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Another Rollo Elf thread

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lee hawkins 120/03/2014 13:29:12
100 forum posts

I was reading a recent thread regarding the Rollo Elf, I didn't want to hijack that thread so I started this one.

I have got a few questions regarding the (Sturmey Archer Gear hub), I quite like the idea, especially while I have a project running building myself a lathe, I have been taking designed Ideas from lots of different lathes, never came across this one though, do anyone out there have one of these that they use regularly

The lathe I am building is about twice the size of the Rollo Elf, it will look abit old fashioned in design, but thats no worries for me

Are these bicycle hubs strong enough?

As a gearbox for a lathe, do they actually make a difference in the operation of the lathe ?

Do you actually notice a difference when you change gear ?

Regards

lee

Roderick Jenkins20/03/2014 14:08:25
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1776 forum posts
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Strong enough? Yes. A cyclist can sustain about 1/3 horse power and a big guy stamping up hill puts a considerable torque through the hub.

As far as the gearbox is concerned there is the possibility of confusion here. The SA hub acts like a gear head lathe and so provides a speed change equIvalent to changing the belt on the pulleys. This gives a slow speed but higher torque or low torque and higher speed, depending on the ratios, which is necessary to cover the machining of differing diameters and materials.

I hope this is not too simplistic,

Rod

Ady120/03/2014 14:44:52
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3463 forum posts
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Theres a video somewhere of the sturmey archer factory before they sold up

Gigantic machines the size of a bungalow to make tiny supertuff accurate and reliable bike hubs

camper20/03/2014 16:51:06
11 forum posts

Have a far eastern 5speed version on a tandem it seems bullet proof, but some of the birmingham ones were a tad iffy. As an aside a hub brake makes decent clutch my 1930 springfield has used a bsa bantam rear for 30 years it is now worth more than the lathe

Neil Wyatt20/03/2014 20:24:00
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As a teenage I regularly had the red scar five inches above my ankle to prove the SA hubs didn't always work... it was often down to cable stretch.

Neil

daveb20/03/2014 20:31:35
609 forum posts
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Posted by Neil Wyatt on 20/03/2014 20:24:00:

As a teenage I regularly had the red scar five inches above my ankle to prove the SA hubs didn't always work... it was often down to cable stretch.

Neil

You must have been tall or had a ladies bike, the injuries I suffered due to these infernal devices were not visible to the public but nonetheless extremely painful.

Dave

Roderick Jenkins20/03/2014 20:56:09
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1776 forum posts
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With a Rohloff hub you can have 14 speeds and they are supposedly bullet proof: if you've won the lottery!

Rod

Versaboss20/03/2014 21:51:07
417 forum posts
50 photos

I seem to remember that somewhere in the past I 'saved' a S-A hub with the idea to use it for a 3-speed drive. After checking the gearing ratios I came to the conclusion that the differences are much too small to be useful. Has the Rollo lathe an additional way to change speeds?

Maybe someone can tell the gearing ratios of these hubs?

Greetings, HansR.

Keith Long20/03/2014 22:25:01
791 forum posts
10 photos

HansR if you go to the S-A website and click on "hubs" in the navigation bar that comes up you'll find the hubs listed and you can click on specs which include the gear ratios. Now those will be for the current product, so no idea how they will relate to "vintage" units, but it will give you some idea of the ratios.

Keith

Edited By Keith Long on 20/03/2014 22:25:35

frank brown21/03/2014 06:22:17
436 forum posts
5 photos

Years ago i had ST gears on various bikes and seem to remember that they were 1: .8, 1, 1.2 not a very large ratio change for a lathe. Also I was in the habit of bending the spindle, in the end I could change one in an hour, so I do not think there torque transmission would be enough for anything other then a watchmakers lathe.

Frank

lee hawkins 121/03/2014 06:56:42
100 forum posts

Thanks everyone for posting, a few different opinions

So it looks like the Hubs have a questionable strength, but like HansR has said, the ratios are not much good, I wouldn't understand the ratios that would be good for a lathe, on a bike you soon would know soon as you start to peddle

On the Rollo elf, would it be down to the pulleys that were fitted, pulley size in conjunction with Hub would surely make a difference

I have been searching around for videos of these lathe actually running, cant find anything out there

Regards

lee

Edited By lee hawkins 1 on 21/03/2014 07:00:57

Neil Wyatt21/03/2014 19:49:21
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> You must have been tall or had a ladies bike, the injuries I suffered due to these infernal devices were not visible to the public but nonetheless extremely painful.

Dave, if you suffered such injuries from your pedals slipping...

Neil

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