Gearbox & Belt Drive People
I like the whole concept of a gearbox bike. Tucking all the mechanicals inside an oil filled box makes real sense. I’m not convinced about the belt-drive though.
I think I’d like to see a real XC hardtail gearbox set up – so at least 20 gears and sub 13kgs. I haven’t come across one yet but I’d love to have a go when I do find one 😀Posted 5 years agoPePPeRSubscriber
Just as most car and van engines are going back to chains, bike manufacturers decide to start using belt drive!
I’ve been told that the reason cars and going back to chains is the Americans now have a 100,000 mile major service interval system in place, this has been the major reason belts have stopped being used as they can’t cope with this sort of distance.Posted 5 years agoswamp_boyMember
Car chains run inside a nice warm oily engine, always in line, a lot of them are duplex or multi row. Bike ones are out in the weather and crud and derailleur ones are out of line a lot of the time.
I don’t think you can compare bikes and cars directly, but it seems to me that belt drive has quite a few advantages for a bike, particularly in bad conditions, drawback is I don’t see how it could be made to work with derailleurs.Posted 5 years agoTracker1972Member
Hence the gearbox to do away with chainline issues. The idea of a bike that is essentially free of all minor maintenance is really appealing and not just for a commuter if the gearbox is in the bike rather than wheel. I like that for the longevity of components rather than weight distribution although weight in the middle may help the ride I guess.Posted 5 years ago
SRAM have internal gear hubs & the Hammerschmit so have the potential but they don’t seem too bothered
I suppose the cynical would say it’s not in their interests to product a long lasting maintenance free drive system when they can keep selling relatively flimsy consumable drive systemsPosted 5 years agomartymacSubscriber
its not cynical, its pure financial common sense.
imagine you are a shop keeper,
do you want to sell just one bicycle? or many?
i do think this A way forward, there are quite a few advantages, but id say that mass market acceptance is a long way off yet.Posted 5 years ago
the bikes look good though 😀jackthedogMember
I do wonder what gearbox R&D Shimano is sitting on while they remain in their comfort zone selling replacement chainrings and derailleurs. But I also wonder what the big guys like ZF might have sitting on a shelf/hard drive somewhere.
There are drivetrain manufacturers bigger than Shimano, and in the face of hybrid and electric drives becoming more prevalent under our vehicles, they may well have had little teams here and there spending the past few years looking into what future uses might still remain for their ‘gears in a box’ idea. Of course the bicycle market won’t be worth them bothering with for the moment, but in the not too distant future they might have a different outlook. Who knows.Posted 5 years ago
Gearboxes make sooo much sense and it’s good to see they’re gaining impetus.
However, belt drives really make no sense to me in this application:
– You need a specific length of belt to tailor for changes in chainstay length and gearing~ this would lead to a spares nightmare and would mean shops have to carry extensive stock, most of which would ultimately become dusty.
– There is no automatic centering or retention with a belt drive~ even with precision alignment and high tensions, there is always the possibility of derailment by a foreign object.
– There is no scope for trailside repairs if your belt snaps, so you’d have to carry a spare at all times, reducing any fancy weight savings.
So when it comes to Belt drive, I’m out!!
Despite all that, if they can replicate all the excellence of the gearbox design, without the unnecessary complications of the belt drive, with a patented proprietary standard with sufficient simplicity to be widely adopted within the industry, dragons den will lap em up… if I had a pretty penny, I’d happily invest in something of that nature.Posted 5 years agojackthedogMember
You need a specific length of belt to tailor for changes in chainstay length and gearing~ this would lead to a spares nightmare and would mean shops have to carry extensive stock, most of which would ultimately become dusty.
Ever been to a motor factors looking for a fan/alternator/power steering belt? Just the same thing. It’s not much worse than keeping a stock of various inner tubes in. In fact with the stupidly complicated ranges of tyres out there, keeping belts in stock is probably less of a PITA than being a Maxxis dealer.Posted 5 years agoveedubbaSubscriber
Nearly 3 years of commuting on a belt drive bike here. It’s fantastic: no oil to get on your clothes, no chain to have to clean every month (or week depending on the weather). It seems to go through a BB every 12 months, and I need to get a sprocket tool (like a chain whip) so I can get the thing off but it really is (almost) zero maintenance.
It’s never come off, not snapped, not done anything other than perform brilliantly. You do need to get the chainline right (shim the cog or buy a new BB), and I only have one gear (I have thought about putting a 2 or 3 speed hub out the back but don’t really need one).
Yes, you’d need specific belt lengths, but with sliding dropouts or an EBB there’d be less variation. Dunno how many Gates have in their inventory.
Derailment isn’t an issue – cogs and rings have holes in them to let mud and small stones out, so the likelihood is tiny, and probably less than that of a chain. Also, rings have a lip on the outside, and cogs on the inside, couple this with the centretrack system that’s now in place (that I don’t have incidentally) I’d imagine there’s very little chance of the belt coming off if it’s properly tensioned (which isn’t IME that difficult since I’ve never had to be more precise than using the “push the belt down tension deflection test”).
I reckon the biggest barrier to belts becoming widerspread is the lack of hubgear or grearbox options, and that (again, IMO) is down to the reluctance of larger manufacturers to make them as they’d lose a lot of aftermarket replacement parts business as someone’s already mentioned. Of course, fixing a hub gear is not as easy as a couple of mechs so there’d be more money-making potential there, but that’d be in the lap of LBSs to capitalise on.Posted 5 years ago
Good to hear some feedback veedubba~ you have 1st hand experience where I’m just spitting some internet conjecture; having thought about it a bit more, with the tensioning element, there doesn’t need to be that many lengths… for the most part chainstays vary by about 2 inches and ratios won’t vary that much.
There is still the hurdle of how it restricts design, due to the necessity of access to route the belt in the 1st place, but the output spindle of the gearbox would be compatible with chain or belt, so manufacturers could decide accordingly to fit in with their design.
The fact that regular cleaning and lubrication can be avoided can only be a good thing!!Posted 5 years agoMidlandTrailquestsGrahamMember
Gates have got a calculator on their site.
You can put in gear ratios or numbers of teeth and chainstay length and it will give the nearest belt drive option using available pulleys and belts.Posted 5 years ago
Bear in mind an EBB gives about 14mm of adjustment.MidlandTrailquestsGrahamMember
For example, I’ve got 50×28 with a 122t belt and 454mm chainstays.Posted 5 years ago
Putting those numbers in the calculator, I can see that 39×22 (113t) or 46×26 (118t) would give me slightly lower gearing or 55×30 (125t) or 46×25 (118t) would give me slightly higher gearing, all within the available EBB adjustment.
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