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Spot Bikes belt-drive Carbon Drive System bikes

Gates Carbon Belt

Perhaps the most fascinating products I’ve seen at the show so far are the Spot belt-drive bikes. Spot brought 40 belt drive bikes to the outdoor demo and folks were riding around in them all day in the desert conditions. The feedback was very positive so I paid Spot a visit to get a deeper understanding of this new drivetrain.

Why now?

Folks have been dreaming about belt-drive for years. It has never come to fruition until now since a suitable belt has not been available until last year. Josh Ogle from Jericho made a big splash a few years ago when he showed off to Interbike with a belt-drive bike. But, the drivetrain was not reliable because there was no available belt ready to take the forces of the bike. But finally, a company called Gates Corporation released their belt drive system for bikes called the ‘Poly Chain Carbon Belt Drive System’

More info: http://www.gatesprograms.com/carbon/

The advantages of a belt drive system are low weight, noise and maintence. The weight of the belt is about 55 grams while a typical chain of the same length is about 255 grams. The system should be quieter as it experiences no squeaks, pops and rattles. And finally, the belt never needs to be oiled. It is more durable than a chain and never stretches. It’s lifespan is around 8000 miles.

On the minus side, no derailleur is possible with a belt drive so applications are limited to singlespeed and internal gear hub systems. Another difficulty is the frame needs to be specially designed for this system and allow a break in the chainstay. Since the belt cannot be broken, the frame needs to allow inserting of the belt in the chainstay. Finally, a belt drive system like this limits the user to very few sources for front and rear ‘belt wheels and cogs’.

One of my big concerns about a belt drive system is power loss. If I lost 10-20% of my power due to drivetrain friction, that would be a deal-breaker for advanced mountain bike riding. My test riders however could not detect any power loss in the 30 minute test rides. And more important, Spot Bikes hired and independent company to compare their belt drive drivetrain with a standard chain drive system. The test involved using a motor connected to a Powertap power meter on two bikes. The findings were there’s no power differences between the output of the two systems. Please see the document below for an excerpt of the study.

Belt Drive study

Ok, but where’s the bikes? If you are singlespeeder, 29er, commuter, cyclocrosser, you have reason to rejoice.

The bikes are beautiful and they are nicely spec’ed. Expect more details coming soon.

Longboard – singlespeed 29er

Longboard

Black and Tan – singlespeed cyclocross

Spot Bikes Black and Tan

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  • James says:

    A nice new clean chain may be 98.5% efficient, but I know the dirty old stretched chains that I have on all of my single speeds right now are no where near that level of efficiency. A clean, virtually maintenance free drivetrain is appealing. If the carbon reinforced belt is as durable as is claimed, I think it makes a lot of sense, especially for commuting bikes.

  • fcebedo says:

    francois
    09-27-2007, 11:39 PM
    It is a show highlight for me!!!!

    http://reviews.mtbr.com/interbike/spot-bikes-belt-drive-carbon-drive-system-bikes/
    http://reviews.mtbr.com/interbike/files/2007/09/img_0419.jpg

    Surprisingly, the belt wheels are bored-out in between the gears. This allows for silent operation, better grip and easier cleaning.

    fc
    dRjOn
    09-28-2007, 12:19 AM
    is the belt at high tension?
    francois
    09-28-2007, 12:47 AM
    is the belt at high tension?

    No. As you can see in the photo, it takes very little tension to shape the belt into the drivetrain. The bikes I saw didn’t have the belt at a high tension.

    I’ll try to get more data on the tension specs.

    fc
    SlowerThenSnot
    09-28-2007, 03:29 AM
    That is just so neato! I wonder if it would work on a fixedgear applacation?
    arkadi
    09-28-2007, 04:02 AM
    This is pretty neat. I wish there were some way to break the belt and retrofit to existing bikes that I own. Though that Spot Black & Tan CX bike would be a nice acquisition.
    endure26
    09-28-2007, 04:09 AM
    I’d see no reason it couldn’t be used fixie. The belt and pulleys should be able to handle the torque created – forward or backward – from spinning it fixed. Obviously you’d need a special cog. The spaced required to accomodate the width of the belt might be an issue (cog + lockring). Might be easier to use one that mounts to an IS disc hub.

    I’ve dreamed of belts since my days as a BMX’er in the early ’80′s. A chain drivetrain consumes a lot of wasted energy through friction. A belt is so smooth and quiet.

    I was also wondering about how they would avoid build up of mud or debries. Hopefully the holes in the drive pulleys help accomplish some clearing.
    heythorp
    09-28-2007, 04:47 AM
    there have been a few ride reports on the spot.

    I saw one guy say it slipped on the hills and that when he brought it back to Spot they said it must not have had the right tension. The reviewer seemed to not believe their response.

    The other 2 ride reports I have read have been positive and both reviewers said there was no slip. Unfortunately these were quick little ride reports so I don’t really know what they add up to.

    Its great these guys go out there and run around and test everything they can get their hands on, but I would rather people spend longer time with fewer products to get a better understanding of how the new stuff works ( yes i know time is limited so others can try it too, but manufacturers could “hold” one bike for longer test rides and have it available 2 or 3 times a day).

    I like the belt drive, I am a bit surprised this systems hasnt popped up on townies and such. Putting a break in the frame probably isn’t the best for marketing.
    Andrew-FSR
    09-28-2007, 06:12 AM
    Couldn’t you use elevated chainstays to avoid having to break the frame at the dropouts?
    crashtestdummy
    09-28-2007, 06:22 AM
    There was a rider at the Outdoor Demo who got a flat on a Spot out at the CCCC NMBP canopy between trails 2 and 3. He had to pull the tube out of the tire and fix it while it was on the bike. Couldn’t figure out how to get the wheel off.
    dRjOn
    09-28-2007, 06:23 AM
    there is a spot cx tyred 29er fixie there….its white and small..
    WarPigs
    09-28-2007, 06:32 AM
    Couldn’t you use elevated chainstays to avoid having to break the frame at the dropouts?

    did anyone patent that design? i doubt spot want to be specialised!
    mallen
    09-28-2007, 06:33 AM
    There was a rider at the Outdoor Demo who got a flat on a Spot out at the CCCC NMBP canopy between trails 2 and 3. He had to pull the tube out of the tire and fix it while it was on the bike. Couldn’t figure out how to get the wheel off.

    The belt drive is really cool, but it sounds like they need to start working out the real world issues that the system would face once the general public started using it. Just like my first flat tire with my King bolt rear hub, I didn’t have a big enough allen wrench to get the wheel off! :madman:
    WarPigs
    09-28-2007, 06:38 AM
    The belt drive is really cool, but it sounds like they need to start working out the real world issues that the system would face once the general public started using it. Just like my first flat tire with my King bolt rear hub, I didn’t have a big enough allen wrench to get the wheel off! :madman:

    i dont think that is really a problem, you should have brought your tools along, thats why QR was invented.
    mallen
    09-28-2007, 06:49 AM
    True. What I was trying to say is that problems that are not discovered under normal testing have a way of being discovered once the product is used in a real world setting.

    As for Patents, check out Google’s Patent search. Looks like Dayco Corporation got a Patent for a belt drive bike back in the late 70s. http://www.google.com/patents?q=bicycle+belt+drive&btnG=Search+Patents
    Endomaniac
    09-28-2007, 07:00 AM
    Didn’t Jericho build some belt drive bikes a few years ago?
    Does anyone remember their issues with the system?

    As soon as I saw these I thought “elevated chainstays” ala – Yeti Ultimate, Alpinestar, and whatever those old Fishers were called.
    ~martini~
    09-28-2007, 07:05 AM
    The ride reports I’ve seen on it say that the bigger amongst us will most likely have the drive skip. Too much power/weight. The smaller folks report not having the skip issue.

    As for being able to change a flat out – why the hell do you need to take the belt off to change a flat? All you need to to do is slip it off the cog, and slide the wheel out of the drop outs! Must’ve been a floor jockey who got the flat or something. A competent mechanic would’ve figured it out in a heartbeat.

    As for the drop out. Gates is making them available in Steel and Ti so all the custom shops can make belt drives too. This is by no means limited to Spot, though they were smart enough to jump on this first for Interbike.
    sparrow
    09-28-2007, 07:06 AM
    endure26:
    “I’ve dreamed of belts since my days as a BMX’er in the early ’80′s. A chain drivetrain consumes a lot of wasted energy through friction. A belt is so smooth and quiet.”

    I think a chain/cog combo has proven to be one of the most efficient methods to transfer power ever invented. Even without proper lube, and in cross chain scenarios, I seem to recall seeing under 3% loss of energy. Straight line chain (as possible on a SS) and proper lube puts that sucker up around 98%+ efficient!

    If a belt drive can simply match that level of efficiency AND lower weight and maintainence, it could sell to SS. Chains are pretty darned proven at this point, though.
    lanceh
    09-28-2007, 07:16 AM
    seems like a cool setup for someone who never changes gears but having to have a different length belt for each cog size sucks.

    also, wouldn’t the break between stays create an uneven left of stiffness between right and left sides?
    francois
    09-28-2007, 07:24 AM
    Here’s a photo of the their fixie. It’s the anti-bike.
    - belt drive
    - disc front brake
    - sloping top tube
    - flat bars.

    I believe this bike is $800 complete bike!!

    Some thoughts on the issues brought up:

    Jericho made a couple of bikes. The biggest issue was slipping under loads. Josh Ogle waited and waited for this belt from Gates Corporation but it did not come until last year and he’s been out of the business. Jericho was just ahead of his time.

    There were a couple of reports of two bikes that went out of adjustment during the demo days were they had at the bikes out. Hundreds of people rode these bikes so I’d like to hear from more riders who tried them.

    There was some squeaking in the drivetrain in the dusty conditions of the desert. Spot said they hadn’t expected this. Cleaning the belt was easy as spraying it with the water bottle.

    Normal maintenance of the belt is by brushing it with a stiff brush to get any debris off.

    They say the belt excels in muddy, cyclocross conditions! I’m skeptical but would like to see it.

    Spot has all new management and has had an infusion of cash. I heard a rumor that Christina Begy is one of the owners now. The have a full custom us made bike for $1200 and a 6 new bikes manufactured in Taiwan.

    We’ll have one of these belt drives at mtbr soon!!!

    fc
    mtroy
    09-28-2007, 07:34 AM
    I think it is neat. But why is it so much better than a chain? Unless someone has efficiency numbers to show it is way better than a decently lubed chain…hmmm. I guess it would be quieter and cleaner.

    I know a chain loses some of its magic as it dries out or gets muddy. Maybe that is it.

    Anyway, not being a negative ninny, just wondering what the deal is. Personally I would have liked to try it.
    tl1
    09-28-2007, 07:36 AM
    Better than a chain that is? Is it lighter, does it last longer?
    francois
    09-28-2007, 07:41 AM
    Better than a chain that is? Is it lighter, does it last longer?

    Read this:

    http://reviews.mtbr.com/interbike/spot-bikes-belt-drive-carbon-drive-system-bikes/

    The belt weighs 55 grams and lasts 8000 miles.

    fc
    mtroy
    09-28-2007, 07:47 AM
    Read this:

    http://reviews.mtbr.com/interbike/spot-bikes-belt-drive-carbon-drive-system-bikes/

    The belt weighs 55 grams and lasts 8000 miles.

    fc

    Ah. Thanks.
    heythorp
    09-28-2007, 07:55 AM
    seems like a cool setup for someone who never changes gears but having to have a different length belt for each cog size sucks.

    also, wouldn’t the break between stays create an uneven left of stiffness between right and left sides?

    no reason you couldnt have gears, might need a specially made Rolhoff hub, but I wouldnt count gears out yet.

    I read one reviewer say they used a bigger? hub then normal to accommodate the gear.
    heythorp
    09-28-2007, 07:57 AM
    As for being able to change a flat out – why the hell do you need to take the belt off to change a flat? All you need to to do is slip it off the cog, and slide the wheel out of the drop outs! Must’ve been a floor jockey who got the flat or something. A competent mechanic would’ve figured it out in a heartbeat.

    As for the drop out. Gates is making them available in Steel and Ti so all the custom shops can make belt drives too. This is by no means limited to Spot, though they were smart enough to jump on this first for Interbike.

    Yes changing a flat shouldnt be any different however changing the belt is the issue without the break in the drops.

    Now what, if you take this bike out on the trail you carry an extra belt? Man that just wont fit in my jersey pocket.

    I still think the best application for this are townies and the chopper looking things
    ncj01
    09-28-2007, 08:02 AM
    Yes changing a flat shouldnt be any different however changing the belt is the issue without the break in the drops.

    Now what, if you take this bike out on the trail you carry an extra belt? Man that just wont fit in my jersey pocket.

    I still think the best application for this are townies and the chopper looking things
    Belts are a lot more durable than chains.

    Take for instance there are motorcycles, including sport ones that use belts. Figure 5-600 pound bike with 100 HP, they pretty much don’t wearout or break the belts.
    francois
    09-28-2007, 08:08 AM
    no reason you couldnt have gears, might need a specially made Rolhoff hub, but I wouldnt count gears out yet.

    I read one reviewer say they used a bigger? hub then normal to accommodate the gear.

    Yes, no derailleurs allowed but internal hubs gears are the ticket.

    Commuter/hybrid applications for this are golden!

    fc
    heythorp
    09-28-2007, 08:16 AM
    This quote kills me:

    “But finally, a company called Gates Corporation released their belt drive system for bikes called the ‘Poly Chain Carbon Belt Drive System’”

    I know it doesnt say it, but to me it reads:

    finally, some company i have never heard of called Gates corporation”

    Gates is a huge company. again i know its not what it said but its how i read it.

    this is from the gates site pretty cool actually

    A meat processing plant moving 10,300 hogs through the line every day measures downtime in 1/10th second intervals, because a single minute can cost thousands of dollars in lost productivity. Converting 500 roller chain drives to Poly Chain belt drives with stainless steel sprockets and bushings cut maintenance expenses by 90%, saving an estimated 2,000 hours per year. Add it up, and chain comes up short.
    pacman
    09-28-2007, 08:17 AM
    Read this:

    http://reviews.mtbr.com/interbike/spot-bikes-belt-drive-carbon-drive-system-bikes/

    The belt weighs 55 grams and lasts 8000 miles.

    fc

    Color options?
    heythorp
    09-28-2007, 08:27 AM
    Belts are a lot more durable than chains.

    Take for instance there are motorcycles, including sport ones that use belts. Figure 5-600 pound bike with 100 HP, they pretty much don’t wearout or break the belts.

    Yes but I am thinking in terms of 100 mile races and the like. (sorry thats what I am into right now so all of my thoughts revolve around that). I don’t think I am going out on one of those without the ability to fix my drive train. I don’t carry much on the trail, as a matter of fact I rarely bring more than a tube and co2, but on the long haul stuff you have to bring more stuff.

    I can’t remember the last time a belt on my car broke either but that doesnt mean it wont happen. Havent broken a chain in 15 years either, still bring a chain tool out on 100mile races though.
    Speedub.Nate
    09-28-2007, 09:22 AM
    Different belt lengths available?

    I’ve got an elevated chainstay headed my way, and I’d love to try this with a Speedhub.
    RPK3
    09-28-2007, 09:23 AM
    The Spot 29er was my favorite ride of the Dirt Demo. But not because of the drive train. There were other bikes that I wanted to like more but I was in love with the handling of the Spot. It was the only bike that I took for 3 laps, hitting both loop 2 and 3. I went back to the Spot tent after my 1st lap because there was so much noise from the drive train. They sprayed the belt with some water and sent me back out. They noise stayed away for a half a lap and came back. I watered it before my 3rd lap from my camelback and again it was quiet for a while. The conditions out in Bootleg Canyon were very dry and dusty. There were quite a few Spot bikes out on demo and some seemed quiet but the one I rode was squeaking away. And the Hayes Stroker brakes squealed even louder, worst disk brakes I’ve ever used. They had poor modulation and horrible noise on both the bikes that came with them (Spot and Lenz).

    And yet I stayed out on the Spot for a 2nd and 3rd lap. I’ve never even ridden a single speed before! The bike felt light and the drive train, responsive. I made all of the climbs and it’s handling was magical. The frame had a nicer “steel” feel than my fancy tubed,853 Gunnar. It felt reasonably compliant for a hardtail and it just had the best balance cornering and in the air. Maybe it was the light weight, maybe it just fit me better than any other bike I’ve ever ridden, but I was just so comfortable in the air, popping off every bit of rise I could find, kicking the bike into a “mini” tail whip to either side. This is not something I’ve ever done on other bikes. Nor was I doing it on the Behemoth, Sultan or Mamasita that I rode on the same trails. And while I did air bigger (in a straight line) over the one real tech drop on the #2 loop, on both the full sus bikes, the spot was the highlight. And this was with a noisy drive train and those horrible brakes. I also like the Manitou fork on the Spot way more than I was expecting, with nice damping and and easily adjustable platform, it was a good match.

    The bike had Small Block 8 tires on it front and rear. I had not ridden this tire and did not think it would be a good front tire for the dry loose conditions. But as long as I rode moto style, (bike down) not road race (shoulder down), the front tire would hook up at speed. As a motorcycle road racer, cornering speed is my strongest skill in the dirt. It was quite crowded out on the loops so I kept slowing down to get some space ahead and then let the bike run again. Fun!

    I’m 6′ and weigh 175lb plus riding gear. I did not have any trouble with the belt slipping. I’ve got real long legs for my height and waited the 20 inch frame. It was a pleasure to have the bars just above seat height for a change and the reach was not too long. I think that this size frame may have been set up with more belt tension for heavier riders than the 17.5. This extra tension plus all the dust is my hypothesis as to why my drive train squeaked and others did not. I felt no loss of power, in fact the bike felt quite snappy, but when I turned the cranks backwards by hand, they had more resistance than I expect. The bike felt incredibly light for a chromolly frame. The belt drive must be much lighter than the equivalent chain setup.

    I don’t usually ride in such dusty conditions and hope that the drive train will not be an issue. I am planning on getting one of these bike for my stable. As you can tell from the length of my review, this bike had me pumped!
    francois
    09-28-2007, 09:36 AM
    Color options?

    I’ve already special ordered my white belt. Cause white is the new brown, which is the old black.

    fc
    francois
    09-28-2007, 09:38 AM
    Different belt lengths available?

    I’ve got an elevated chainstay headed my way, and I’d love to try this with a Speedhub.

    Different lengths, yes. The standard length is designed to fit a 32-16 to 32-22 equivalent gearing (don’t quote me on that).

    Beyond that different lengths are available. Belts are around $80.

    fc
    francois
    09-28-2007, 09:40 AM
    ….

    Nice info man. I’d like to use it in my interbike coverage if that’s ok with you.

    fc
    francois
    09-28-2007, 09:44 AM
    did anyone patent that design? i doubt spot want to be specialised!

    This belt-system is a platform. So Gates Corp. wants as many manufacturers as possible using it.

    Spot will be selling this system to other manufacturers as the Carbon Drive system. It’s a package that includes belts, dropouts and belt wheels. Smart move as they’ll make money on other companies’ belt bikes.

    fc
    RPK3
    09-28-2007, 09:54 AM
    Nice info man. I’d like to use it in my interbike coverage if that’s ok with you.

    fc

    Fine with me. Just list the source, RPK3. :thumbsup:

    Zach
    canyoneagle
    09-28-2007, 11:29 AM
    RPK3:
    Which Gunnar do you have? I’ve been heavily considering a custom Ruffian 29er, but have also been considering a Spot frame. Your comments on the handling have me intrigued………….
    In the same vein, did you ride the Vassago Jabberwocky SS? If so, I’d be keen to hear your relative impression.

    Finally, on a general note, from what I could see from those pics, the rear cog appears to be open on the sides (no guides for the belt). Hmmmm………

    Thanks,
    Michael
    WarPigs
    09-28-2007, 11:38 AM
    This belt-system is a platform. So Gates Corp. wants as many manufacturers as possible using it.

    Spot will be selling this system to other manufacturers as the Carbon Drive system. It’s a package that includes belts, dropouts and belt wheels. Smart move as they’ll make money on other companies’ belt bikes.

    fc

    sorry, i meant the design of elevated chainstays ala alpinestar design and certain FS bikes with such designs.
    pinkheadedbug
    09-28-2007, 11:41 AM
    This plus a Rohloff seems like it would be nice.
    GeoKrpan
    09-28-2007, 01:51 PM
    Delta CDrive bicycle with belt drive, elevated chain stays, and Sturmey Archer 3 speed rear hub.
    This bike has been around for a couple of years.
    http://www.deltacycle.com/product.php?g=69#
    burner
    09-28-2007, 02:14 PM
    as to the strength of the belts, Spot had in their display a huge dressed up touring style harley hanging in mid air, supported by only of these belts.
    ajbuilder
    09-28-2007, 04:19 PM
    Gates is the #1 producer/supplier of automotive belts…….which are only like $20-25 each, …..so why $80 for a smaller belt? ridiculo! Quality is top notch. I don’t like the idea of a split-frame, though. Someone has to have tried this in the past and the chain had to have prevailed is what I’m thinking, but kinda nifty none the less!
    Fat Elvis
    09-28-2007, 05:03 PM
    Gates is the #1 producer/supplier of automotive belts…….which are only like $20-25 each, …..so why $80 for a smaller belt? ridiculo!

    It’s called economies of scale.
    chequamagon
    09-28-2007, 05:17 PM
    I was the one that rode the white 20″ Spot demo bike at the dirt demo, and I was the one that reported belt slipping.

    I weigh 250, and I am a former Alpine ski racer, so I guess you could say that I have tree-trunks for thighs. I also have a beer gut.

    I am not a single-speeder, so I dont anticipate the hills like I should, and some hills I was just torquing up at the greatest I had ever put out. All power, no spin.

    I felt the belt skip regularly. It makes a ping. It did it 7-8 times on the worst hill that I experienced, and probably 20 total skips in the lap.

    When I went back to the booth, their first response was the maybe the hub was bad. The hub was a King. I went over to the King booth, told them that, in which they laughed because if you know a King hub mechanically, it is impossible to skip a cog. If it skipped at all, it would fail entirely. In addition, the King rep there also reported that he had felt a belt skip too during testing.

    I went back to Spot in which this time I confronted them with these facts, and this time they said that the belt must have been out of adjustment. I still feel this is another BS because you can see the tensioner system they are using, and I did check the tension many times when I could feel the skipping, and it was at the same tension as all the rest of the fleet.

    Now, on top of all this, I thought the system was great. What you say? After all that? Yes, it was quiet, simple and most importantly, it didnt transmit shock to the legs like a chain does. I thought it rode wonderfully. Hopefully they can figure out the skipping.

    I felt bad for Spot. They are trying hard. I am really skeptical because of their BS responses to the issues. If they just said “yeah, we know and are working on it” that would be a good response. But the excuses and blaming King are just not acceptable.
    mtroy
    09-28-2007, 05:39 PM
    I was the one that rode the white 20″ Spot demo bike at the dirt demo, and I was the one that reported belt slipping.

    I weigh 250, and I am a former Alpine ski racer, so I guess you could say that I have tree-trunks for thighs. I also have a beer gut.

    I am not a single-speeder, so I dont anticipate the hills like I should, and some hills I was just torquing up at the greatest I had ever put out. All power, no spin.

    I felt the belt skip regularly. It makes a ping. It did it 7-8 times on the worst hill that I experienced, and probably 20 total skips in the lap.

    When I went back to the booth, their first response was the maybe the hub was bad. The hub was a King. I went over to the King booth, told them that, in which they laughed because if you know a King hub mechanically, it is impossible to skip a cog. If it skipped at all, it would fail entirely. In addition, the King rep there also reported that he had felt a belt skip too during testing.

    I went back to Spot in which this time I confronted them with these facts, and this time they said that the belt must have been out of adjustment. I still feel this is another BS because you can see the tensioner system they are using, and I did check the tension many times when I could feel the skipping, and it was at the same tension as all the rest of the fleet.

    Now, on top of all this, I thought the system was great. What you say? After all that? Yes, it was quiet, simple and most importantly, it didnt transmit shock to the legs like a chain does. I thought it rode wonderfully. Hopefully they can figure out the skipping.

    I felt bad for Spot. They are trying hard. I am really skeptical because of their BS responses to the issues. If they just said “yeah, we know and are working on it” that would be a good response. But the excuses and blaming King are just not acceptable.

    Interesting. Well, maybe it will not be the best for Clydesdales or uber-power riders. Sounds like time will define that line a bit better as to who it works for and who it does not. I would sure consider it.
    Soupboy
    09-28-2007, 07:31 PM
    Wondering why the rear cog has a guide to the inside and the front cog has a guide to the outside.

    Are you to set it up slightly off from straight? Or, are the teef of the cogs canted to a degree front vs. rear?

    I love stuff like this.
    DirkSSter
    09-28-2007, 09:21 PM
    Here’s a little marketing video I found…

    http://www.youtube.com/rodblackhurst
    PattD
    09-28-2007, 10:27 PM
    I talked to Chris from Spot at the show and that was his first question when the system was done…he immediately ran out…took his bike with the new drivetrain into the mud…got it as mucked up as he could…and proceeded to ride away. He said it’s pretty much self cleaning. After a couple of spins of the cranks, the mud was gone and it was completely quiet and smooth. I’m in CO near Spot and have plans to swap him a bike for a day to try this out. I’ll post here when that happens…give me a few weeks. PD
    pacman
    09-28-2007, 10:59 PM
    Can the belt be damaged if the outside scrapes across rocks?
    Speedub.Nate
    09-28-2007, 11:57 PM
    Here’s a little marketing video I found…

    http://www.youtube.com/rodblackhurst

    Huh, weird… my volume dropped out at about 1:08 ;)

    Shoulda been on rollers. Woulda looked cooler.

    I’ve got to shoot Spot an email.
    pimpbot
    09-29-2007, 01:42 AM
    I’ve dreamed of belts since my days as a BMX’er in the early ’80′s. A chain drivetrain consumes a lot of wasted energy through friction. A belt is so smooth and quiet.

    Chains loose very little if you take out the derailleur. It’s the chain wrapping around tiny cogs or pullies that adds friction. I’m not sure a belt will actually be lower in friction. Keep in mind, those little teeth still have to mesh in the sprocket. I’ll bet a belt is lower, but the friction in a SS drivetrain is super low already, so I’m not convinced there is hardly anything to be gained there.

    Quiet is good, tho!
    Rainman
    09-29-2007, 02:33 AM
    Belts are a lot more durable than chains.

    Take for instance there are motorcycles, including sport ones that use belts. Figure 5-600 pound bike with 100 HP, they pretty much don’t wearout or break the belts.

    I had a belt on my Harley. It never slipped or required any maintenance. It took the power easily, and was waaaay quieter than a chain.

    I wondered for a long time why belts weren’t used on bicycles. It seems like a great idea.

    R.
    francois
    09-29-2007, 09:35 AM
    Wondering why the rear cog has a guide to the inside and the front cog has a guide to the outside.

    Are you to set it up slightly off from straight? Or, are the teef of the cogs canted to a degree front vs. rear?

    I love stuff like this.

    It does seem odd. It might be to simplify manufacturing. Two guides on each side seems like the obvious choice.

    My guess is the belt corrects and straightens itself out. There seemed to be no issues with belts derailling at the outdoor demo.

    fc
    canyoneagle
    09-29-2007, 11:05 AM
    Like the video.
    francois
    09-29-2007, 02:56 PM
    Dealers were buying the demo Spot bikes left and right at the outdoor Demo itself. Spot then realized they could be completely without demo bikes after the show so they hung on to a few.

    fc
    grawbass
    09-29-2007, 08:03 PM
    as to the strength of the belts, Spot had in their display a huge dressed up touring style harley hanging in mid air, supported by only of these belts.

    How many belts? One hundred? ………………………………..jk ;)
    grawbass
    09-29-2007, 08:06 PM
    Now, on top of all this, I thought the system was great. What you say? After all that? Yes, it was quiet, simple and most importantly, it didnt transmit shock to the legs like a chain does. I thought it rode wonderfully. Hopefully they can figure out the skipping.

    I have a feeling they need to work on the tooth profile to fix the skipping.
    grawbass
    09-29-2007, 08:16 PM
    Keep in mind, those little teeth still have to mesh in the sprocket.

    Also the flexing of the belt requires more energy than the bending of a chain. The belt suffers from the same effect that creates rolling resistance in tires, namely flexing and creating heat. A chain is allowed to “bend” with bushings, creating less heat and wasting less energy.
    francois
    09-29-2007, 08:23 PM
    I have a feeling they need to work on the tooth profile to fix the skipping.

    Maurice from Dirt Rag could not make this belt skip, from what I hear. He’s a big human being :D .

    The variables for this drivetrain are belt width and belt tension. They said they were on their 9th different belt width until they came up with this one. Too narrow and the belt would skip under load and/or require too much tension to hold.

    The other variable is belt tension. It seems like if you press down on the belt to the chainstay, it should bend down about 3/4 inch. Spot didn’t have tension measuring tool yet for these belts so they said they were using a harmonic listening tool and plucking the belt for the right tone.

    fc

  • Allen says:

    I agree, the 20″ Spot demo was the best of the 2 days for me. Absolutely lovely handling and I was amazed when I got back…all I remembered hearing was the sound of the tires on all the different surfaces! I’m 224lbs and had zero problems with skipping and I wasn’t gentle on the hills. One thing, the Harley they had suspended @the indoor venue used one of the belts…one with only 1/4 the # of aramid fibers or whatever the “tech” belt material is. Truly impressive and a great rollout for Spot!

  • Keith Walker says:

    As a mechanical engineer, I have to laugh at bicyclists’ conventional wisdom sometimes. To think that a chain is better than a Gates belt is an absurd concept.

    All Harley Davidson motorcycles and Buell sport motorcycles (and some BMW cycles as well) use Gates belts for power to the rear wheel. If you know anything about Harley engines, they produce more torque than most japanese motorcycle engines – that means more stress on the belt than what a chain driven Japanese sport bike would see.

    Also consider that the bulk of automobiles on the road today have belt drive for the camshafts (timing belt). If a cam belt broke, the engine is potentially destroyed. How many times do you hear of a belt failure on a car?

    This is to say that a properly engineered belt system will not skip teeth and is more durable than a chain.

    I would tend to believe that the belts are skipping, but that is no fault of the belt itself – the culprit is the proprietary sprockets – it looks as if the sprocket in the photo above has slots where material is missing – most likey to clean out mud. The missing material probably leads to the rear sprocket teeth flexing enough for the tooth to bend, then the belt jumps a space or two.

    If you have a fixie or street bike, these sprockets could be solid, like the CDrive by Delta Cycles.

    The belt flex issue is also valid. There is a set amount of energy that is required to flex the belt. Is it more than a chain? I don’t know. I would be willing to bet though that with the weight saving you get from the belt system, there is a net gain in riding efficiency.

  • James says:

    with the break in the frame why not have a little piece of material that fills the gap and can be uncliped or unscrewed for belt replacement “if and when needed” that way the bike will still be full rigid
    and yeah i’ve waited to see belts on a pushie for a long time, since i saw a belt drive on a motorbike as a child

  • Gordon says:

    I think Spot should develop the same system for the rear as Cannondale has developed for its Lefty bikes. A single sided beefy chainstay would do away with the need for a break. Certainly Cannondale has demonstrated that a hub and spindle are durable under intense pressure.

  • Paul Kossa says:

    Does anyone know if this is compatible with the Rohloff Speedhub (14-speed internal derailer)?

  • Walt says:

    If anyone cares to follow along, I am (slowly) in the process of building a belt drive frame for myself:
    http://waltworks.blogspot.com/2008/08/belt-drive-project-initial-thoughts.html

    Don’t expect much progress until the MTB season is over, though. I prefer riding to working.

    -Walt

  • Dirk says:

    Biggest problem imo is the extra stress on the BB-and rear hub drive-side bearings and the body.
    The belt would last w.o. question but I guess one has to change the bearings more often so maintenance free could mean only for the belt and sprocket+chainwheel.
    Perhaps this issue can be solved with keramic bearings?

  • Chris says:

    Does anyone know the price of this bike? When will it be available?

    Chris

  • Jimbo says:

    Ordered my Spot Longboard today. Should arrive Friday (please!). I’m so stoked about this. I’m a winter commuter in Edmonton, Canada, and this should be a good bike for that. If you know Edmonton knows how rough winters can be (try minus 39 C – my coldest day). Last year I rode my TriCross Comp, and it did great, but I probably took a couple years off the drive train. Front shocks should help with the bone jarring caused by ice ridges and divots on the uncleared paths. I usually stayed in one gear anyway in winter, because I didn’t want to risk anything.

    I’ll post and let everyone know how it works for me. Thanks for all of the info, which really helped me make my decision.

  • Pablo Mac says:

    I think my Cannondale Prophet and an internal gear rear hub would make the perfect belt-drive full-suspension test bed.

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