rogerzilla
Legendary Member
Gears in the BB have to cope with full pedalling torque, which is similar to that from a large petrol engine. They need to be bigger and heavier than they do at the rear hub.
Why use internal gear hub
- Thread starter novetan
- Start date
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Tigerbiten
Guru
Small wheel folders tend to have short chainstays.
This makes the angle of the chain in first and top gear a lot more extreme once you go to a multi sprocket cassette.
Therefore a bigger risk of it jumping of the chainring.
This makes the angle of the chain in first and top gear a lot more extreme once you go to a multi sprocket cassette.
Therefore a bigger risk of it jumping of the chainring.
Fab Foodie
hanging-on in quiet desperation ...
- Location
- Kirton, Devon.
I added a Stronglight 50:36 standard square-taper cheapo chain set to my S6L and it works a treat :-)
FrankCrank
Old layabout
Bromptons have been around for 40 years now, and Sturmey Archer 3-speed hubs for over 100 years. Guess they're both doing something right.
rogerzilla
Legendary Member
Also, for folding reasons, Bromptons want a narrow rear spacing (I think it's about 112mm). Modern derailleur hubs are at least 130mm.
welsh dragon
Thanks but no thanks. I think I'll pass.
I have a nexus 6 speed hub gears on my bike . It's brilliant. No mess no fuss and literally no maintenance in the 4 years I have had it. What's not to like.
I am a huge fan of hub geared bikes. I have 2 x Rohloff geared Thorn bikes, a Brompton and a Nexus hub geared belt drive bike. The latter being almost exclusively used for commuting 20 miles per day to work in all weathers for over 10 years prior to my retirement in 2017. I've never had a single problem with any of my hub gears.
I think the negative often expressed about hub gears being heavier in weight is more often a spurious argument, as with most hub gear set ups there is only one chain ring, no front or rear derailleur and no cassette. Also, the simplicity of hub gears makes it a joy to not have the regular hassle of having to re-index derailleur gears as well as having the advantage of longer chain life.
I think the negative often expressed about hub gears being heavier in weight is more often a spurious argument, as with most hub gear set ups there is only one chain ring, no front or rear derailleur and no cassette. Also, the simplicity of hub gears makes it a joy to not have the regular hassle of having to re-index derailleur gears as well as having the advantage of longer chain life.
roley poley
Über Member
- Location
- leeds
no dishing = stronger wheel ..one size spoke fits both sides of the hub if broken on tour
raleighnut
Legendary Member
- Location
- One of the 'Elite'
They are slightly less efficient than a clean well lubed and maintained derailleur system but better than the gunked up rusty set up often found on commuter bikes.
raleighnut
Legendary Member
- Location
- One of the 'Elite'
It has horizontal dropouts so a Nexus hub should fit nicely.
rogerzilla
Legendary Member
A 3-speed Sturmey-Archer (oiled as opposed to greased) is just about identical to a derailleur system for efficiency, taking into account the loss from the jockey wheels and sprung chain tensioner of a derailleur. It's probably MORE efficient in the middle gear (direct drive). When you go to more than 3 speeds, hub gears start to become less efficient, especially when the drive goes through more than one epicyclic (each of which adds a minimum 3% loss).
SRAM used to make a 7-speed with no cascading of the drive but it had many other problems instead.
SRAM used to make a 7-speed with no cascading of the drive but it had many other problems instead.
berlinonaut
Veteran
- Location
- Berlin Germany
As this thread is about folders and the Brompton in particular: Hub width has been mentioned already, the weight has not. Te 2-speed saves massively weight over a 3-speed on a Brompton - anyone who carries his bike regularly will be thankful for that. In general I do prefer hub gears and within them the Rohloff is clearly my favorite (whereas with many others I dislike the losses in the hub, the spacing of the gears, the limited range, the weight-power-ratio or something else). Which led to me having a bunch of bikes with the Rohloff and some with other hub gears but barely bikes with dreailleurs apart from the 2-speed Brommi. I recently akquired a deralleur bike and must say I am impressed - as it is basically new there are no issues and it clearly feels more efficient than the Rohloff, let alone any other geared hub.
12boy
Guru
- Location
- Casper WY USA
I use 5-20 synthetic oil in my two 3 speed SA hubs and the only downside is seeping oil. I've ridden my surly steamroller with one in -18 C temps and there were no problems. One of the drawbacks to small wheels is the difficulty of getting higher gear ratios and the SA hubs with high 33% higher than the direct drive gear is a good way to do that. I also have a 3 sprocket rear wheel with 11-14-17 sprockets, courtesy of Bike Gang which also works very well although it doesn't have the high gear the SA hub has. It is lighter, though and does not seep oil. Like Fab Foodie I have 2 chainrings, 58 and 38 tooth, so I have a granny gear option for 12% grades although I could use a sub 30 gear inch setup at times. One of the things I enjoy about my Brompton is tinkering with and trying out various options. It really is a fun machine.
