RADBMX.CO.UK
Technical & Reference Section => Tech and Restoration => Topic started by: garethgeezer on April 24, 2007, 10:58 AM
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Just fitted some 16" Acorn Freestyles to my son's bike, they look great but he is very disappointed as after about a mile of riding the freewheel started to play up - it slipped then locked up, slipped again etc etc. Easy I thought, until I got home and checked it out. It is a Sturmey Archer hub, I think, so it does not have a normal BMX freewheel but is more like a shopping bike hub. It has 'SA' stamped on it, also 'AW' and '85'. There are tabs that locate the hub into slots on the wheel centre and the whole thing is secured with a circlip on the other side.
I don't know how to fix it. Does anyone have one of these they don't need that they would be kind enough to sell to me? or does anyone know how to replace/repair the freewheel part which I'm guessing is inside the hub? Thanks!
Any help or advice would go towards cheering up my son :)
(http://img172.imageshack.us/img172/5255/hotrockmagvm8.jpg)
(http://img172.imageshack.us/img172/8092/acornhubok6.jpg)
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That looks like a coaster hub to me, minus the ancor arm.
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I did consider that, but there doesn't seem to be anywhere for an anchor arm to go, plus it sounds like a regular freewheel when it is working. Anyone else have this sort of hub on an Acorn wheel? Anyone else got Acorns?! (I know they're not very popular)
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If you dont have the coaster arm on , i expect it will rotate like a freewheel
On the advert, it says
Rear Sprocket thread : 1.37 inch x
24 T.P.I. suitable for all standard
sprockets
So i would expect a normal freewheel.
I might have a review of Tuffs v acorns so i will take a look
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Hi,
Found the magazine, but rubbish pics so could not tell.
Can you take another pic of the side that the chain does not go on to
I still thik this is a coaster hub
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Fixed it! I took the plunge and dismantled the hub last night (it was that or do the washing up). I undid it all and waited for springs, bearings and bits & pieces to fly everywhere but it all came apart very well. It is a Sturmey Archer single speed hub, very like a Raleigh Chopper style rear hub, but only one set of planetary gears in there. A lot of the parts are identical, it even has the same axle which is hollow on one side for the gear chain if it had gears.
The fault was this: The pin that forces the drive clutch in place had broke, so that's why the freewheel locked up then splipped as the loose bit of pin was rattling around inside and got jammed in the gears. Without that pin in place, the drive clutch was able to slide away from the drive pins so all drive was lost as soon as that happened. I machined out a suitable sized (10mm ID) nut so that it forced the drive clutch to connect with the drive pins once the clutch spring was fitted and hey presto it all runs smooth with a lovely shopping bike tick tick tick tick when freewheeling. I would have taken phots but I just tought I'd have a look at it and before long it was back together. My son is well happy that the mags are back on :)
Thanks to adeshere for the advice, I think the 16" hubs are completely different to the 20" ones from what I can work out. And no sign of a coaster either, just an unnecessarily huge hub!