Sturmey Archer Gearing on a BMX.........I'm not crazy BTW!!

[moley]

I've been thinking about getting some gears on a BMX for next spring.

Not for racing............just for getting to work and back............up hill down dale.    Instead of using a MTB for some steep hill work..........use a 20" with gears, where a standard 44/16 would never get up.   I can only just get up it on my lowest MTB 27 Speed Gear.   And for long flat/downhill stretches then I can crank it up in a high gear and get some speed up.  Singlespeed is okay for the track, skatepark and ride down the road to the offy but if my BMX had a few gears then I'd use it for some epic rides instead of my MTB and I have the perfect donor frame and forks for it too.

A browning or a 2 speed freewheel job might be a laugh but I've been thinking about my old Chopper and thought........why the hell not.   I had my chopper for about 2-3 years and never had a problem with the gears.   

My mates kid has a 16 inch with sturmey archer type gears on it so a BMX can't be impossible.

From what I've researched Sturmey Archer do a 5 speed Freewheel hub with 111mm (old spec) 113.5mm (new spec) over locknut dimension.  I presume thats the cone locknut to cone locknut so the frame has to have a 111/113.5mm gap which seems about right for a BMX.     

Gear ratio

Gear 1 - 62.5% (-)37.5%
Gear 2 - 75%    (-)25%       (Gear 1 +20%)
Gear 3 - 100% Direct Drive (Gear 2 +33%) 
Gear 4 - 133%  (+)33.3%    (Gear 3 +33%)
Gear 5 - 160%  (+)60%       (Gear 4 +20%)

Has anybody tried sturmey archer gears on a BMX (or is this sacrilegious) or has anybody sturmey archer experience?   

I expect some witty replies!!!! 

[dan-dare]

forget the ratios ian, up creek and down to keswick on this weapon of lakeland destruction.

 

[kingkeef]

Go hang your head in shame

[HEYWOOD BMX]

  Blasphemer! Aren``t most BMX hubs now 110mm? Sure Diggler has a spreader you could borrow..

[bof]

http://www.kinetics.org.uk/html/rohloff1.shtml

[moley]

http://www.kinetics.org.uk/html/rohloff1.shtml

£870!!! 

I thought the Sturmey archer 5 speed was expensive at £124!!

...........and I bet that rohloff1 wont fit a 110mm rear end!!   

[Gary72]

I have an acs 2 speed freewheel you can buy, If the Grifter gear fails.
Or if you are feeling flush
http://www.profileracing.com/estore2/index.php?productid=13
 

[griff]

the sturmey archer gears on both my old choppers bitd were shite
and my mate's grifter

every time you selected '2nd' going up the slightest incline the cranks would spin like it was in neutral and send you flying forwards - dangerous esp on a 2nd hand mk1 chopper with the gear knob missing (I'm lucky to still have gonads after riding with a metal skewer pointing at em for all that time)

[edit]

just had a look for a pic of the bike in question and found this - was just like this one before me and my dad spray painted it matt black on the washing line (minus the gear knob of course)
(should have kept it if they're going for that much now!!)

[moley]

I have an acs 2 speed freewheel you can buy, If the Grifter gear fails.
Or if you are feeling flush
http://www.profileracing.com/estore2/index.php?productid=13
 

2 speeds aint enough...............it needs to be 3 minimum to be worth the effort of building it.   5 sounds decent.   Bofs 27 speed is indecent..........but its £870 and it will only fit a 135mm frame spacing minimum.

What would you need to shift gear on the 2 speed ACS?

the sturmey archer gears on both my old choppers bitd were shite
and my mate's grifter

Sounds like you didn't know how to tune the gearing!!

If I decide to gear up then I wont be using a TT central Gear knob either.    I've had a few close calls with my knackers too!!! 

[HEYWOOD BMX]

  Those Rohloff hubs are mega heavy.A local MTBer has just spent a million quid (well,a sh*tload) on a custom ti frame/fork/bar setup & put a Rohloff hub on it,thus increasing the weight tenfold!

[kdw712]

should have had a bid on this 

prob worth it just for the rim

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=350405961088&ssPageName=STRK:MEWAX:IT#ht_642wt_1139

[griff]

I have an acs 2 speed freewheel you can buy, If the Grifter gear fails.
Or if you are feeling flush
http://www.profileracing.com/estore2/index.php?productid=13
 

2 speeds aint enough...............it needs to be 3 minimum to be worth the effort of building it.   5 sounds decent.   Bofs 27 speed is indecent..........but its £870 and it will only fit a 135mm frame spacing minimum.

What would you need to shift gear on the 2 speed ACS?

the sturmey archer gears on both my old choppers bitd were shite
and my mate's grifter

Sounds like you didn't know how to tune the gearing!!

If I decide to gear up then I wont be using a TT central Gear knob either.    I've had a few close calls with my knackers too!!! 

no kidding moley - i was 10 

not that 30 years on i'm any better with a spanner

[moley]

Those Rohloff hubs are mega heavy.A local MTBer has just spent a million quid (well,a sh*tload) on a custom ti frame/fork/bar setup & put a Rohloff hub on it,thus increasing the weight tenfold!

The 5 speed SA hub is around a kilo,  the Rohloff hub is about twice that for 27 gears!!

[SteveG]

I built up a Mountain bike wheel with a 3 speed hub in it. It was ok for riding around on but not so clever off road.
You would need a correctly spaced gear shifter I think I used the lever that worked the front mech to control the MTB one.
With everything set properly on hub I didn't have a problem and fortunately it didn't slip.

My Brother was into mountain bikes at the time and bought a 5 speed hub (I think) the idea being that you wouldn't have a chain flapping about plus a hub gear stays clean.
For the ultimate maintanance free bike you could get a Sturmey Archer with a coaster and gears.

[James Nada]

Moley - I have an old folding bike with 20" wheels and 3 speed Sturmy Archer (or some kind of copy). I think it the rear wheel would fit a BMX.

Anyway, it's yours if you want it (it may be useful on a prototype at least).

[Dark Diggler]

Moley.....your a mong

[Jon The Bassist]

For fitness you should keep it single speed 

Unless you've got a seriously steep hill that's impossble to get up.  On my ride to work I go from the lowest point in Harrogate to the highest, which is a decent climb. It's only about 4 miles but it really gets your heart rate up as you're out of the saddle for a lot of the way.

[James Nada]

Unless you've got a seriously steep hill that's impossble to get up. 

This is the Lake District Jon, we only have two types of hills - Seriously Steep and Fookin' Seriously Steep.

[OrgasmDonor]

Unless you've got a seriously steep hill that's impossble to get up. 

This is the Lake District Jon, we only have two types of hills - Seriously Steep and Fookin' Seriously Steep.

and obviousy mole 

[Badbaldie]

hills are no problem to a mole ...... they just tunnel threw. 

[moley]

Moley.....your a mong

I thank you for your encouragement and support!!

hills are no problem to a mole ...... they just tunnel threw. 

It could take weeks to tunnel through!!! 

For fitness you should keep it single speed 

Unless you've got a seriously steep hill that's impossble to get up.  On my ride to work I go from the lowest point in Harrogate to the highest, which is a decent climb. It's only about 4 miles but it really gets your heart rate up as you're out of the saddle for a lot of the way.

Why keep it singlespeed?   The rohloff system is good but expensive but think about the system.   Its clean.   No derailleurs, No slack chain that needs tensioning, no trailing chain under the freewheel that you have worry about clearance.    Sturmey Archer are taiwanese now so the tolerances on the machinery are far better than the English made ones (from the 60's when the quality went downhill) because they ended up chucking out all of the machinery because it was so out of tolerance and built their own.   If 44/16 is your neutral gear then with a 3 speed the lowest gear would be -25% and the highest would be +33% above 44/16.   For spinning exercises you could knock it into low gear and for power you could knock it into high gear when your sprint training.   Feel that burn.   And you could also use it for general cycling.   With 5 gears I reckon it could be used for the lake district and the big mountains.    Just set the neutral gear so that the lowest gear (62.5% of neutral ) is suitable for the steepest hill you'll encounter and the highest (160% of neutral) should be fine for any decents or on the flat.

5 Speed Gear Calculation Chart Based on 44/16t Gearing 20x175 180mm Crank (51.4" Travel Distance)

S/A Gear	BMX Gear (closest)	Distance	Ratio	Inc/Dec %	Gear Inc%
1	28/16	32.1"	62.5%	-37.5%	Gear 1
2	33/16	38.5"	75%	-25%	Gear 1 +20%
3	44/16	51.4"	100% Neutral	Direct Drive	Gear 2 +33%
4	59/16	68.5"	133%	+33%	Gear 3 +33%
5	70/16	82.2"	160%	+60%	Gear 4 +20%

I think a normal 27 Speed 26" MTB gearing is 44/32/22t Sprocket and 9 Speed SRAM (12/13/14/15/17/19/21/23/26) giving low gear of (22/26t) of 21.9" and high gear of (44/12t) of 95.1" distance travelled!!    Sturmey Archer 5 Speed with 44/16t gearing would give 32.1" (Low), 82.2" (High) and normal 44/16t Neutral middle gear.

It should give some usable gears!!

Moley - I have an old folding bike with 20" wheels and 3 speed Sturmy Archer (or some kind of copy). I think it the rear wheel would fit a BMX.

Anyway, it's yours if you want it (it may be useful on a prototype at least).

Is it fully operational with gear selector, cables etc, etc?   Also how is the cable gear selector mounted to the frame?  Metal clips or welded mounts or neither?

The big point is hub width.  It would need to fit into a 110mm frame!! 

I think a prototype made out of a Falcon Pro Flyer is on its way!!!   

Diggler wont be laughing when he hits a steep incline on MTB and I wizz pass on my 20" Falcon Pro Flyer!!    Take that Diggler and stick your negative energy where the sun dont shine!!! 

[Jon The Bassist]

I suggested keeping it single speed purely from the point of view of givng you a good workout, not to get you there quicker or owt. In my experience you get a good burn in the muscles going uphill, then practice your spinning when going downhill.
I totally understand about not wanting deraileurs with all the crappy angles for the chain, difficulty in maintaing it all etc and it generally being a rubbish, flexy system. If a hubgear works for you then go for it. Most of my fitness gains this year have been from commuting, so I highly recommend it .

For informaton my OM Flyer has a rollout of 60" which is hard work up the steeper hills but great on the flat and downhill.

[griff]

go for it moley! not like you don't have other bikes to play on 
look forward to seeing the results!

cheers

griff

PS you should put a twist-shift & some grifter decals on it 

[James Nada]

Moley - I have an old folding bike with 20" wheels and 3 speed Sturmy Archer (or some kind of copy). I think it the rear wheel would fit a BMX.

Anyway, it's yours if you want it (it may be useful on a prototype at least).

Is it fully operational with gear selector, cables etc, etc?   Also how is the cable gear selector mounted to the frame?  Metal clips or welded mounts or neither?

The big point is hub width.  It would need to fit into a 110mm frame!! 
   

Diggler wont be laughing when he hits a steep incline on MTB and I wizz pass on my 20" Falcon Pro Flyer!!    Take that Diggler and stick your negative energy where the sun dont shine!!! 

Yep, proper gear selector and cables attached etc.  It prbably needs a lube up though. 

I think the cable gear selector is mounted via clips rather than welded mounts - not sure though. Dunno about the 110mm frame either -the bike is under a pile of shite at the moment. I'll find out.

[moley]

I'll find out.