Why use internal gear hub

[novetan]

I see most foldable bikes with 3 sp and abv are mostly installed with internal gear hub . While I understd hub has longevity and easier to maintain than std derailleur, it is so much heavier and costlier. And esp 3 sp, why Brompton not using the std cog with derailleur? Is it because of folding issuing? I owned a road bike, it is not difficult to maintain. And for those weight weenies that try to pinch a few grams here and there, the hub is the part that save you a ton. And for that matter, why 6 sp isn't using cog as alternative or an option?

 

[raleighnut]

I see most foldable bikes with 3 sp and abv are mostly installed with internal gear hub . While I understd hub has longevity and easier to maintain than std derailleur, it is so much heavier and costlier. And esp 3 sp, why Brompton not using the std cog with derailleur? Is it because of folding issuing? I owned a road bike, it is not difficult to maintain. And for those weight weenies that try to pinch a few grams here and there, the hub is the part that save you a ton. And for that matter, why 6 sp isn't using cog as alternative or an option?

It'd be the folding issue with a derailleur.

 

[Cycleops]

You have to think who Brompton's main customers are. They are commuters who require their mount to be clean and easy to fold, they can't be doing with an oily protrusion which may get in the way of a fold.
Other makers do use a derailleur on their folders but might not be aiming them at this sort of user, they have hub gears or SS for them. Plus with 16" wheels the mech is too close to the road picking up dirt and damage.

 

[Fab Foodie]

....also, folders are primarily designed for short distance/commuting for which speed and weight are not the issue, however, simplicity, low maintenance, easy cleaning are important issues. The hub is a winner, PLUS, you can change gears without peddling which in urban commuting is pretty useful.
Some Bromptonistas fit 14 spd Rohloff hubs tho....

 

[Rocky]

I love the hub on my Brompton. It’s low maintenance, goes on for ever and easy to clean. The ratios are fine for everything I’ve ever done on it, including all but the steepest hills.

 

[HMS_Dave]

I think you skimmed off the positives too easily there. It is as you say, low maintenance and have a long life which are excellent reasons given the target customer. At the end of the day it is made of steel it was never going to be as light as it could be but with that it has very long life and strength. They're folded and picked up with little complaint. With the amount of years they've been going like that and the amount of people who buy them if say not a lot what much changed about them.

 

[Tenkaykev]

Mrs Tenkay has a 14 speed rohloff hub on her Roberts tourer.
It is a wonder of engineering excellence but it's quite a lump.
I'd wondered about whether a six speed version would be practical so they could drop the derailleur, but I suppose it's a matter of cost, complexity and demand.

 

[bikegang]

Standard snap ring hub can only take up to 3 external cogs. Which can be easily modded with Unibody cog set and compatible to most stock parts.

X3 Unibody cog set

Anything over 3 will require some extensive modifications, such as longer tensioner arms, clamp or filing the frame end, longer custom free hub body (wheelset) or evern a dedicated chain puser, DR spring set.

Custom longer free hub body for 4 cogs

This modification that uses 7 speed sprocket cassette (11-28t) is probably pushing the limit. You can tell the chain pusher and jocky wheels are all new design to allow longer and smooth travel between sprockets.

Linear chain push 7 speed 28T external cogs system


I will think Duo chainring (33/54T) with 4 speed external cogs (11-14-17-23T) might be a best combination to replace BWR 6 speed (302%). It will save quite a few gram and a wider gear range of 345%.

33/54T Duo-chainring

 

[Schwinnsta]

I think its partly historical, when it was invented. For a 16 inch wheel, a standard derailleur would have been very low and not as robust.

 

[berlinonaut]

And esp 3 sp, why Brompton not using the std cog with derailleur?

The do - they are offering the 2speed. Knowing both, personally I prefer the 2 speed Brompton over the 3-speed-hub one and can not really see a disadvantage but many advantages. Still many buyers prefer the 3-speed hub over the 2-speed, so why should Brompton not be offering it?

 

[mitchibob]

Mrs Tenkay has a 14 speed rohloff hub on her Roberts tourer.
It is a wonder of engineering excellence but it's quite a lump.
I'd wondered about whether a six speed version would be practical so they could drop the derailleur, but I suppose it's a matter of cost, complexity and demand.

Isn't that what Mark Beaumont used during this solo around the world record?

 

[MichaelW2]

A hub gear runs cleaner than a derailleu system. Cleanest is hub gear + belt drive but you can't do a Brompton fold with a belt.
I use 8 speed hub gear and find it clean, simple and low maintenance. Mine has about 30k miles

 

[Once a Wheeler]

I am a great fan of derailleurs but from an engineering point of view they have their shortcomings. No engineer likes a traction system where the elements run out of alignment and , obviously, the derailleur depends on misalignment in order to function. Similarly, a system running in a closed compartment, such as a hub, is protected from the elements and easy to keep lubricated. I have often wondered why no-one has commercialized a gearbox set in the bottom bracket. It must have been tried out at some point. Perhaps it is the moment for an innovator to take a new look at the concept with modern materials and techniques. Such a gearbox would mean the cranks no longer drive the chainwheel directly: instead, the cranks would drive into the gearbox and the gearbox would drive the chainwheel. So, over to the innovators. Meanwhile, I will keep my gears where I can see them (and maintain them).

 

[MichaelW2]

I am a great fan of derailleurs but from an engineering point of view they have their shortcomings. No engineer likes a traction system where the elements run out of alignment and , obviously, the derailleur depends on misalignment in order to function. Similarly, a system running in a closed compartment, such as a hub, is protected from the elements and easy to keep lubricated. I have often wondered why no-one has commercialized a gearbox set in the bottom bracket. It must have been tried out at some point. Perhaps it is the moment for an innovator to take a new look at the concept with modern materials and techniques. Such a gearbox would mean the cranks no longer drive the chainwheel directly: instead, the cranks would drive into the gearbox and the gearbox would drive the chainwheel. So, over to the innovators. Meanwhile, I will keep my gears where I can see them (and maintain them).

Schlumf drive
Pinion
Truvativ Hammerschmidt

The are expensive and not widely used.

 

[raleighnut]

I am a great fan of derailleurs but from an engineering point of view they have their shortcomings. No engineer likes a traction system where the elements run out of alignment and , obviously, the derailleur depends on misalignment in order to function. Similarly, a system running in a closed compartment, such as a hub, is protected from the elements and easy to keep lubricated. I have often wondered why no-one has commercialized a gearbox set in the bottom bracket. It must have been tried out at some point. Perhaps it is the moment for an innovator to take a new look at the concept with modern materials and techniques. Such a gearbox would mean the cranks no longer drive the chainwheel directly: instead, the cranks would drive into the gearbox and the gearbox would drive the chainwheel. So, over to the innovators. Meanwhile, I will keep my gears where I can see them (and maintain them).

Pinion make a front 'gearbox' drive.