Hydraulic Shifting for MTB

molgrips – Member
I’ve already designed the automatic. It uses one of those infinitely variable hub gears that someone’s invented (something to do with ball bearings inside) and a torque sensor to keep the pedalling speed within a user-defined range.

Hmmm, I thought about that infinitely variable gears too. They used to have them on very old motorbikes when they still used some weird belt with a massive rim on the back wheel. Bit surprised the whole idea never caught on more with bikes; then again… 🙂

Scooters have variable gearing in a similar manner to the DAF – its very simple as its a pure mechanical system and could be adapted to MTBs

Electronic is the way forward for shifting, not hydro.

You can put electronic shifters anywhere, have more than one button for shifts, battery life is months, the system is lightweight, easy to install/adjust and reliable.

The next big thing will be electronically adjustable shocks, oil that changes viscosity when an electric current is put through it. Cannondale have already used electronic lockouts. Easy one push buttons, no force needed to move a sticky cable via a shifter unit.

Proflex tried the piezo shock thing as well. Had wheelie bins out back full of knackered shocks.

ok Crotchrocket as the example you have given is B****ks i will be fuller.

I said price comparison

wiggle list an Alfine 11 at £430 and list the shifter at £65, so that is £495 for a hub, two derailleurs, two chainrings, two shifters and a cassette. I trust that makes sense?

Road.cc have an article where they claimed to have weighed the hub and sundries and come to 1744grams, they do mention that Shimano are claiming 1590grams

Now for £500 i can get some fairly high-end kit i think you would agree.

According to wiggle.

XT front mech £35, rear mech £70, Cassette £65, Shifters £100, and the rear hub is £45 Chainrings, as you would be using the middle with the alfine i feel the correct balance is struck by quoting the inner and outer only. So XT inner £15 and outer £80 that comes to a grand total of £410. So i still have £90 to spend.

i could get a far lighter hub than the XT and still be within budget, a few ti and alu bolts. XT chainrings are obscenely expensive TA or Middleburn would be alot cheaper and would let me stretch the budget further.

Now for weight, According to the weights published by Shimano, Front derailleur is 152g, rear 227, cassette 256, shifters 255 and rear hub 411grams. i can’t find a chainring weight quoted, but that lot comes in at 1301grams. for arguments sake i will assume two chainrings are around 100grama so yes quoted v actual but still 300grams lighter. and if we look at quote v quote then 200 grams lighter.

So to summarize you can save £90 and save more than 200grams in weight by running an XT drivechain as compared to an Alfine 11.

As i said earlier look at the price and the weight and then make a comparison on that.

and further, i decided to read a bit more of that thread and someone else comes along and says the bikes they converted from derailleurs to Hub gears gained between 200 and 300grams. Which ties in to what i just said.

If you want to use hub gears fine, do so, but they are at this time heavier and less efficient than derailleurs.

CBA 🙄

You asked for evidence i have given you the evidence, it is even in the thread you quoted to me. Hub gears are heavier at a price point and that is what i said earlier.

Had a look on the Madison site and Alfine 8 and shifter is around £250. and a bikemagic article is quoting a weight of 1590grams, so what can i buy for that, bearing in mind the gear range can be replicated with a single ring up front.

For me the issue with hub gears is not the weight, but the weight distribution. Esp on FS, less of a problem on HT.

One day I’ll have a belt drive hub geared bike 🙂

I would be interested in finding out more about the drag issues on hub gears. Anyone heard anything about dyno tests on the alfine compared to conventional set-ups?

There’s a load of info about it somewhere online with Rohloff.

Found this on their website. http://www.rohloff.de/en/technology/efficiency/ I need to look over it when I’m a bit more sober though. Their conclusion seems to be that more research is needed but there’s definitely some interesting stuff in there.

Another question, any tests been done into how long hub gears last compared to derailleurs?

Another question, any tests been done into how long hub gears last compared to derailleurs?

Wasn’t one of the round the world cyclists a year or so back using a Rohloff? I don’t doubt that a well designed hub gear will last a while, but then again a derailleur will last a while as well.

I do wonder what the average mileage of mtbers is though, it is all well and good saying a hub or mech will last, for arguments sake, 20,000 miles, but if the average rider is doing 2000 per year will they really keep the bike for 10 years so that the part has worn out?

The weight and weight distribution issue may be partially solvable by relocating the hub gear to the bottom bracket, quite how i am not sure and I don’t know how much this would help with drag, but it would take a major collaboration between Shimano/Sram and Trek/Specialized/etc to get it into the marketplace. I don’t think it can be done cost effectively by any niche player. Your going to need a lot of redesigning of frames to accomodate such a move.

There was a link on the Thorn forum to an article on the British Human Power Club website[/url] with some very good research on the drag of hub and derailleur gears.
The link’s dead now and nothing comes up with a search for Rohloff on BHPC.
From what I remember, there wasn’t a great deal of difference, although I think it depended partly on which gear the Rohloff was in. 11th is direct drive and has the least drag.

With regards to hub gears etc, I refer to a learned fellow on this very forum:
Stu McGroos lets put this alfine weight issue to bed once and for all thread

Seemed to make things pretty clear…

ex-pat, and if i also refer you to that thread, a bit further down the page, it states the hub weighs more. What you also need to consider is what was being upgraded from and to in the original post. It was not like for like.

As i said earlier, you should compare price and weight wise, i am sure that a hub gear could be lighter than some derailleur combos, but wuld comparing £500 of hub with £50 or derailleurs be fair? I think not.

It’s not quite that simple though, is it ?
My Rohloff uses one chainring and one sprocket and has very little in the way of external vulnerable components.
Add up the extra cost of replacing three chainrings and a cassette, plus the occasional bent hanger or broken rear derailleur and, over the life of a bike, the price gap narrows.

bluetooth would seem the be the way forward especially now they are working on transmitting power through it too….would mean no wires/cables, infinitely tuneable by pc and easy swapping of bits through pairing

i was thinking earlier how little we as a species have advanced in the last 20 years…..in the 60s we we went from being earth dwellers to landing on the moon….now all anyone cares about is stopping a bit of ice melting! same seems to apply for the bike industry….but thats mostly down to the uci who still think it is the 60’s

I read ages ago an article about derailleur efficiency. It reckoned a chain was 98% efficient with a straight chain line but that dropped to 85% or something at acute chain lines, even the ones that you might actually ride.

It’d probably be worse still when your lube wears off and gets replaced by grit and mud.

i was thinking earlier how little we as a species have advanced in the last 20 years

Lol. As you sit here debating an inconsequential subject with hundreds of people all over the country, probably whilst doing something else like working, on a machine that surpasses any 60s engineer’s wildest fantasties by a factor of a million on a network that links almost the whole world together..

Irony?

He said “as a species” not our technology

Yes, he said species then went on to talk about technology.

I don’t think a species can be expected to advance much in less than a generation.
I would take it to mean human technology rather than humans themselves.

On efficiency if you read the rohloff article it mentions that the efficiency drops depending on ratio.

I can’t see a Rohloff being less efficient than a derailleur caked in the Peak District’s finest clay?

11th is direct drive and has the least drag.

ie zero as it’s direct 1:1 drive 🙂 My simplistic efficiency check was to ride up the steepest hill I could only to find the gearbox casing still at ambient temperature. Any significant friction would have warmed it up at least a little. However, as copiously documented by me previously, the Rohloff cannot tolerate even minor immersion which makes it a non starter for our typical trail conditions 🙁

ie zero as it’s direct 1:1 drive

There will always be some drag, it may be least, but that doesn’t mean no drag.

On the Rohloff, noted the other thread about dodgy bearings, doesn’t sound to good on something costing that much. Particularly if they have to go back to Germany for service.

There will always be some drag

OK, yes in the main bearings, same as any other hub, but if there’s no relative movement between the internal gears they cannot cause friction.

The Acros A-Gear setup is fully rebuildable. There is 248 individual parts inc 29 bearings that make up the entire set. Because each and every part is made in house, in Germany, a rear mech or shifter etc can be rebuilt from the ground up and you will never need to replace and entire mech.

Provisional pricing is $2300USD or around 1500Euro’s/1400GBP.

The 2 small hoses will be combined into one housing per shifter for the production model. Depending on the frames cable routing, its also possible that all 4 hoses can be combined from the headtube back to neaten everything up.

A-Gear was a concept by Christian Muthers that has been realised and bought to life by Acros. Acros had the tooling, finances and power to bring the project to the market and Christian now works for Acros in a development role.

J