|Friday, 21 October 2005|
Strong wheels are especially important on a tandem.
If you are both light (i.e. 9 stone or less), do not go in for heavy touring or off-road and use good quality components built to the highest standards, then 36 spoke wheels will do. If you are more normal then 40 or 48 spokes are recommended.
The 26" mountain bike size wheels are much stronger than the 27" or 700C size normally found on solo bicycles, and providing tyres without large knobbles are chosen do not present much additional rolling resistance.
Use the strongest rims you can afford, and choose a rear hub which positions the rim as near to the centre of the hub flanges as possible to even out spoke tensions. This generally means having a wide hub - 140mm or greater between the frame dropouts. Before you buy, ensure that the hub matches your frame dropout width. If not see a reputable framebuilder who can give advice on re-spacing the dropouts. On no account fit a hub that is too wide for the frame as a fatigue failure will shortly follow.
Shimano now manufacture special tandem hubs with wide drop out widths, 40 and 48 spoke holes and freehub cassette bodies. The rear hub is threaded to accept a rear drag brake. The freehub cassette design allows the bearings to be positioned closer to the drop-outs, significantly reducing the loads on the bearings and extending the life. The common problem of bent axles is also eliminated. They are too new for any meaningful feedback on performance.
Hope also manufacture tandem hubs. These hubs can be specified to accept disk brakes so are a popular choice. The bearing design is not as good as Shimano, and there are reports of cassette body failures.
All tandems, except those used exclusively for racing, should be fitted with three brakes. The main brakes are operated by the Steerer while the drag brake is operated by the Stoker.
The traditional solution is to use long arm cantilever brakes operating on the front and rear rims, with a drum drag brake on the rear hub. A more modern option is to use the V brake design, again with a drag brake. The V brake provides excellent braking, however special adapters are required if drop handlebars are selected.
Hydraulic rim brakes are available and also offer excellent performance.
Rim brakes have several disadvantages
For this reason disk brakes are becoming more common, with an additional cantilever or V brake as a back up. Disk brakes do have the significant disadvantage of requiring special hubs and having the forks and frame suitably designed. Mechanical and hydraulic systems are available. Hydraulic systems are generally considered superior to the cable operated systems, however most are designed for use on MTB handlebars and require special adaptors for use with drop bars.
Warning: Do not fit a front disk brake unless the forks have been designed for the increased stresses!
Gears are especially important on tandems as the range of speeds is greater. Standing on the pedals to climb hills is certainly possible but requires practice and close co-ordination between the riders, so low gears are essential, while on a long descent speeds of 50mph or more are not uncommon!
Most tandems are fitted with a triple chainset to provide the necessary range of gears without too great a gap between gears. It is better to go for low ratio gears (i.e. larger sprockets at the rear, smaller chainrings at the front) rather than high ratios - you can always freewheel down a hill! Larger sprockets and chainrings give significantly improved efficiency and life over small ones. Sachs equipment seems to last longer than lower end Shimano, though XT and XTR equipment is not bad.
The modern indexed systems are a real boon, especially those with the controls on the handlebars. Some care has to be taken with drop handlebars to ensure that the brake cable movement is suitable for the brakes, which are normally designed for MTB use.
This page last updated 08/07/04
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