Bike Friday User Group UK

Technical Support - Gears

Important Notice

Information is given here in good faith, but no one should carry out any work on any bicycle unless they are competent to judge for themselves that the action proposed is safe, nor should they attempt such work unless they have sufficient experience and the necessary equipment to complete the work safely. The compilers of this information, the UK User Group, the UK distributors, and Green Gear cannot be held responsible for the actions of those who read these pages, or any results of those actions.

Most Bike Fridays now seem to be fitted as standard with the Sachs 3x7 gear system, which combines a 7-speed derailleur with a 3-speed hub gear. Some models use a derailleur only system, with multiple chainwheels, and the new StationMaster model is listed as having only a 3-speed hub gear.

The adjustment of hub gears and of derailleur gears is widely documented in bicycle maintenance books, magazines etc, and we do not propose to go into detail here. Some information on the Sachs 3x7 system was given in the Volume 5, Number 2, July 1997 issue of Foldable Flyer, and you can also find information on the Bike Friday web site. Another very useful source of information on the adjustment and maintenance of gears in general, including the Sachs 3x7, is the Masterclass article written by Hilary Stone for The Moultoneer, the magazine of The Moulton Bicycle Club. The article appeared in 2 parts in issues 52 and 53 of The Moultoneer, and the text (but not the photographs) is also available on web pages.

Gear cable One point not always mentioned when articles appear on adjusting the Sachs 3x7 is that some people are using Shimano STI levers, or RapidFire levers, to change the hub gear. These levers are intended for use with derailleurs, and the left hand one would therefore handle selection of the chainwheel. The cable movement which this lever gives is not really correct for the hub of the 3x7, but as users will know, it will in fact work the hub satisfactorily. However, to get it to do this means that you need to be careful with the adjustment. The best way of setting it seems to be to adjust it so that you can only just get into bottom gear, with the cable very tight. When middle gear is selected, the cable almost goes slack, but just holds the hub in the middle gear, while in top gear the cable is very, very slack (see photo). You should also try back-pedalling in each gear - if the rod and chain jerk, and you cannot back pedal freely, try adjusting the cable by one click. Fine tuning may be a matter of trial and error! Once set up, though, you will probably not need to make any adjustments until you next remove the rod and chain for lubrication, or need to remove the wheel to replace a tube.

A rather obscure problem I encountered a couple of years ago with a Shimano indexed derailleur gear was that the gear selection became unreliable, and despite repeated attempts to adjust the setting, the system would not perform satisfactorily. In the end I found a small split in the plastic outer of the cable. Once this cable was replaced the system performed perfectly again. It seems that the indexed system is very intolerant of any give in the cable outer, so make sure that when replacing cables on these indexed systems you get proper cables intended for indexed systems - the outers are much stiffer than old non-indexed ones - and that you do not have any damage on the cable - even the plastic outer, which contributes to the integrity of the system.

Additional information

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