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_Ferret_
Joined: 25 Mar 2008
Posts: 460
Location: Freiburg, Germany
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Daz555
Joined: 11 Aug 2008
Posts: 1272
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 Posted Thu Nov 5, 2009 2:22 pm |
Belts are proven on motorcycles so I'd say belts might be the way to go if the derailleur finally comes to extinction. Plenty of motorcycles have them these days and the lifespan is far greater than a chain setup. Shaft-drive would be great if they can get the efficiency/weight/strength balance right.
So for me the ultimate solution would be shaft-drive with internal gearing be it hub or some other gearbox, followed by the same solution but with belt-drive.
As I said though - weight and efficiency are key and compromise will always be the order of the day. Having said that I could happily live with a bit more weight and a bit more effort for an almost maintenance free and almost unbreakable drive solution.
You only need two tools: WD40 and Duck Tape.
If it doesn't move and should, use the WD40.
If it shouldn't move and does, use the tape. |
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yeehaamcgee
Joined: 07 May 2007
Posts: 6057
Location: Worth Nails
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Posted Thu Nov 5, 2009 2:35 pm |
Dazz, that's bullcrap. If belts and shafts are superior, in any way at all, then why do all properly high performance racing bikes still use chaindrives?
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
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daniel_owen_uk
Joined: 21 Feb 2007
Posts: 134
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Posted Thu Nov 5, 2009 3:08 pm |
Because chains are more efficient!
Surely that's not the only consideration here? Formula 1 cars don't have disk changers and air con, but that doesn't mean they aren't good for the car you drive every day.
Why does everyone talk about ultra high end equipment as a reason not to use belt drives?
It's almost non sensical.
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yeehaamcgee
Joined: 07 May 2007
Posts: 6057
Location: Worth Nails
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Posted Thu Nov 5, 2009 3:21 pm |
F1 cars do, however, have disc brakes and independant suspension - things that we know are great for everyday cars.
If a chain is so good that they are yet to be superseeded even on world superbikes, and MotoGP, and Motocross, why do you think a belt-drive is better?
If they were better, then those designing and building race bikes WOULD be using them.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
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.blitz
Joined: 02 Sep 2008
Posts: 2016
Location: Dick Slee's Cave
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Posted Thu Nov 5, 2009 3:41 pm |
A clean chain is over 98% efficient. No other transmission system (gears, belts, shafts) gets anywhere near that and it's a very important consideration when designing a bicycle.
I've owned three belt-drive motorcycles and for street use they are definitely the way forward. Unfortunately motorcycling can be very fashion-conscious and until the MotoGP boys start using them (unlikely when every horsepower counts/gearing changes/variable-length swingarms etc)) we won't see too many on the road.
| Daz555 wrote: | | Belts are proven on motorcycles so I'd say belts might be the way to go if the derailleur finally comes to extinction. |
They only work when they are properly tensioned - any deviation from 'feckin tight' will cause them to jump teeth or derail. Belts are also very vulnerable to debris between the teeth on the belt and the recesses in the 'sprockets' - not exactly off-road friendly.
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Daz555
Joined: 11 Aug 2008
Posts: 1272
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Posted Thu Nov 5, 2009 4:24 pm |
| yeehaamcgee wrote: | | Dazz, that's bullcrap. If belts and shafts are superior, in any way at all, then why do all properly high performance racing bikes still use chaindrives? |
Err, for high performance at the bleeding edge of sport.
...and did I say they were superior? Nope. I just said that I'd like to see the tech used on derailleur free mountain bikes.
You only need two tools: WD40 and Duck Tape.
If it doesn't move and should, use the WD40.
If it shouldn't move and does, use the tape. |
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yeehaamcgee
Joined: 07 May 2007
Posts: 6057
Location: Worth Nails
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Posted Thu Nov 5, 2009 5:02 pm |
but why, is what I'm saying. If they had any advantage, then they WOULD be getting used on machines where performance is everything.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
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rhyko7
Joined: 03 Nov 2008
Posts: 450
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lastwords
Joined: 19 Sep 2008
Posts: 124
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Posted Thu Nov 5, 2009 7:01 pm |
| _Ferret_ wrote: | That's the problem. No-one has yet proved that belts are better than chains and since chains are easier and cheaper to produce we'll probably have them for a while yet.
I still like the concept of an alternative to a chain.
Belts generally can take an angled line better than chains - think about the links and pins and general moving parts in a chain compared to a belt that is one constant material. There are more points at which a chain can break, each time you have an intersection of different materials in a structure there is a weak point and one of these after time and under strain can break - ever heard of the weakest link... 
Maybe they'll be something better, maybe not even a belt... |
The type of belts that i have seen used on bikes so far (tooth flat belts) do not run at angles i am a mechanical engineer working with presses which use a lot of these types of belts, i can say that the pulleys (alluminium) they run on dont last all that long, bearing in mind they are usually in a far cleaner enviroment than a mountain bike.
They also require a fair bit of tension to ensure the teeth dont slip so the only way you would get gears is with a hub gear or somthing along them lines.
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yeehaamcgee
Joined: 07 May 2007
Posts: 6057
Location: Worth Nails
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Posted Thu Nov 5, 2009 7:02 pm |
but of course with hub gears, all (well, almost all) current suspension designs have to be scrapped.
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_Ferret_
Joined: 25 Mar 2008
Posts: 460
Location: Freiburg, Germany
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Northwind
Joined: 06 Sep 2008
Posts: 4590
Location: Edinburgh
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Posted Thu Nov 5, 2009 8:44 pm |
| cee wrote: | belts are not really indestructible...think about the belts in a car engine....they can stretch/split get teeth wear, and need replaced when they have not really snapped....
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That's certainly true, but then the replacement schedule on a cambelt is usually tens of thousands of miles or several years, running at several thousand rpm for hours at a time. Don't know about you, but my cadence is a little slower
| yeehaamcgee wrote: | | but why, is what I'm saying. If they had any advantage, then they WOULD be getting used on machines where performance is everything. |
High-silica tyres give a huge advantage for road motorbikes, but nobody uses them on the track... Same goes for heated grips, comfy saddles, top boxes and big screens  Why do all racers wear leather? If goretex is so good they'd be wearing that, right
| yeehaamcgee wrote: | why would a belt take an angled line any better than a chain?
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A narrow belt does, like the v-belt in my lathe's gearbox, it'll deal with a huge deflection, something like 4 or 5 times what you see in a bike driveline But a wide belt like bikes would use probably would deal worse, not better, with deflection. I think this probably confuses people a bit.
We still do it because we're forever chasing what we've already found |
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sheepsteeth
Joined: 07 Mar 2007
Posts: 5472
Location: kent
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Posted Thu Nov 5, 2009 8:58 pm |
im pretty sure chains are stronger than belts. Engines with chain driven camshafts have longer service intervals than belts.
The replacement of the chain drive for bikes is a nice idea as an experiment but it is trying to solve problems which dont exist. the whole belt drive idea is an attempt to try summat new and im sure i saw the idea on an orange p7 a couple of yrs ago and was designed for single speed. of course its good to try new things, but some ideas are plain sh1t regardless of who came up with them.
If any thing was going to be improved i would say cables need improving so they dont stretch (especially if you run shimano) for longer servicing interval. lower friction, better sealed outers (im thinking some kind of micro assembly similar to the way a dogs ars* works when it parks its brekkie, a super supple sleeve which is bonded to the cable and can pass inside the main outer cable)
1, 2, 3, crush, |
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joshtp/mbukman
Joined: 15 May 2008
Posts: 884
Location: the place you drive 4 hours to, WALES! Swansea
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Posted Thu Nov 5, 2009 9:20 pm |
belts might not provide any real advantage, but we need new things to progress the indudtry, for incetance, when sus forks were first introduced they had 10mm of travel, flexed like noodles, had very little damping, and did very little good, and im sure people said "sus forks are no good, our rigids do fine" but people persisted and slowly people started to believe in them, now look at us, we all strugle to cope with the idea of a rigid bike, very, very few of us ride a bike that has no sus.
"oh dear, i seem to have hit a tree."
GT Aggressor XCR 09 + shiny bits |
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sheepsteeth
Joined: 07 Mar 2007
Posts: 5472
Location: kent
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Posted Thu Nov 5, 2009 9:27 pm |
somethings have met their natural evolution though, the chain drive on a bike is light, efficient, tough, quiet and not too pricey. I dont see where it can be improved apart from the cables.
Striving for perfection is an outstanding human trait and what puts us at the top of the food chain. but sometimes people are trying to fix problems which dont exist.
1, 2, 3, crush, |
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Northwind
Joined: 06 Sep 2008
Posts: 4590
Location: Edinburgh
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Posted Thu Nov 5, 2009 9:34 pm |
I'd like to see some more alternatives. Gear drive... A wee row of little cogs all along the stay, just waiting to eat your trousers. Or hydraulic drive like on the front-wheel-drive dirt bikes. That'd be awesome. Or electric transmission, you pedal a dynamo to power a motor, and use the chainstays as the conductors.
We still do it because we're forever chasing what we've already found |
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yeehaamcgee
Joined: 07 May 2007
Posts: 6057
Location: Worth Nails
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Posted Fri Nov 6, 2009 11:14 am |
| Northwind wrote: | | cee wrote: | belts are not really indestructible...think about the belts in a car engine....they can stretch/split get teeth wear, and need replaced when they have not really snapped....
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That's certainly true, but then the replacement schedule on a cambelt is usually tens of thousands of miles or several years, running at several thousand rpm for hours at a time. Don't know about you, but my cadence is a little slower |
I had a chain driven camshaft on an old Mazda. It had no replacement schedule. The reason for that is, they never broke.
High-silica tyres offer better lifetime, but less grip, so they're not used (much) in motorsports.
Leathers offer more protection when crashing than goretex. Lots of bikers still wear leathers.
Heated grips? I've know several bikers who detest them, it actually makes their hands feel even colder, because their palms are all nice and warm it feels as though the rest of their hands are blocks of ice.
What I'm saying is that there is no performance advantage to belts. You're swinging this into a fit-for-purpose argument.
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cee
Joined: 16 Jul 2007
Posts: 2531
Location: Edinburgh
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Northwind
Joined: 06 Sep 2008
Posts: 4590
Location: Edinburgh
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Posted Sat Nov 7, 2009 2:50 am |
| yeehaamcgee wrote: | | What I'm saying is that there is no performance advantage to belts. You're swinging this into a fit-for-purpose argument. |
No I'm not... You're trying to define performance in too narrow a manner, or too simple maybe- "performance" isn't a sliding scale from 0 to 10, it takes in many different factors and things can perform in one field but not another. So frinstance:
| yeehaamcgee wrote: | High-silica tyres offer better lifetime, but less grip, so they're not used (much) in motorsports.
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The other advantage of high silica tyres is better grip when cold, and better grip when wet. . They have less performance in terms of traction but that's not all that matters- if maximum traction isn't your main concern then a super-sticky tyre is no longer high performance, in fact it'll be a very poor performer on a winter commute.
We still do it because we're forever chasing what we've already found |
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