Belt drive. It may be time to admit defeat.

People talk about watts/kg when referring to road cyclists. I’ve heard it a few times (most in depth in Tyler hamilton’s book) that to win the TdF you need a power output of 6.5watts/kg body weight. He reckons the easiest way to achieve this is simply to lose weight.

Interestingly, and perhaps pertinent to molgrips/aracer’s discussion, two riders could have the same winning specific power output (6.5watts/kg) but if one was 80kg, they’d put more force through their bike/ drivetrain than a 70kg rider.

Does anyone know when the new 108 and 111 tooth Gates belts are coming out?
I want to get in the game but need a shorter belt. Come on Gates!

CBA to read most of pages 2 & 3… but, IME of belts (4 years and perhaps 4000km, so not up there with some of the distances discussed earlier) I’m on my second belt on a singlespeed commuter. It’s geared so that hills are a pain but the torque I’m putting through the drivetrain on steeper stuff must be quite high (and I don’t meant that I’m ace, just that in those situations, to move the bike along the rider needs to really get some leverage on the cranks).

I too have experienced the increased frequency of replacing BBs (perhaps one every 6-8 months).

My main reason for purchase was the low maintenance aspect. Apart from whole bike cleaning I never touch the belt in normal service – no oiling, degreasing or anything.

When the belt failed I actually thought my rear cog was stripping the splines off the freehub so I tested it by riding up a steep hill one evening and ended up stripping half the teeth off the belt. On inspection the remaining ones were worn to a triangular profile, and the creaking noise I thought was my freehub was actually the teeth shearing at their base.

I love my belt drive but I can see that in conditions where there’s debris getting into it, or where its being loaded from the side, then a belt would fail a lot more quickly than I’ve experienced.

Just to veer slightly OT (this is STW after all). One of the advantages of a belt is its lightness.

If we had a fully enclosed chain, how light could that be made? Maybe smaller pitch, etc. Didn’t Shimano have a crack at a 10mm pitch a few years back?

One of the advantages of a belt is its lightness.

That’s one of the things that first got me interested but now Gates have had to change the rear carrier to steel, they want you ideally to fit a snubber and you need a stiffer rear triangle that can be split which again adds weight. I’m not sure the weight savings are that great.

avdave2 – Member
That’s one of the things that first got me interested but now Gates have had to change the rear carrier to steel, they want you ideally to fit a snubber and you need a stiffer rear triangle that can be split which again adds weight. I’m not sure the weight savings are that great.

Good point. My experiments have all been on the ordinary belt and cogs. The stiffer rear triangle and split need not add more than a few grams of weight. If they do, it’s bad design.

However a rear cog made of steel is going to be considerably heavier than the same thing in aluminium and also than its equivalent for a chain. As for a snubber, that’s tantamount to admitting the system doesn’t work without a bodge… 🙂

A somewhat trivial point after all the heavy-hitting physics going on, someone earlier on mentioned the motorbike industry had given up on belt drive. Harley Davidson however didn’t and have it taped.

someone earlier on mentioned the motorbike industry had given up on belt drive. Harley Davidson however didn’t

BMW still use belts too.

Physics arguments aside, this is a very insightful thread. Thanks for sharing, OP.

wilko1999 – Member
A somewhat trivial point after all the heavy-hitting physics going on, someone earlier on mentioned the motorbike industry had given up on belt drive. Harley Davidson however didn’t and have it taped.

It was the thousands of miles I did on my HD in outback Queensland on dirt roads that convinced me belt drives were more than up to the job.

Is anyone else disappointed this thread is not about turntables?

epicyclo, I have thought of using bmx microdrive,and encasing it,might be doable with removable spider cranks.
would cost a fair bit tho.

emanuel – Member
epicyclo, I have thought of using bmx microdrive,and encasing it,might be doable with removable spider cranks.
would cost a fair bit tho.

But do it right and you’d never have to buy another chain or chainring for your drivetrain.

Well maybe “never” is a slight exaggeration – probably once every 50 years.

I don’t use a snubber and I’ve never had the belt ride up over the rear pulley. I really don’t know what the point of them is.
The rear pulley is steel, but then, so are the rear sprockets on my SS & Rohloff.

As we seem to going off on all sorts of tangents, here’s another one; Pinion Gearboxes.
If we are agreed that it’s rider power that is wrecking belts, then surely putting the reduction gears before the belt will increase the torque load or top run tension on the belt*. Has anyone got any long term experiences with a belt drive Pinion bike ?

*I’m a mechanic, not an engineer. I’ve probably used the wrong term, but you know what I mean.

MidlandTrailquestsGraham – Member
I don’t use a snubber and I’ve never had the belt ride up over the rear pulley. I really don’t know what the point of them is…

It’s really to compensate for lateral flex in the chainstays. On one bike I have, the chainstays are suitably stiff, so a snubber is not needed.

On another the chainstays are like noodles, and the only way to keep the belt on is by using a snubber. What is happening is that the teeth on the belt are arriving at the rear cog out of parallel because of the flex. The snubber forces them down. A snubber is a bodge IMO.

MTG you probably have just made the durability of the belts eureka moment in that obviously motorbike drives are from a gearbox! I would imagine by adding a pinion gearbox to the equation on a bike will enhance the lifespan of a gates drive on a bike as any torque applied through the belt is a lot more constant than direct pedal power.
I know the thread went off at a bit of a tangent but it’s actually all relevant to the durability of a gates belt drive set up.

we’re just exploring different paths to get the same answer.

epicyclo, I’ll have a go.

476km on the new belt and front pulley and it needs adjusting.
Don’t believe what Gates tell you about it being maintenance free.

I noticed it was getting a bit slack over the past few days.
I was going to adjust it yesterday, but after a very muddy ride home, the belt tension was OK again.
It hadn’t magically adjusted itself, it was the mud packed in between the belt and pulleys tightening everything up.
I jet washed it at work yesterday and it went back to being slack again.

Pictures showing the wear on the belt at less than 500km.

This is all very disappointing – I have been waiting to fit a Gates for a while now.

But thinking about it – why would you expect anything to be more durable than a steel chain?

I ran belt drive bike on my commuter for about a year. It creaked a bit under heavy load – I also snapped two belts within a year (covered by warranty but still)

It required constant tensioning despite the bike being a complete with belt drive and not a bodge.

I sold it and went back to a chain. No problems in 3 years…

clicky[/url]
weights, the splitter is 116g, an equivalent length of seatstay is 12g.

will write a few words, plus weight pics, later.

the other style of splitter, shown elsewhere in the thread, is the same weight as the dropout it replaces.

Further updates for those who are interested;
I entered Erlestoke 12 last Saturday on the belt drive Rohloff.
On my third lap, about 22km in, the belt came off.
It looked like the same problem I had at Sleepless In The Saddle when it was really muddy in the woods there, the belt and pulleys are pretty good at clearing wet or gritty mud, but leaf and twig fibres get trapped in the narrow slot of the Centre Track belt until it’s forced away from the pulley and jumps off.
I found a big puddle and did my best to wash the mud off and poke the fibres out with a pointy twig, finished the lap, then swapped to my single speed chain drive Lynskey.

I’m racing single speed at Bristol Bike Fest in two weeks time, so I fitted a SS rear wheel with a part worn steel pulley, a new SS belt and kept the same 50t front pulley with 700km wear on it.
With the bike updside down, I gave the cranks half a turn and noticed it didn’t sound quite right.
A closer look showed the sharp edges on the part worn rear pulley were cutting in to the belt.
You can see the difference between the damaged and undamaged parts as I stopped turning.

I don’t think it’s done any serious damage. I’ve swapped to another less worn rear pulley and it’s running smoothly now, although it does make me wonder what I’m going to do about a spare rear wheel for Bristol.

@ MTG – your patience and stubbornness(!) to continue with the system must be applauded.

I’ve been following your posts re belts for some time and remain “belt curious”.

The worry point for me is the frame stiffness seemingly required for the system to work effectively.

If I’ve missed you mention it apologies but is your ti frame particularly stiff?

The Skookum I have is nicely compliant at the back but this must equate to flex, which is bad for a belt drive – yes.

Keen to avoid needing a snubber.

It’s a mixture of sandy trails and claggy clay fields around here.

How have the belts faired with sandy use?

My belt is on a Kona A and due to the linkage pivots I initially had a massive problem with keeping the belt on due to lack of stiffness. Repeated slipping of the belt damaged it enough that it snapped, defeated by the sheer size of the Leicestershire Alps.
So, replaced it with a Centretrack belt and using the bolt in option on the Pro2 hub. Running it at “conventional chain” tension and I’ve had no problems since.
The belt came off once when my front wheel flicked up a massive branch which got caught in the chainstay but that would have pulled a chain off too (or snapped it, the chain that is)
Ridden on gloopy mud with no problems. At the moment its getting ridden weekly on Tentsmuir Forest which is on the beach so very sandy. Had the first issue of the dry dusty squeak that aflicts american riders the other day. Doubt it will be a problem tonight. …

I went for a Qoroz because they already made a belt drive expedition bike[/url] which has passed the Gates/Rohloff frame stiffness test.
Mine is a custom built cross between that bike and a their regular mountain bike[/url].

The one thing I really regret about all this is not keeping proper records of wear, both of chains & sprockets and belts & pulleys.
I’ve started being a bit more methodical about it all now, which is how I know the new front pulley has done 700km.
What I’ll do now is run belt drive till it’s worn out, then run chain drive until that’s worn out, so I can properly compare wear rates.

It’s very sandy round here, parts of Kinver Edge are literally like riding on a beach.
Normal mud, no matter how wet, sticky, sandy or deep, doesn’t seem to be a problem, the open design of the pulleys works well. It’s the leaf mould that clogs up the belt, where a metal chain would just chop through it.

http://revanchebikeco.wordpress.com/2014/05/31/the-weight-debate-chains-or-belts/

as you can see, the splitter adds 100g.

wow, admire your patience, but what a waste of time!

I have to say that all of this ois helping to convince me that gates belts are a faff and a waste of money.

I had toyed vaguely with the idea of a belt drive commuting fixie or SS road bike but I think I can live with the weight for the cost and apparent maintenance savings…

Shame really as I sort of want it to be the perfect SS drive solution, but the t ain’t really is it…

Emanuel, that’s a steel splitter. My frame is titanium and instead of a removable section with two lap joints, has only single lap joint, meaning I have to spring the two halves apart to create a gap for the belt, so I guess mine would be a bit lighter than that.

but what a waste of time!

You only know that from my experience.
When I bought in to this, there was no one else’s experience for me to go on, but it looked like a good idea, so I thought I’d try it.

There still isn’t much in the way of real world experience out there.
Gates have got lots of publicity shots of commuter bikes and the occasional mountain bike on a dry, dusty trail.
https://www.facebook.com/gatescarbondrive
STW have done their usual Copy & Paste of press releases without actually finding out if the product is fit for purpose or not.
http://singletrackworld.com/wp-content/uploads/2014/05/cavalerie-full-sussers-built-for-effigear-internal-gearboxes/
http://singletrackworld.com/wp-content/uploads/2014/02/nicolai-fat-pinion/

As far as I can tell, I am the only person in the whole world to have attempted to ride a Gates Carbon Drive through leafy mud and proved that it doesn’t work.

MTG

Serious question, have you sent pictures and mileage details to Gates to see if you can get their thoughts on the amount of wear you are suffering?

mtq-true, it’s what I had on hand: the difference in weight is for steel frames using that method.

I had one belt replaced FOC by Gates. I haven’t bothered chasing them about the others. Maybe I should have.

I’ll be at Bristol Bike Fest at the weekend if anyone wants to have a look at the belt drive. I’ve only ever seen two others in real life myself, both on display, not being ridden.

I do wonder whether companies might pay you for destruction testing of kit, Graham!

Orange had a belt + Alfine bike a good few years back. I wonder if the fact that they didn’t offer it as OE spec says that they also found it didn’t work so well on MTBs. There was certainly interest and some demand.

Personally I don’t see enough reason to even try it off road in the long-term (not meant as a dismissive view of your experience and these posts MTG, quite the opposite, if I had more time I’d like to know from experience not just building some city bikes – so this thread is appreciated), mainly as benefits over a chain were almost non-existent. For someone like me who changes ratios and wheels etc fairly regularly it would prove more faff than I could live with. Great for a clean city bike, but so is a chain-guard and wax lube : )

You only know that from my experience

not entirely. Look at the history of bicycles and look at how much has changed in drive-train technology, and every single “advance” be that belt, gearbox, shaft, 2WD, whatever has failed the remove the chain and sprocket as the lightest, most versatile, most long lived, most robust, and most cost effective way of propelling a bicycle forward short of strapping a motor into the frame.

Could have told you that from the get-go. But I don’t need to, you’ve just found out for yourself 😀

Latest news;
I stripped a load of teeth off the belt last night “just riding along”.
I’m a bit behind with uploading my rides, I’m adding the last month or so now. I’ll report back when I’ve finished, but I reckon the belt lasted less than 3000km

3098km

I hate all these “It doesn’t work threads / pictures” as I built up a bike specifically for running belt but is still running a chain as I can’t decide whether to try it out or not.

I do like the idea of having a truly hosepipe clean bike with no oily drive train to pick up gunk…… and Gates have finally produced the 111T belt I would need to make it all work.

My set up includes an Alfine – do you think I would get better mileage by having gears (i.e. putting less power through the belt)?

I believe MTG has also destroyed all the same bits while running a Rohloff so I think the answer is no – it is unfortunately crap for off road use however you set it up.
I’m also very disappointed as I’d also had ideas of running one with my Rohloff rigid bike for even less maintenance and a little weight saving. The weight saving though went out of the widow when gates were forced to move to steel carriers. Now it looks like the maintenance is a non starter too.

I’d replace with a traditional chain/sprocket/chainring set up.

The money you save on not buying replacement belts you can put towards the jacket fund to get something less pish than those you had highlighted.

😉

Ndthornton, that one above is on a Rohloff, so no, it doesn’t seem to make a difference.
I’m still not convinced one way or the other about the cost of belt over chain.
I’ve just fitted almost new second hand chainring, sprocket and chain, so I’ll log the miles on that and see how long it all lasts.

It’s not just the cost though, it’s the sudden catastrophic failure.
Apart from the one with the stone punched through, which lasted a few weeks with a hole in it before breaking, they have all failed without warning.