost be?
>
> Do you know of any issues I might face, for instance will any frame work well with a belt drive or am I likely to face problems that I dont even know about yet.
>
> Best wishes
>
> Ben


Hi Ben,

the short answer is no we don't do that anymore.

The long answer.......

Basically we're too busy with our own frames to take on work like that anymore. If you do want to go down that route there's a few things to be aware of. The couplers we use now we make ourselves and are available in 16mm and 19mm versions. We can sell those to other framebuilders for fitting. The new ones can be seen on our flickr site
here:

http://www.flickr.com/photos/shandcycles/8371765677/in/photostream

If you're planning to run a beltdrive Rohloff, it's not as simple as it seems. Firstly the belt drive is very fussy about chainline. You need to make sure you can run your front sprocket at exactly 54mm from the centre of the seattube.

Secondly, the rear triangle needs to be stiff enough to keep that chainline correct when you're pedalling, especially under load and high torque situations.

Thirdly you can't just fit a belt sprocket to the Rohloff. The sprocket actually runs on a different carrier. You can send your hub back to Rohloff where they'll fit the appropriate carrier and you can then fit the belt sprocket. Note they'll only do this on frames that have been tested and approved (they don't want people fitting that transmission system to frames not designed for it then getting a bad reputation). I don't know if the Nomad has been approved or not.

Alternatively you could save all that hassle and just buy a Rohloff/Belt compatible bike from us!

http://www.shandcycles.com/frames/allroad-plus/stoater-plus-overview/

We sell a *lot* of beltdrive Rohloff bikes and have a pretty good reputation for what we do. If you can be bothered this customer has a pretty extensive blog and writes a lot about his beltdrive/Rohloff Shand.

http://42bikes.warnock.me.uk/category/a-bike-for-life/page/3/

anyway, sorry for the slight detour there. If you need anymore help/advice don't hesitate to get back in touch and I promise I'll not try the hard sell!

Cheers

Steven

Danneaux

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Re: belt drive
« Reply #11 on: January 17, 2013, 11:32:32 PM »
Zero/Ben!

Very useful information for anyone considering a conversion; thanks for passing it along.

May I share some of my observations and concerns?

Co-Motion Cycles is located here in Eugene, OR, and I was impressed on a recent visit with how their belt-drive version of the Rohloff really requires "systems-engineering" to work successfully -- at a level beyond what is required for a happy and wholesome Rohloff experience. Speaking for myself, I don't think the incremental convenience it offers is worth the extra cost and effort or disadvantages for me. Others may well differ, depending on their priorities and use.

A retrofit can be done -- I have seen one example firsthand*, and it appeared to work flawlessly -- but much depends on the frame used, the effective "gearing" (ratios) chosen, and the skill and engineering expertise of the person doing the modification. Once done, the original frame is nowhere near "original" anymore, and right in a place crucial to its long-term strength and reliability. That would be a prime deterrent for me in going to belt drive, but there's more, as detailed by Andy Blance in his soliloquy published in the brochures. For one thing, it gets one further from standardized parts (even for a Rohloff, which is non-standard compared to the majority of derailleur options), and it makes it more difficult to adjust gearing as you wish (a big stopper for me).

[*split chainstay using a zig-zag cut in a solid insert secured by two 5mm bolts, a custom job. The close tolerances required the seatstay halves be levered apart to pass the belt, and this is where the crimped belt mentioned below met its fate; it really required two persons' hands to do properly. A second, better method I have seen from afar is employed by Dutch maker Avaghon and uses double, overlapped Rohloff OEM sliding dropouts, one welded to the seatstay, the other to the chainstay. The same 6mm bolts that hold the sliding dropout in place also secure the two stays at the drops. A brilliantly simple and secure approach from the looks of it, but requires the sliding dropouts rather than an eccentric].

I do worry about what might happen if even a small twig flipped into the belt-drive. This recently happened to me on a remote logging road with my chain-driven Rohloff Nomad. A pencil-sized twig was flipped up by the front wheel and landed squarely on the lower chain run and was sucked back to the cog-chain intersection. The twig was nipped cleanly in two with no damage, but I kept thinking how this might have cost me a derailleur hanger on one of my other bikes. I'm not so sure a belt would survive such an event unscathed. A rock or a jamming wad of mud might do the same. The belt is effectively rigid at maximum tension, so if something has to give, I think you'd see it in stress on the belt fibers or on the cog-drive "bumps".

Still the concept and technology of belt-drives continue to fascinate me, so I keep current on developments. Thinking aloud, the listed advantages of belts over chains are:
1) Quiet to silent running.
2) No messy oil to foul trousers or legs.
3) No maintenance during its service life.

Well, if I can fit a Chainglider over my Rohloff-equipped Nomad's chain, I'll have matched most of these advantages. A well-lubed chain in a Chainglider is supposed to be quiet, my trousers and legs will be shielded from messy oil stains, and maintenance intervals will be extended but not eliminated. This last is a shortcoming compared to belts, but in exchange, I pick up another advantage: No ingestion of sticks and such as I detailed above ('cos the chain will be fully shielded). Also, I can use standard replaceable and repairable drive components -- chainring, chain, and (proprietary but long-lived) cog/sprocket. A carried spare cog doesn't cost much in weight or bulk and won't be necessary for a very long time (especially if it can be reversed for added service).

Though I take a cut-down toothbrush and ex-mascara brush with me on-tour and floss the chain prior to re-oiling it (and have been known to stop at automobile repair shops and borrow use of their solvent tanks and compressed air), it now strikes me as better to extend the interval between cleanings by keeping the chain cleaner in the first place. I realize a Chainglider might not meet my needs where talc-fine playa finds its way into every nook and cranny, but if it helps on my rides here in the generally cool-and-damp Willamette Valley of home, that will be fine. If I wish, I can always revert to an exposed chain and bash/trouser guard for my desert runs.

I think the reply you received from Shand is a good one, spot-on for all the things that need addressing to have a happier belt-drive experience. You did us all a real service in passing it along so better, more fully-informed decisions can be made. I think Shand did a terrific job answering your questions, and I can only add that with regard to alignment, it remains critical for belt drives; they just do not tolerate the same minor levels of misalignment chains can without resulting in excess wear or outright breakage. Things have to be spot-on for belts, and that includes installation. I saw one break prematurely after it had been twisted to fit through a tight, angled opening in a seatstay. Yes, it was the mechanic's error, but the effect on lifespan was startling. You also asked...
Quote
I have also read that because belt systems have to be tensioned with a high force (10 Newtons was quoted) that it causes wear on the bearings etc.
Like you, I have not *seen* the effects of such wear, but they can be interpolated from the test data comparing chain- to belt-drive friction levels over at Friction Facts, as detailed here: http://www.thorncycles.co.uk/forums/index.php?topic=2433.msg30187#msg30187 Their downloadable report is free after registration.

I love hearing about belt-drives and new approaches, but for now, I'll stay with chains as they're proven for me in my experience for my sort of use. I'm open-minded and a bit cautious all at once. That said, I think belts might prove most viable for use on recreational and commuting bikes rather than for expedition/world touring that included a lot of off-roading.

Please keep us in the loop if/as you pursue this. I'd love to hear how it all goes and what you learn along the way. Thanks for sharing what you have so far!

All the best,

Dan. (...who is not currently in need of a good, stiff belt, but wants to avoid a stiff chain)
« Last Edit: January 18, 2013, 12:10:58 AM by Danneaux »

Andre Jute

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Re: belt drive
« Reply #12 on: January 18, 2013, 12:10:05 AM »
A well-lubed chain in a Chainglider is supposed to be quiet,

Says who?

A Chainglider is silent whether the chain is oiled or not. My Chainglider has about 3500km on it, and even with a well-oiled chain, there was never much evidence of oil inside the Chainglider, just a spot here and there, flung off the chain by centrifugal action. For half that distance I've been running the chain inside the Chainglider without any lubrication additional to the factory lube, and with the factory lube wiped off the outside of the chain. There's no noise in either mode.

I think this is conclusive evidence that a Chainglider's silence doesn't depend on oil or any quality not built into the rubbery plastic from which it is made.

Andre Jute

ZeroBike

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Re: belt drive
« Reply #13 on: January 18, 2013, 12:54:07 AM »
Thanks Dan.

I think I came to the exact same conclusion as you but via a slightly different means, namely the availability of parts.

I figured that for most situations a chainglider would serve almost as well as a belt drive but the chain and had the advantage of being available all over the world whereas the belt is something thats difficult to replace on tour.  Also its only produced by one company, Gates, and therefore could be taken out of production at any time.

Its funny that you mentioned comotion as only the other day I was discussing the firm with a fiend.  I said that from my point of view coomotion dont really make decent expedition bikes.  My feeling is that the quality of comotion is amazing but the design philosophy is somewhat muddled.  I think that coomotions design philosophy is to bring all of the best and latest parts together on one bike and than to assume that as each part is the best available then the end result is the best possible bike.

If you look at the Rohloff Americano the problem starts with the choice of disc brakes, which personally I dont feel are suited to an expedition bike as they are more difficult than rim brakes to maintain on extended tours where tools are minimal and work is done in the middle of a field as the sun is going down.  Personally I feel rim brakes are a better choice for the tourer as parts are readily available worldwide and so far I have never been in a situation where I felt that i needed more stopping power.

Then they choose to use tandum hubs to overcome the problem of dished wheels that the discs have just caused again availability issues have been created where they didnt need to be.

Then they choose 29" wheels which I dont think would make that much difference in terms of ride quality on a loaded tourer (although Im sure you would notice unloaded) but this wheel size makes it harder to source tyres and rims in some places in the world and makes the bike harder to pack for transportation on a plane.

Then, as you say, they are pushing the belt drive system which we have already talked about so I wont repeat what we have said.

And finally there is the paint, as far as I can see they only offer a wet paint option where I feel that a powder paint is a better choice as it can be applied thicker which should make it more durable, which is exactly what you want on a bike thats going to travel the world.

Finally I dont think they offer the amazing rohloff waranty that Thorn offer.  Rohloffs cause availability issues and they are expensive so its very reassuring to know if it breaks a new wheel will be sent out to you otherwise IMO the rohloff would have to lose some points as you couldnt really send it back to rohloff and wait for it to be repaired and sent back so you would end up having to buy a new one or end your  tour if it broke.

So whilst the comotions are really well built bikes I really dont think they are suited to the more expedition side of touring.  IMO its a bike thats designed to be used in North America or Europe  and not worldwide.


Danneaux

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Re: belt drive
« Reply #14 on: January 18, 2013, 01:05:03 AM »
Quote
[Dan wrote above]"A well-lubed chain in a Chainglider is supposed to be quiet,"

[And Andre asked, "Says who?"

Hi Andre! This was an issue I have run into repeatedly in my research prior to ordering a Chainglider. It is frequent enough I thought it deserved mention, though at odds with your experience (I'm hoping yours is the rule, rather than the exception). Some examples:
http://cyclea2b.blogspot.com/2010/10/hebie-chainglider-nexus-part-7.html
Quote
If you think about it, one of the benefits of having the chain completely enclosed is that you can have it bathed in copious amounts of oil without worrying about it going all over your trousers. So I put it back together with plenty of oil on the chain and plenty on the inside of the glider's parts. Then rotated the cranks a few times whilst pouring yet more into the oiling port.

It's now running seriously smooth & I wish I'd just done this right from the start.

http://42bikes.warnock.me.uk/2011/03/17/review-hebie-chainglider-on-a-bullitt-cargobike/
Quote
Since making this adjustment the Hebie Chainglider is silent (providing well lubed) and while there is friction that you notice if back pedalling I have not noticed any drop in speed.

http://www.bikeforums.net/showthread.php/309639-Hebie-Chainglider-Pics Post #7
Quote
The chainglider DOES make some noise. It is tolerable but if a silent bicycle is your goal, look elsewhere. It is a faint but audible dragging sound.

When I got it back from the bike shop, the chainglider added noticeable drag/friction to the drivetrain. It was a deal breaker. Once I got it home, I lubed the heck out of the chain. Now it is much more acceptable. You have to have a lot of lube to keep the chainglider from robbing your efficiency.

I like it overall, but it isn't perfect. A bit of noise, and a tiny bit of drag once it is properly lubed.

Same link, Post #10:
Quote
That thing had a LOT of drag before I oiled the !@#$ out of it.

Same link, Post #15:
Quote
Here's the trick, lube the hell out of your chain, pour lube in the case before you install it, and then after you put it on pour more lube in the small fill hole.

...and a number of German- and Dutch-language sites where the Chainglider has been reviewed. It appears from those comments the Chainglider's silence depends at least in part upon chain lubrication. For example:

http://newsgroups.derkeiler.com/Archive/De/de.rec.fahrrad/2006-05/msg01856.html Post 13May2006 by Michael Kobzan:
[Translated:]
Quote
How to minimize the background noise?

No easy question to answer. There are several possible
causes for the development of noise when Chainglider...chain lubrication. Lubricating the chain when Chainglider two reasons: a). so that water entering the chain nothing can harm and b). reduces the fat noises significantly. Tip: a hint of fat on the flanks chainring - there, where the guard makes contact - works wonders.

...And a number of buyer's comments in German and Dutch at vendors' sites, indicating any noise -- slight though it may be -- is reduced with adequate-to-generous chain lubrication.

In this same vein, there is a recurrent theme where users/owners ponder if Hebies recommendation of "grease" to lube the chain should be taken literally in light of reducing Chainglider noise. Some feel any existing drivetrain noise is actually reduced by the damping effects of the Chainglider's case, while others feel some need to reduce friction between the Chainglider and chain through use of lubricants, which they report as effective.

Nowhere in the discussion can I determine if there is a correlation between fitting the Chainglider too tightly and noise (I would presume a direct correlation). If the case is simply fit too tightly and is bearing unduly on the chain, it would explain why lubrication might reduce noise that would not be present if the chaincase was fitted properly. This could explain the difference between your experience and that of (some) others in finding a direct link between lubricant and noise.

 I'm hoping for an experience like yours! Your ears are well-tuned from your many years as an audiophile and music reviewer, and I trust your assessment, Andre.

All the best,

Dan. (...who is being thorough before spending his money)