Spotlight on the rear sprocket


Jammed sprocket

Megan Lynch, Sep 1997:
I noticed that the thin aluminum ring that separates the back chainring from the hub had gotten bent. In fact, it had gotten severely bent. The chain had actually gotten back onto the chainring again, but it had a third of the aluminum ring between it and the chainring!

Replacement rear sprockets



Turning a 5 speed into a 10 speed

John, Jan 2004:
Further to my previous postings regarding conversion of Sachs 3 speed to Sturmey Archer 5 speed with two sprockets to make 10. I have done it. It works.
Ingrediants required.
How to do it.
Take a 15 or 16 tooth Shimano cassette ring and mark three lugs which match the Sturmey Archer sprocket tabs. File away all the others. File to make fit the S/A hub (the) three remaining tabs. Fit to S/A hub. Remove the FIRST cog (it must be the first. This will be a 13 tooth. File down the tabs as mentioned above-much harder as this sprocket is hardened. Fit to hub. Now make sure the chain which must be a narrow deraileur type fits OK. Now fit the wheel into the Sachs Brompton. Fit 5 speed lever, set up as usual. Now make sure the dual cog shifter shifts correctly-if not adjust as per Brompton instructions. Hey presto a 10 speed Brompton without the need for a front changer and dual chainrings. Gear ratios now are:- 35-40-42-48-53-61-67-77-79-92. Congratulate yourself for all your hard work.

Pictures to show the finished item are here Look at 'Latest pictures section'.

Is it normal that the sprocket looks loose and wobbles?

Rear derailleurs