Cycling UK Forum

I've recently acquired two bikes with hub gears. After a few months of using them I'd say that nothing beats a derailleur for low weight and efficiency. Have you considered a growing trend of going from expensive 10 and 11 speed systems to cheap and reliable 8 speed systems, something like Shimano 2 x 8?

SJC can't supply the correct sprocket at the moment so I'll buy a dished one off Ebay and see what happens.

Tipping oil in seems to have worked. I have regained a few km/h that seemed to have gone missing even though I was pedalling hard. I'm surprised how cheap the hubs are considering their internal complexity.

I've read how they work now: https://www.sheldonbrown.com/internal-gear-theory.html
Very interesting it is too. I'm surprised at how cheap the gearboxes are.

The unity ratio is usually a direct link from input to output so minimal losses. Some of the Shimano units go down and back up to give ratios near unity so they're pretty lossy. I've been happy with the bike's performance in general and I bought a hub geared bike so I could find what they're like.

I want to gear down my 5 speed SA hub to give the same bottom ratio as mu Nexus 8 hub.
The hub ratios are 0.64 vs 0.53 so I need a 20% reduction. The bike has an 18 tooth sprocket so I need to reach 21 or 22 teeth.

The bike has a flat 18T sprocket, CSIRW type. The part numbers are listed in https://www.sturmey-archer.com/files/ca ... RX-RK5.pdf

The spec shows a 1.2 mm offset due to dished sprockets. https://www.sturmey-archer.com/files/ca ... %20C50.pdf

I've looked and the flat 22 T sprockets are not readily available online but there are loads of the dished version. Will it matter if I use a dished sprocket? On a derailleur bike the chain runs at an angle most of the time.

I've done some searching and it appears that this is not a new question! I need to check to see if there are spacers on the existing hub then. https://www.bikeforums.net/bicycle-mech ... stion.html

I've noticed that the lowest gear is quite rough and lossy on both hubs. My opinion of the SA hub has gone up since this happened.

I took the left hand cone off this evening and poured about 50ml of gear oil into the hub. That seemed to make turning it by hand a lot easier and a quick ride suggested some improvement. I did a rough and ready coast down test on the road with both bikes and they were identical.

Essentially you seem to be saying that hub gears are a bit lossy. They're quite heavy too. Having said that, I was quite surprised how fast my Katu 40 (5 speed SA) was when I first got it so it can't be that bad. Hopefully I'll come to appreciate the benefits of them being sealed with time, though I'm starting to rediscover my love of derailleurs.

Thanks for the info. I've been riding my 5 speed bike this weekend and it feels faster/easier to pedal to me. It did cross my mind that basic cleaning and lubrication of the seals might bring some benefit. I'll take a look at it.

I'll try to do some coast down timings on a flat road to see if it is measurable or just a suspicion.

I've got 2 Orbea Katus - one with a 5 speed Sturmey Archer hub, the other with a Shimano Nexus 8 speed hub. The 8 speed bike is the better bike (disc brakes and hub dynamo) which I bought after liking the 5 speed bike so much.

I've found the effort to ride the 8 speed bike seemed to have gone up recently. I did the classic test of spinning the back wheel round and found that it did come to a stop far quicker than I would have expected. I compared the two bikes and the 5 speed is smooth when the cranks are rotated backwards by hand but the 8 speed seems to have far more resistance. Rotating the sprocket by hand (with the chain removed) then it feels a bit notchy and not as smooth as I would expect.

The hub came on a nearly new bike so I doubt it has covered many miles in the year or two since manufacture.

I think there's something wrong with the hub. Are there any known issues? Someone told me to adjust the bearing cone preload. I could do that but I'm minded to hand the whole hub over to a local bike shop and ask for an opinion.

Hello, we've started up a group to campaign for better cycling and walking infrastructure and facilities in the Stroud area.
Someone has already organised a demo ride for Sat 25th June due to a road widening scheme that has made things worse for active travel.
https://www.facebook.com/events/743499256199445/

It would be great to have support for this. Please share the event.
We're also on twitter at https://twitter.com/StroudActive