What

[Guest Big H]

And then the men in white coats' date=' armed with science came and made it happen....
[/quote']

Next you'll be telling me the earth isn't flat and is only 10,000 years old.

 

Actually only 6500 years old according to creation theology....... the earth being flat...... well, the Flat Earth Society may convince you.

[Piernas Flacas]

Disc brakes on bicycles. What's next? Power steering?

[Sammajoor]

 

Disc brakes on bicycles. What's next? Power steering?

 

Nope electric shifting and auto shifters

 

[Piernas Flacas]

Disc brakes on bicycles. What's next? Power steering?

Nope electric shifting and auto shifters

 

Are they taking away the fun of shifting?

[Johan Bornman]

JB' date=' surely it is the extra leverage offered by disks that saves the forearm muscles more than gritty cables?

Similar to V brakes vs cantilevers. The former have more leverage than the latter. [/quote']

 

Jules, this is something that I've pondered often, especially when that grit starts to work me up. My experience with clean cables it that it  leaves me less fatigued afterwards. However, I'll admit that this is a subjective statement and you know that I steer away from those. That's why I commented that I'd like to try hydraulic Vs. My perception is that a clean set of cables make me do less forearm work than a bad set.

 

This is in the context of top end Vs vs top end discs. The stopping force and muscle work required to stop from similar speeds are similar. Poor Vs compare very poorly to even average disks. With poor V-brake pads the brake force required (and hence arm work) is noticeably more.

 

Speaking of leverage. It is not so much the leverage as the mechanical advantage that makes the difference insofar the force on the discs or rims, with both levers essentially two-finger shorties.

 

The old cantilevers had a variable mechanical advantage as the straddle cable angle changes in a non-linear fashion with travel on the lever. With Canti's you had the least mechanical advantage at the point where the pads just contact the rims and the best advantage when they're 5mm away from the rim. It was a true braking paradox.

 

A disc brake can be made with any mechanical advantage and it is up to the manufacturer to decide on the master/slave cyclinder ratios. With too much advantage, the brake become unpredictable. With too little it becomes spongy and you may run out of lever travel before you stop.

 

I think at the top end, or even serious amateur end of the market disc brakes have more advantages for the rider than Vs and the latter will be the domain of one or two cranks like me or weight weenies.

 

The average mountain bike needn't have discs and the rider will not suffer for the lack of them. I just lament the youngsters that come through my doors to learn about bike maintenance and the first thing they start asking is where to find cheap discs. They should be asking for training programs, not better components.

 

 

 

 

 

 

 

[Jules]

Can't wait for internal hub gears to become the standard on MTBs. imagine no: dropped chains, chainsuck, mis-shifting, stuff caught in cassettes, bent derailler hangers, chain hitting stay when going over obstacles etc etc. The advantages of a single speed, but with gears

[TheLegend]

Rohloff 

[Johan Bornman]

Can't wait for internal hub gears to become the standard on MTBs. imagine no: dropped chains' date=' chainsuck, mis-shifting, stuff caught in cassettes, bent derailler hangers, chain hitting stay when going over obstacles etc etc. The advantages of a single speed, but with gears [/quote']

 

I've done such a bike for a friend. He purchased a bike with the right drop-outs for a Rohloff 14-speed internal gear hub and I built the wheel for him and assembled the bike. He's very happy with his bike and I can see why. When the sprockets wear, you turn them around and use the other side. The chain is a cheapo and beefy 8-speed and everything's pretty strong.

 

However, building a reliable wheel with such a large hub is a problem, especially on a smaller MTB wheel. The spokes arrive at the rim at an obtuse angle, causing spoke breakages at the nipples.

 

I calculated the arrival angle beforehand and we arrived at what was then a novel approach. Other manufacutures also do it today and I wish I patented my idea. What we wanted to achieve was a rim where the spoke hole allowed the nipple to swivel quite a lot and therefore putting no bending forces on the spoke. We used a Mavic rim of the type meant for the fat aluminium spokes and oversized screw-in nipples. We then paired this up with standard nipples. It looked quite weird but the spokes remained straight.

 

I think his wheel is now sorted. Kurt moved to Tulbach and rides about 80 kms a day (retired). By now I would have heard from him had it not worked.

 

The biggest problem I foresee is that the frame as to be designed for the hub and that leaves you with limited choices. If I remember correctly, his frame was an Eagle Something and could only be had in steel, made in the UK, at a price.

 

Sort out those little nigglies and the internal gear bike will be a winner....bar market prejudice.

 

 

[MintSauce]

 

Can't wait for internal hub gears to become the standard on MTBs. imagine no: dropped chains' date=' chainsuck, mis-shifting, stuff caught in cassettes, bent derailler hangers, chain hitting stay when going over obstacles etc etc. The advantages of a single speed, but with gears [/quote']

 

 

Rohloff 

 

 

+1

 

Looked at one for the first time a few weeks ago at Crosstown. There's one in my future. Is their newest offering available yet....supposedly much lighter and offering trigger shifters...?

 

 

 

 

[TheLegend]

 

 

Rohloff 

 

 

+1

 

Looked at one for the first time a few weeks ago at Crosstown. There's one in my future. Is their newest offering available yet....supposedly much lighter and offering trigger shifters...?

 

 

 

I can't comment on this but my next MTB, which will be a steel one, will get the Rohloff. Then, when I have money again, I'll get a tourer, with a Rohloff, and then ..... agh, dreams are so nice to have

 

[MintSauce]

 

The biggest problem I foresee is that the frame as to be designed for the hub and that leaves you with limited choices. If I remember correctly' date=' his frame was an Eagle Something and could only be had in steel, made in the UK, at a price.

 

[/quote']

 

I'm pretty sure they can now be used on any frame. They supply a bracket that fits on the left rear dropout where the cables attach.

 

I've seen the hub used on a FS bike like mine with a chain tensioner, as you would when converting a normal frame to SS.

 

It seems the major gripe at present is the weight. The hub weighs over 1500 grams, but then you're removing the front and rear derailleur, cassette and front shifter so it's not that big a deal.

 

Some people are concerned about reliability. A friend of mine learnt frame building in a custom shop in Germany. 70% of their frames were Rohloff specific.

 

A customer once brought a bike in for service. The rear cog was so worn out that they couldn't get a chain-wip to bite in order to remove it. The owner claimed the bike had done 60000km without a single service to the hub. It's supposed to have an oil change once a year.

 

He says that at the time Rohloff was running a hub on one of it's team bikes without any oil as a test. The hub had been ridden for four seasons without a single problem!

 

 

 

[TheLegend]

 

 

Some people are concerned about reliability. A friend of mine learnt frame building in a custom shop in Germany. 70% of their frames were Rohloff specific.

 

they built touring bikes' date=' hey?

 

 

 

A customer once brought a bike in for service. The rear cog was so worn

out that they couldn't get a chain-wip to bite in order to remove it.

The owner claimed the bike had done 60000km without a single service to

the hub. It's supposed to have an oil change once a year.

 

He

says that at the time Rohloff was running a hub on one of it's team

bikes without any oil as a test. The hub had been ridden for four

seasons without a single problem!

awesome!

 

[Piernas Flacas]

I found this on Wikipedia. The weight is considerably more:

 

The weight can be compared with a high quality derailleur system (Shimano XT):

Speedhub 500/14 CC-OEM	High quality derailleur system
Gear hub: Twist shifter: Shifter cables attachment: Total weight: 1,715 g 118 g 14 g 1,847 g

Rear derailleur: Front derailleur: Crank wheels: Cassette: Rear hub: Crank wheels: Additional chain weight: Additional spokes weight: Total weight:

230 g 130 g 250 g 260 g 370 g 62 g 30 g 25 g 1,357 g

The Speedhub weighs about 0.5 kg more.

A new version (currently in development, with testing due to begin in 2009) will weigh 1400g, be 20% smaller and have a larger overall ratio of 580%.

[Sean Badenhorst]

 

Yep' date=' one needs to differentiate between braking force and required hand power. I've done downhills where my hands are aching afterward. [/quote']

 

 

I thought that only happened to gorillas...

 

 

 

 

 

 

[Sean Badenhorst]

Braking is over-rated. What ever happened to good old skill?

 

 

 

 

 

 

[dirtrider]

True but the people in white coats say that if you brake at the right place at the right time with the right brakes (which will be disks) you should be much faster !