[Closed] Belt-Drive Full sus update

Chains are the future, belts as Saaaad. Or is it the other way round?

Sounds like your chainstay is either flexing or moving laterally due to pivot play.

Got a pic of how you mounted the snubber? How it's mounted is very important.

I'm sure it is the chainstays moving, but I thought a snubber would prevent the ratcheting, but its clearly not up to the job 🙁

[img] [/img]

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It started off with about 1mm clearance off the belt. And the black "spacer" is there to keep the pulley on the inner groove on the pin. My first attempt this evening saw it pop off into the other position. Design flaw I guess.

From an engineering point of view, that's a poor design. There's too much leverage on the plate.
It looks like there's just about room for a second, thin plate inside the drop out.
That would make the shaft effectively shorter.
The thin plate would be under tension, so wouldn't need to be particularly strong.
The existing outer plate would then be under compression, rather than a bending load, so would be adequate.

That snubber just looks wrong.

Try a homemade one out of L shaped alloy. 2 holes - one for the hub axle and the other for the derailleur bolt.

That will at least locate it properly.

Alternatively get a bit welded on the the sliding dropout to mount the pulley - it will reduce the bending leverage.

But probably the best thing is to cure what is causing the problem in the first place. Pivots or chainstay flex.

That snubber just looks wrong.

I tried a homemmade one using plate, but that just bent, but I agree, it needs more section to it.
Gates have suggested a sliding dropout with built-in Snubber, so less cantilever, which makes sense. So I'm looking at checking measurements of my dropout with the one they have designed.

And I know it might be flex in the pivots, which is a real shame as the A made so much sense 🙁

Can you shim the pivots up tightly? It's a shame you are having these problems - the Kona-A was a bike I had my eye on for a conversion.

Belt drive is really finicky for a conversion - it's bad enough on bikes designed for it 🙂 The advantages make it worth persevering though.

The latest version from Gates with the centre ridge looks to me like it will be able to handle a bit of misalignment better.

This bodged YESS tensioner did a good job on a very flexy bike - no slip and it didn't bend.

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The position of the pulley is not good though.

I just can't see why the belt would climb the teeth to such an extent with slight misalignment caused by chainstay flex - that's quite amazing. What are the torque limits on the belt and gear setup, and how are you pre-tensioning it?

the snubber needs to work where the belt engages the cog on the lower run, not behind - should be as per epicyclo's pic. or did yours bend back as it slipped?

James, the snubber has a little pin on the back that fits in against the b-tension screw ridge on the dropout, so its fitted as Gates requirements. Its positioned just where the teeth are fully engaged.
[url= http://www.carbondrivesystems.com/images/uploads/installation_1271411518.pdf ]see page 18 of this[/url] It also shows the ball-groove in the pin that i had to cover with a spacer to stop the pulley being pushed sideways.
I've asked Gates what forces were taken into account for the design, as they're clearly not suitable. If there's enough force in the belt to cause it to rise up the teeth, that's the force the snubber should resist in bending.
Apparently I'm the first person to bend one! Grrr!

coffeeking - the only to pretension those dropouts is to lever them as back as possible. I could try fiting a bigger cog (which would give me a lower gear ratio) as the belt length is fixed, but I'm not sure the extra tension would do the frame any good.
Ah, the life of a bodger...

james-o - Member
the snubber needs to work where the belt engages the cog on the lower run, not behind - should be as per epicyclo's pic. or did yours bend back as it slipped?

The 7 o'clock position is actually the best position because it allows the wheel to be removed without hassle.

I suspect the Gates snubber is made of Butterinium.

"Advantages make it worth persevering though"

I'm still curious what these are. What does it do that a single chaindrive doesn't?

Increases your niche ratio.

Big pack -5
Full suspension -5
Gears -10
Snigglespeed +1
Snigglespeed on a full sus +10
29er +5
650B +7
Alfine +2
Belt drive +10
29er snigglespeed full sus belt drive +999999999999 stw god!

These only count if you post at least once a day stating your current configuration. An extra +10 if you suggest you're going to try one of these configs and include the phrase "I think I'm crazy, but..."

29er snigglespeed full sus belt drive +999999999999 stw god!

I thought you got bonus points for a beard too?

Sam - lightweight and maintenance free. But the cost and faff only just makes it worthwhile. But I reckon as they get more popular, the cost will drop and availablitly of suitable frames will increase. I'm prepared to have a go at it to try and help things along.

lightweight and maintenance free

From what I've seen (which admittedly is not a lot) when considering it as a system - chain/belt, cogs/chainrings and frame any weight advantage is negligible.

Maintenance of a single cog bike is pretty minimal anyhow I find.

The advantage I [i]do[/i] see is cleanliness, which would be great for folding commuters people are taking on public transport. Or for folks who need to store a bike in the spare room, so the wife doesn't complain about grease on the carpet. However for a general mountain bike for the majority of people I don't really see much/any benefit.

True, the stiffer frame is likely to add a bit of weight, but the belts themselves are bonkers light.
I agree about ideal for commuters and not so for mtbs. But, i figure if it works on mtbs, then it'll have no problems on commuters.

Maintenance of a single cog bike is pretty minimal anyhow I find

And

Or for folks who need to store a bike in the spare room

I store my bikes in the spare room.

(sometimes)

😳

but the belts themselves are bonkers light.

how is the weight saved with wider sprockets at both ends ?

Maybe if you replaced the rubber belt with a metal one this wouldn't be a problem. You could even cut holes in the metal belt to let the cogs sit even deeper with the added advantage that mud would be pushed out. I am sure you could come up with some kind of linky thing to allow the metal to bend around the cogs.

Minimal, yes. But not non-existent.

Maintenance doesn't quite seem to be non-existent on your belt drive bike either, given you haven't managed to get it to work yet!

WCA, sounds like a good idea. Do you have a prototype you could show us? I'm running something very similar on my bikes and it's working fine, SS and geared. Slight addaptation of something which is comercially available (bought it from large Japanese company, just had to trim it to length and then join the two ends together to make a loop. They even make a particualr kind of tool which seems ideal for this)

😛

keep at it bandito
early uptakers always suffer while the niggles workout
eventually the luddites will realise that their rattly greasy old chain isnt as good as the latest belt drives and copy you

eventually the luddites will realise that their rattly greasy old chain isnt as good as the latest belt drives and copy you

the whole chain drive thing (particularly with derailleurs) is hopelessly Heath Robinson and it's a wonder it works at all - however it does seem to work better than all the alternatives...

the whole chain drive thing (particularly with derailleurs) is hopelessly Heath Robinson and it's a wonder it works at all - however it does seem to work better than all the alternatives...

I refer Mr. Barnes to exhibit A: the snubber, as seen above. 😉

isn't the whole idea of a derrailleur other than to change gears to keep the chain tight when the distance between the crank set and cassette increases/decreases when you enter into the travel of a full suspension bike? I may be wrong but how the hell is a belt meant to stretch to let you actually use the suspension?

I refer Mr. Barnes to exhibit A: the snubber, as seen above

meaning what exactly ?

isn't the whole idea of a derrailleur other than to change gears to keep the chain tight

no, it was invented about 100 years before rear suspension became popular, but it just happens to fulfill that function too!

Will the increased drivetrain tension not increase bearing wear rates?

[i]isn't the whole idea of a derrailleur other than to change gears to keep the chain tight when the distance between the crank set and cassette increases/decreases when you enter into the travel of a full suspension bike? I may be wrong but how the hell is a belt meant to stretch to let you actually use the suspension?[/i]

thats why hes using it on a kona A, the suspension on which pivots around the bb.....

Keep at it irbandito, any fule kno early adoptors gets all the slagging

how the hell is a belt meant to stretch to let you actually use the suspension?

simon - I believe PMJ is referring to the snubber itself being a bit Heath Robinson. Either that or he's just being a facetious c0ck. 😉

chiefgrooveguru - it probably will, which is why I'm following epicyclo's idea of not running it too tight and theoratically using the snubber keep the belt attached.

thats why hes using it on a kona A, the suspension on which pivots around the bb.....

ah right fair enough.

ts a Kona A. It doesn't matter. That's the point.

do you mean the pivot is coaxial with the BB ?

simon - I believe PMJ is referring to the snubber itself being a bit Heath Robinson

oh, right :o)

I'd love to get away from the derailleur system, that's why I tried a Rohloff, but unfortunately that wasn't designed for Lakeland aquabiking and had to be sent back to Germany once a year 🙁

roller chain 98.8 percent efficient, pretty good for 'heath robinson' the fact you need a 'nubber' for your elastic band says it all. Ask any 'proper' engineer. yup your flares get oil on them but i can live with that....

Just remember this is a conversion he is talking about, not a purpose designed frame, so if it doesn't work that just highlights the unsuitability of the frame for the conversion, not the deficiency of the belt drive system.

One thing that may work is to fill the chainstay with 16lb. expandable urethane foam which will stiffen it considerable.

A frame that works nicely with a beltdrive is a Pompino. Negligible lateral flex. The belt does not need a lot of tension so long as there is no flex. I use the same tension as I would for a chain. Only proviso is to get the alignment absolutely perfect. It makes for such a nice quiet ride that I no longer ride my Singular Peregrine with its noisy dirty chain.

Edit:
Weight - I weighed the single speed components that came off my bike and then weighed the belt dive parts. The belt drive was about half a pound lighter.

I'd love to get away from the derailleur system, that's why I tried a Rohloff, but unfortunately that wasn't designed for Lakeland aquabiking and had to be sent back to Germany once a year

😉

I tried a Rohloff for the same reason. Unfortunately I just didn't like it (weight distribution was all weird and I couldn't get used to it) so went back to derailleurs.

I tried a Rohloff too. It now lives in my attic. I wonder how many like that there are.

Went back to single speed.

The gear change on an Alfine is nicer.

AWSOME!

Love tinkering about with stuff. Good luck and I'll look forward to later posts.

Are there any post about internal gear boxes going about?

Ridefree!

OP : Is it slipping because of the load ?

Its only slipping when I really tank it, but I suspect its frame flex, rather than belt-stretch.

I have a Rohloff and an Alfine-8, like 'em both and can't wait to try the Alfine-11. My long term plan is to design and build bikes capable of running belt-drives with hub gears (and gear-boxes). This "experiment" is showing up some major things to think about that I wouldn't have otherwise found out.

And the reason for the full-sus? Easiest frame to convert in theory as the suspension linkages allow for easy frame splitting. Combined with concentric pivot/BB and sliding dropouts makes it ideal. Sort of.

Oh, I'm a "proper" engineer too 😉 letters after my name and evryfink.

And forgot to say, thanks for the support from the less-cynical amongst you! It means a lot.
The rest of you pessimistic buggers, watch out you don't fall off the edge of the world, it is round you know...

pessimism or pragmatism ? I want something that works with as little attention as possible.

Wish I had a Rohloff in my attic lol

Tho I do have a pompino and love a tinker 😉

simon - I was bunching you with the "supporters" 🙂

I aim for the ultimate maintenance-free bike...

I aim for the ultimate maintenance-free bike...

well, amen to THAT, but I want LOTS of gears too 🙂

internal gearbox is the long-term goal.
but i do wonder if there're other ways of doing it. Hydraulic motors?

This might fix the problem - new system - CenterTrack:

[img] [/img]

Oh i thought he was using that centertrack. It was at interbike wasnt it? This has surely got to be the way forward for a centertracked belt driven 11spd alfine snow floater to combat snowy puffers! float over the snow,dump the bike without having to clean and lube the chain,go back out for another lap.

::ponders for a moment:::

I just pictured it ridden at the puffer with snow crushing into ice between the teeth and the centretrack sprockets. I wonder how it would cope?

right,bedtime.

Centre-treck isn't available until late 2011 🙁

martinxyz - snow (and clay) are the only conditions Gates say the belt won't work in... But I want to find out 🙂 There are times when a chain won't work in those conditions either. But a centre-tracked Alfine does appeal. a lot.

There are times when a chain won't work in those conditions either.

I live in Dorset (predominantly clay) and can't say I've ever had a chain stop working. I've had the wheels clog up so they won't turn, but never the chain. I'd be interested if anyone else has had this problem...

martinxyz - Member
...I just pictured it ridden at the puffer with snow crushing into ice between the teeth and the centretrack sprockets. I wonder how it would cope?

Only be a problem if you were a woose and stopped - at which point packed snow could freeze solid. 🙂

Easily fixed by dropping the wheel and giving the belt a shake or two.

This might fix the problem - new system - CenterTrack:

As much as I'd like to belt drives working well (I have a Rohloff'd Chameleon) that groove in the belt looks like it will fill with mud & grit, stopping the bike after overloading the bearings.

There's plenty room for it to be squished out - just like a chain 🙂

I've got a mate who built (As in designed and welded up) his own frame. Mk1 was to see if he could do it, and there was the odd mistake. It works though, and looks good. I was talking to him last night on a ride and he really wanted to fit belt drive to his next Mk2 frame, and he's put a lot of research into it. However, he's concluded that there are too many shortcomings of the Gates belt drive, and seeing as they keep modifying it (Centre Track) to try and get it working properly, he's knocked the idea on the head.

Apparently the sprocket sizes are very limited too. The rear sporkcet has to be rather large to get enough 'grip' from the belt, menaing the front sprocket must be bigger.

I guess ideas like this must be tried or the world would be a boring place indeed, but right now, I'm not so sure it offers any adventage over a chain, to be fair.....

It does have issues, but ultimatley the bike needs to be designed for it, not converted. I'm converting mine because I thought it would be easy! as the frame lends itself to conversion a lot.
epicyclo - I don't think the chainstays need stiffening as such, they're big boxy aluminum, the flex will be from the pivots.

and as to proving the concept works, James Bowthorpe has done that.

and as to proving the concept works, James Bowthorpe has done that.

James Bowthorpe would have made full use of the gears to keep the pedalling load as light as possible to minimise fatigue throughout each of his 100+ mile days.
Any of you out there with singlespeeds, stand alongside the drive side of the bike and push a foot down hard on the pedal. Watch as the lower chain run develops up to an inch of slack. That's what a belt drive will have to cope with on a singlespeed.

Apparently the sprocket sizes are very limited too. The rear sporkcet has to be rather large to get enough 'grip' from the belt, menaing the front sprocket must be bigger.

So what? Few ss riders (or geared ones) need the clearance of a 32T, despite the proliferation of 2x9 etc.

Great to see the pioneers do their thing. I'd love to try belt drive, may even get a bike converted!

What I really want is a close ratio belt drive, which is about as niche as it gets.

Hydraulic motors?

Hydraulic motors have been done I believe. And because the 'drivetrain' is just a flexible hose, you can make 2wd bikes.

However it's very inefficient.

That's what a belt drive will have to cope with on a singlespeed.

but isn't the belt less "stretchy" and run under greater tension? The singlespeed part is redundant as belt gearing is out of the question.

There's plenty room for it to be squished out - just like a chain

What? - a chain has holes in it, a belt doesn't.

What? - a chain has holes in it, a belt doesn't.

but there's no sideways restriction...

James Bowthorpe would have made full use of the gears

Snubbers, tensioners, mechs. Ugh! Ugly!

Really, the belts need deeper teeth to run low tension then? Either that or holes for some pegs on the sprokets to run through, almost like a chain. Teeth could still handle power transfer, but the holes and pegs could prevent misregistration or skip. They would not significantly reduce longevity if they're only under load when you're 'tanking it' up a hill etc.

You could have a two part belt, side by side teeth with pegs holes, or like that centre align but with pegs protruding through central holes.

Heh, I may well claim intellectual property rights there 🙂

Not really the realm of the home bodger though 🙁

ir_bandito - Member
...I don't think the chainstays need stiffening as such, they're big boxy aluminum, the flex will be from the pivots.

snaps - Member
... a chain has holes in it, a belt doesn't.

Mostly Balanced - Member
...Any of you out there with singlespeeds, stand alongside the drive side of the bike and push a foot down hard on the pedal. Watch as the lower chain run develops up to an inch of slack. That's what a belt drive will have to cope with on a singlespeed.

I'm hoping to have a belt drive on the bike I use for the StrathPuffer so I'll be able to confirm (or otherwise) whether the belt works in muddy and snow conditions.

24 hours of that should be a decent test.

anotherdeadhero - Member
Snubbers, tensioners, mechs. Ugh! Ugly!
...Not really the realm of the home bodger though

I dunno about the home bodger, I'm definitely in that category 🙂

As far as deeper teeth - Schlumpf are doing a 14mm belt kit with some clever ideas to help with alignment.

I was more suggesting that machining up cogs, sprokets and manufacturing belts with deeper teeth, specific profiles and pegs was beyond the realm of a home bodger, even those with a works machining shop to 'borrow' during midday downtime 😉

the schlumpf kit looks like it has potential, but I think there's a weight penalty on the cogs.

and as for race testing, I really want to ride the A at Dyfi next year...

I thought the cogs for these belt drives were open, with sides? Therefore eliminating the need for that centre track thing?

http://christinibicycles.com/bikes-longtravel.php

I'm going to stick my neck out and predict that with 10 years we'll all have shaft driven gearboxes, raather than chains/belts/mechs/etc.
The above is the only (semi)shaft driven bike I know of at present, any others out there?
Weight may be an issue, but 10 years ago no-one was predicting 16Lb full suss race bikes. (have a look on the weightweenies site)

How would you fit 15 or so gears into a shaft gearbox?

Rohloff get 14 gears into a 'gearbox', although chain driven at present.

I really like the principle of this.

You'll have to excuse the perhaps over simplified thought on this but ......

Could you not just add to washers to either side of the rear cog to help "encase" it or have I completely missed the point 😳

Like this cog but obviously larger

[img] [/img]

Christini have been pushing their AWD system for ages (it may even be 10 years!) and I've never seen one in the flesh on the trails (I have 'bounce tested' one around a car park though) and none of the 'big boys' appear to have copied it.

Not saying that it won't happen, or some evolution of it from a true gearbox bike might make it more practical, but there must be a technical/cost/perception issue with it if it hasn't take off, in that guise, by now.

How would you fit 15 or so gears into a shaft gearbox?

Rohloff get 14 gears into a 'gearbox', although chain driven at present.

Indeed - a twin shaft g-boxx2 would get you to 14 speeds, 'Rohloff in a box' style.....

What about this 18 speed box?
[img] [/img]
[url] http://www.pinion.eu/en/ [/url]