[Closed] Belt-Drive Full sus update

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]

^^^ Nice!!!!!

that pinion looks excellent

combine it with a belt drive and itll be like riding the bike of the future, today!
[img] [/img]

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

When I said 'shaft driven' I meant a car or motorbike style one. Rohloff is an epicyclic gear system and is therefore inefficient in terms of power transfer.

The pinion thing could be either, I dunno.

the pinion box is a motorcycle style one but with 3 shafts not two to allow lots of gears without it getting too wide

Shaft drive is inherently inefficient as the drive has to turn thru 90 degrees twice. In motorcycles you loose about 10% of the power

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

strictly speaking you could fit other types of sprocket to the thread...

Rohloff is an epicyclic gear system and is therefore inefficient in terms of power transfer.

they claim ~96%+ efficiency - certainly the hub never got warm

I think the transmission of the future is chain drive, but totally encased in an oil bath chaincase like Sunbeams in the past or Katz bikes right now. We could run much lighter chains and sprockets.

However as long as we run exposed transmissions, belt is the way to go.

The advantage of a rear hubgear over gearboxes is that the torque is stepped down between the crank and the rear wheel so the gears can be lighter.

Doing a step down between the crank and a centrally mounted gearbox suffers from the lack of room to do it and also introduces another set of drivetrain losses.

If you don't have a stepdown then you need stronger gear components which is difficult to do without a significant weight penalty - probably close to 100% at a guess.

Any idea of the weight of those centre mounted gears?

That Pinion looks great.
Someone tell me one of those at the fron and a Rohloff at the back wouldn't work for a 252 speed( minus some overlaps probably, but we still count them in a 27sp system) bike? What would be the effective range there?

Half term again?

andrewh - Member
That Pinion looks great.
Someone tell me one of those at the fron and a Rohloff at the back wouldn't work for a 252 speed( minus some overlaps probably, but we still count them in a 27sp system) bike? What would be the effective range there?

I have both and occasionally feel tempted to put them together.

I think the Pinion weighs half a ton though.

Not as light as combining a Cambio Gear 16 speed front and a Rohloff 14 speed.

I have both and occasionally feel tempted to put them together

Please do, I would love to see that.