Author Topic: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set  (Read 6684 times)

Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« on: 24 August, 2020, 04:45:02 pm »
Trying to get the 2 cog sprocket set 13 and 15, which I'm told is no longer available

just the cogs would help

https://brilliantbikes.co.uk/brompton-rear-sprockets-and-spacers/414-brompton-sr6-stack.html?search_query=Brompton+Rear+Sprocket+for+SRAM%2FSachs&results=2386

any ideas guys


LittleWheelsandBig

  • Whimsy Rider
Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #1 on: 24 August, 2020, 05:12:33 pm »
They are just standard 13t and 15t SA-style sprockets. Most 6sp Bromptons use 3/32” chain but a few had 1/8” chains. Since you will need to replace the chain anyway, just get 13t and 15t 3/32” three-dog sprockets.
Wheel meet again, don't know where, don't know when...

Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #2 on: 24 August, 2020, 05:25:13 pm »
They are just standard 13t and 15t SA-style sprockets. Most 6sp Bromptons use 3/32” chain but a few had 1/8” chains. Since you will need to replace the chain anyway, just get 13t and 15t 3/32” three-dog sprockets.

Thanks, very helpful - I agree they do look the same, but when I asked the Dealer his reply was:

"There is no alternative unfortunately, not that we have found anyway"

LittleWheelsandBig

  • Whimsy Rider
Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #3 on: 24 August, 2020, 07:12:35 pm »
They are talking bullshit. If the change up to the big sprocket is too slow, just grind the tops off a few of the teeth of the 15t cog to match the existing profile but it will probably be fine as is. Reuse the existing spacer, etc.

https://brilliantbikes.co.uk/brompton-rear-sprockets-and-spacers/389-brompton-sturmey-archer-13t-stack.html
+
https://www.sjscycles.co.uk/sprockets/sturmey-archer-15t-sprocket-332-flat-hsl945/

Both were on the first page of searches. There are other suppliers.
Wheel meet again, don't know where, don't know when...

LittleWheelsandBig

  • Whimsy Rider
Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #4 on: 03 November, 2022, 08:41:10 pm »
https://youtu.be/kigJc-FXpjc is a Brilliant Bikes video explaining how to replace the 13/15t cogs on Sachs 3sp hubs with currently available components. The comments include links to purchase the various bits.
Wheel meet again, don't know where, don't know when...

rogerzilla

  • When n+1 gets out of hand
Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #5 on: 04 November, 2022, 08:30:56 am »
The spares that are more important for these hubs are the big bearing cages (loose bearings wouldn't really work) and the axle key, which can snap without warning.  Both now hard to find, and only overseas.  SRAM pulled the plug on all IGH hubs and spares in 2017.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

LittleWheelsandBig

  • Whimsy Rider
Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #6 on: 04 November, 2022, 09:26:08 am »
Those internal components may be more important but they are definitely less frequently replaced than cogs.
Wheel meet again, don't know where, don't know when...

rogerzilla

  • When n+1 gets out of hand
Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #7 on: 05 November, 2022, 02:38:08 pm »
The bearing cages never seem to last more than one turn of service; they drop several balls when removed.  The axle keys don't wear out as such, but many are weak (it's a crap design, with the hole taking up most of the width) and a clumsy change when stopped can snap them.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #8 on: 06 November, 2022, 08:39:56 am »
The bearing cages never seem to last more than one turn of service; they drop several balls when removed.  The axle keys don't wear out as such, but many are weak (it's a crap design, with the hole taking up most of the width) and a clumsy change when stopped can snap them.

Does the hub used on the Brompton differ from a good old Torpedo? I always thought of them as pretty reliable  ???  If they're that bad should I be selling my 1980's retrobrake Torpedo to a Brompton fan for spares rather than using it?

rogerzilla

  • When n+1 gets out of hand
Re: Brompton Sachs/SRAM 3 Speed Hub and sprocket Set
« Reply #9 on: 06 November, 2022, 09:38:14 am »
It's a Torpedo Spectro T3. Reliable enough except for the snappy axle key, but not as well sealed as a SA hub.  I overhauled one last year and used the very last of my SRAM IGH grease (also no longer made).
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.