Derailleurs...what do you look for in yours?

rhyko7

i broke another rear mech today- Shimano Alivio gave up the ghost and started tring to follow the chain around the cassette! :roll:

NatoED

get a Sora rear mech they are £25 and much stronger than Deore

supersonic

They don't work with all capacities and some large rear cogs though.

_Ferret_

I've broken plenty of chains. I like the idea of a belt but I would be interested as to how you fit them.

I still think it is only a good idea for singlespeeds at the moment. Someone needs to come up with a good idea for a normal mountain bike.

switchback18

Main thing for me with most components is how long they last - I have an XTR that I've used for about 4 or 5 years, riding a lot, and it was about £25 second hand off ebay, looked like it had been used for a couple or 3 years already. So quality for me is the main thing, but at a realistic price...

rhyko7

NatoED wrote:

get a Sora rear mech they are £25 and much stronger than Deore

its ok i had a spare LX mech (with stretched spring) ghost shifts a bit and doesnt change down very well but it will do for now, i managed to get it on, put chain back together and go back out riding, so wasnt complete disaster. like guy above did ile try find a good one on ebay rather than forking out for a new one that i may end up snapping on a rock.

Anonymous

I honestly look for how sexxy it is, small dérailleurs are sexxy to me

switchback18

RichardJiles wrote:

I honestly look for how sexxy it is, small dérailleurs are sexxy to me

Along the lines of rhyko7's sig, I worry about people who see mechanical things in this way..!

tom_goggin

@ larmafarma

yer im doing the whole system, 2 shifters plus front and rear derailleur, so plenty of work to be getting with! where did u do that course?

colintrav

tom_goggin wrote:

Im doing a university project looking into re-designing the current derailleur/shifter system to combat problems such as weathering/corrosion and the amount of maintenence required to keep shifting crisp. I know the idea other topics have discussed potential re-designs of gear shifting mechanisms, but what I really wan to know is...what do you want from your shifter/derailleur? Any comments are appreciated, thanks in advance!

Build quality , VFM , longlivity

cee

for me...the hub gear alla Rohloff Speed Hub...is getting closer to the perfect solution for me. and i say closer carefully because there are some showstoppers....

the boos....
twist shift...uses 2 cables (1 for up 1 for down) because it is not sprung like a mech there is no mechanical memory involved..
Cost...nuff said

the yays...
no mech to smash off a rock (again....)
little or no maintenance other than a flush and oil change..
14 distinct gears is all we really have anyway (or close enough)

If they could get a proper shifter and half the cost, i would seriously consider it.

joshtp

supersonic wrote:

How do you fit a new one?

split seatstay

ride_whenever

According to the fat cyclist (admittedly using in the dry) there is basically no difference in the feel of chain vs. belt. As for the load breaking of chains, most people either have, or know someone whos broken one, usually due to a poor rivet. With the complete build there is no issue with that.

Anonymous

Crap manufacturing is the reason most chains break. Ignoring manufacturing faults, their strength is far in excess of any forces we put through them

_Ferret_

yeehaamcgee wrote:

Crap manufacturing is the reason most chains break. Ignoring manufacturing faults, their strength is far in excess of any forces we put through them

Obviously if you had a prefect chain then this would be true. But all chains are made with links and pins and these have tolerances and give over time due to shifting gears etc. A belt drive should theoretically last longer because it has no links to stretch over time, regardless of which gear you are in the belt would be able to take the angle it has to run at better than a chain.

Has anyone tried a belt drive with more than one gear?
I'd be interested to know if it can take gears (frinstance largest cog to largest cog) without twisting...

cee

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....

I thought the only way to run gears with a belt drive was to use a hub gear system?
could be wrong.

Anonymous

why would a belt take an angled line any better than a chain?
These are all assumptions/wishfull thinking, I see no concrete "this is why belts ARE better" statements.

_Ferret_

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...

Anonymous

belts can break as well though.

_Ferret_

of coarse - plus I'd still like to know how you would change one.

It's just too open at the moment - belts are yet to be proven. Chains work and if correctly fitted they work well for a long time...

Daz555

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.

Anonymous

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?

daniel_owen_uk

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.

Anonymous

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.

.blitz

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.

Daz555

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.

Anonymous

but why, is what I'm saying. If they had any advantage, then they WOULD be getting used on machines where performance is everything.

rhyko7

arent BMW's chain driven?

lastwords

_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.

Anonymous

but of course with hub gears, all (well, almost all) current suspension designs have to be scrapped.