Hydraulic gears, why not? « Singletrack Forum

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Hydraulic gears, why not?

61 posts & 23 voices | Started 1 year ago by spindi | Latest reply from spindi

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spindi - Member

I recently spotted that Campagnolo are due to release some electric gears. Shimano have done in the past. Strikes me as another faff to get in the way of a good session on the bike? I know that's a very personal opinion but I don't want to reach for my bike after having forgotten to charge the gear system.

Anyway, the thought occurred to me - why hasn't anyone gone the hydraulic route (with a specifically designed derailleur)? Yeah, there is a bit more maintenance but cables aren't perfect either. Lots of frames (specifically many UK based) with full outers could use them straight away.

Maybe I should just go and buy a Rohloff and have done with it. I hate derailleurs / cables.

Posted 1 year ago #
bristolbiker - Member

Have you tired Di2, or seen that custom brain 're-map' that was on here the other day for MTB 1x10??!? It is the future I tells ya...... (apart from the cost, obviously

FWIW, IIRC, battery life was several months even if you rode several hours a day and changed gear like an epilectic gibbon....

The ultimate minmum faff setup may be an electric shifting hub gear - Di2 meet Alfine 11 after a visit to Weight Watchers <rubs legs Vic Reeves style>

Posted 1 year ago #
cynic-al - Member

Agreed, cable stretch would be a thing of the past

Someone made a cable ->hydraulic converter for brakes years ago IIRC.

Posted 1 year ago #
ac282 - Member

Someone already makes them. V expensive.
http://www.5rot.com/preise.html

the Di2 stuff that Fairwheel have done looks like the future to me.

Posted 1 year ago #
scaredypants - Member

wouldn't you need 2 circuits, pushing opposite ways ?
sounds a bit unwieldy

Posted 1 year ago #
roadie_in_denial - Member

Ah...this one again. As I recall Shimano once had a system called AirLines, which was, unsurprisingly, a pneumatic system.

Posted 1 year ago #
TandemJeremy - Member

solution in search of a problem. Cables work. Hydraulics - you would need some way of dealing with fluid expansion in heat, much more complex (thus heavy)and expensive, no advantages

Simplify then add lightness

Posted 1 year ago #
bristolbiker - Member

much more complex (thus heavy)and expensive

I won't argue about the complex and expensive, but for a price you can have light and perdy.... see ac282's link. Very nice.

Posted 1 year ago #
scaredypants - Member

Hydraulics - you would need some way of dealing with fluid expansion in heat

not if 2 opposing circuits ?
minimal heat increases surely, unlike brakes ?

Posted 1 year ago #
simonfbarnes - Member

double pipe run

also the hydraulic part would have to be a cartridge that plugged into the mech body as they wear out so fast...

Posted 1 year ago #
TandemJeremy - Member

scaredypants - ambient temperatures. You would need a closed system ( not open like brakes) then you need some way of compensating for ambient heat - otherwise as the temp outside changes the gears go out of adjustment / lock up depending on design. as hoses contract and expand as temp changes then the internal volume changes and fluid expanmds and contracts withheat as well.

Bristol biker - hydro gears must be heavier that cable - far greater complexity = more parts - more weight. You needs a master cylinder, slave cylinder, full lenghth hoses, expansion device - must be more than a lever a cable and a projection on the mech

Posted 1 year ago #
bigyinn - Member

TJ Simplify then add lightness

Have you been reading that article about Gordon Murray in Evo mag this month?

Posted 1 year ago #
scaredypants - Member

scaredypants - ambient temperatures. You would need a closed system ( not open like brakes) then you need some way of compensating for ambient heat - otherwise as the temp outside changes the gears go out of adjustment / lock up depending on design. as hoses contract and expand as temp changes then the internal volume changes and fluid expanmds and contracts withheat as well

closed system, 2 opposing (and effectively symmetrical) circuits. As long as it doesn't explode, what's going to go out of adjustment ?

Posted 1 year ago #
TandemJeremy - Member

who / what? Thats a quote from Colin Chapman of lotus

Posted 1 year ago #
spindi - Member

solution in search of a problem. Cables work

Er, not in winter which is upon us. If you want them to work all the time and work well then you have to faff quite a bit or spend £££ on some Gore ones. They stretch, they corrode etc etc.

Contrast this with my disc brakes. Bought, put on bike. Job done. Also, heat expansion er, what? How often do you change your gears? Your derailleurs aren't going to be beside a big rotating disc with some maybe sintered pads pressing on it.

The Rot5 stuff I have seen before. They are beautiful but seeing as they are a very small company the price will always stay the same sadly. It would be great if it only took one cable too even if this meant a barrel adjuster (just like a cable or disc braking system) to account for atmospherics.

Posted 1 year ago #
njee20 - Member

That 5rot system is suspiciously light, they must be missing out fluid/hose I reckon, which is where you'd add weight over a mechanical set up.

Electronic is more likely to be the future I reckon.

Posted 1 year ago #
spindi - Member

Ah...this one again. As I recall Shimano once had a system called AirLines, which was, unsurprisingly, a pneumatic system.

Doomed from the start. Air compresses obviously. Dot fluid etc doesn't to a large extent.

Posted 1 year ago #
bristolbiker - Member

Bristol biker - hydro gears must be heavier that cable - far greater complexity = more parts - more weight. You needs a master cylinder, slave cylinder, full lenghth hoses, expansion device - must be more than a lever a cable and a projection on the mech

But it's not comparing apples-with-apples - yes you add a mater cylinder and a double run of pipe.... but you take out all the ratchet mechanism at the shifter and the return spring gubbins at the mech.

This was an argument used at the dawn of hydro brakes and the like-for-like weights are now comparible (but I accept not identical).

It's a moot point - Di2 will win, cause it solves some problems with mechnical systems (self aligning etc) and, more importantly, cause Shimano says so!

Posted 1 year ago #
jim - Member

Er, not in winter which is upon us. If you want them to work all the time and work well this is then you have to faff quite a bit or spend £££ on some Gore ones. They stretch, they corrode etc etc.

Full runs of XTR inner and outer have done neither for me.

Posted 1 year ago #
spindi - Member

Ah...this one again. As I recall Shimano once had a system called AirLines, which was, unsurprisingly, a pneumatic system.

I could live with the weight if it worked all the time with minimal maintenance. Last year I messed with my brakes for approximately 40 minutes and that was the time that it took me to bleed both of them (and shorten one of the hoses). Compare and contrast this with the gears

Posted 1 year ago #
TandemJeremy - Member

in that case it would lock up as the ambient temp changes surely. The TESI bimota motorcycle had hydro steering in one incarnation in exactly the manner described and they found this to be an issue.

Unless the volume in the hoses and the volume of the fluid expanded and contracted by the same amount as ambient temp changes you would get volume changes which would create pressure differentials which cause the seals to distort and lock teh system. single hose with spring return it would go out of adjustment.

Think about the old closed brake systems where lever feel / bite point altered as temps changed - it would be a much smaller effect but you would need some way of compensating for this.

Teh

Posted 1 year ago #
jimster - Member

Lets hope Avid / SRAM don't go down this route.

Posted 1 year ago #
spindi - Member

Full runs of XTR inner and outer have done neither for me.

How much? Probably £40 worth of cabling or something like that? Hydro hose isn't much more expensive.

Posted 1 year ago #
TandemJeremy - Member

I do find it strange the problems folk have with cables. I lube mine occasionally and that is it. Work fine summer and winter for years with very little faff. Using basic cables and GT 85 / grease to lube

Posted 1 year ago #
cynic-al - Member

None of you are considering the option of having the indexing system separate to the hydraulics (which was of course how airlines worked )

I think it would be good to get it looked into, along with beefier mech pivots that last. Shimano seem to be pretty good at making clever durable stuff, light and cheap.

Posted 1 year ago #
simonfbarnes - Member

but you take out all the ratchet mechanism at the shifter and the return spring gubbins at the mech.

in favour of hydraulics you could use a tapered shuttle to meter the exact amount of fluid to move the mech the right distance for each change - I imagine linear pull is approximate, but the ratchet and spring are not much weight compared to a whole extra pipe run...

Posted 1 year ago #
spindi - Member

The TESI bimota motorcycle had hydro steering in one incarnation

Now, that's just stupid. Surely if the ambient temp changed so much it would only result in a misshift? Or no shift? Hardly cause for concern if there was a way to mechanically dial it in (as per a disc brake like lets say the C2 from Hope).

Posted 1 year ago #
jim - Member

How much? Probably £40 worth of cabling or something like that?

Outer is £22 for 10m. Or gear cable set is £18.

How much more expensive would hydraulic mechs and shifters be?

Posted 1 year ago #
_tom_ - Member

Gears are enough of a faff already, why add to the pain?

Posted 1 year ago #
njee20 - Member

But then what does it achieve? If you have to constantly 'mechanically' adjust your hydraulic discs!

XTRi2 FTW!

Posted 1 year ago #
TandemJeremy - Member

Three principles to remeber.

KISS
Simplify and add lightness
Cheap / light / strong - pick 2

Posted 1 year ago #
spindi - Member

How much more expensive would hydraulic mechs and shifters be?

You're talking connections. I.e. cable. Not the item itself. £4 a metre here.

A SRAM X0 derailleur can cost £169. Then the RH shifter would be around the £75 mark. Surely hydro alternatives could be manufactured with profit for the same money. They could be far simpler at the mech (the dangly bit that gets whipped off by rocks and branches) and more complex at the shifter.

Posted 1 year ago #
bristolbiker - Member

in favour of hydraulics you could use a tapered shuttle to meter the exact amount of fluid to move the mech the right distance for each change - I imagine linear pull is approximate, but the ratchet and spring are not much weight compared to a whole extra pipe run...

Again, a moot point - I'm sure it at comparable weight at a cost, but that cost would be mental. Speaking of mental costs, the Rot5 setup appears to be using reltively thin plastic hose. I have no idea what the comparable weight per m of two runs of that full of fluid is compared to a steel reinforced brake cable outer with a steel cable in it.

Posted 1 year ago #
nickc - Member

I'm with TJ. I set up my gears maybe once a year when I change the cables. Never have to touch them after that. Reckon shaman will release a Di2 version of XTR in next couple of years

Posted 1 year ago #
simonfbarnes - Member

Three principles to remeber.

KISS
Simplify and add lightness
Cheap / light / strong - pick 2

there's considerable redundancy there... perhaps you should apply the first to the rest ?

Posted 1 year ago #