Bicycles are required in many missions, and you are expected to provide the bike if it is needed. So finding a reliable trustworthy source for a bike ahead of time is going to be a lot easier than trying to find a good bike at the last minute.
The best way to get a missionary connected with what could become his primary transportation - his bike - is to make sure he is involved in the selection process. When parents select and buy the bike, and the missionary doesn't participate, it often leads to indifference about proper care of the bike.
Many issues are involved when selecting a bike. Every mission requiring bikes will expect the bike package to include a helmet, lights and a lock. In addition, a water bottle, fenders, tool kit, kickstand, and pants strap are essential items.
The right style in today's world of bikes is what is known as a hard-tail mountain bike. This is a bike that has a front shock absorber, a stout frame, a good set of gears and brakes, and is easily adjustable to fit the missionary.
Bikes such as cruisers, dual suspension bikes, or racing/road bikes all lack the essential designs and equipment and features a missionary will require.
Never, ever buy the fanciest bike you can. There is no reason to pay too much for a bike that will be involved in the utility riding a missionary will do.
On the other hand, don't waste your money on cheap bikes such as discount store bikes. They will break and can cause severe accidents.
Right now there is a lot of talk about disc brakes on bikes. Although they generally work well, they are expensive and are troublesome to maintain. Missionaries ride in a lot of less-than-desirable situations where road debris can get caught in their wheels. When this happens with a disc brake bike, it will usually end up in the shop with rotor and caliper repair issues. Good quality V-brakes work very well and are much less expensive to buy and maintain.
Make sure the bike you buy will be properly assembled and ready to ride. A missionary isn't going to have the time or possibly the talent to assemble a factory-boxed bike.
Don't forget that the bike has to be sent to the mission office, and that means shipping costs, unless your source pays the freight.
Some missions have local sources for bikes, but they don't always offer all of the needed accessories or extend the warranty to cover the full period of the mission. Also, they usually never offer a theft replacement program.
Buying a bike from your local bike shop is like having your plumber select your next car for you. Very often bike shops do not have a clue about the kind of riding missionaries do, and they are prone to sell too-expensive bikes and extra equipment missionaries just don't need.
Most quality bikes have a manufacturer's warranty for only a year, which is half the time of the mission. Find a source that will warrant the bike for the full 2 years of the mission.
Inquire whether or not the source you buy from will offer service after the sale. There should be a way for the missionary to contact the bike provider if there is a problem with the bike any time through the course of the mission.
Most importantly, make sure there is a practical, inexpensive, no-hassle program provided by the source to replace stolen or accident-destroyed bikes. There is a major issue of bike theft in most missions, and local police often offer very little encouragement or help in retrieving stolen bikes.
Never select a cable lock for a bike. They are easily defeated with side cutters or a hacksaw. The most secure lock is a quality U-lock.
Make sure the missionary understands the extensive possibility of the bike being stolen. Missionaries who come from areas concentrated with LDS population are often naive about the cunning, clever thieves that inhabit most cities. There is no such thing as a safe time to leave a bike alone unlocked, even for a moment.
Make the missionary aware of the importance of proper and regular maintenance on the bike. Many missionaries have very little experience with mechanical things and tend to overlook needed maintenance. When that happens, the bike can break and the investment cost escalates.
When it comes time to send the bike home, if it isn't going to be used when it gets there, consider donating it to a resource that will rehabilitate it and provide it to needy people for transportation.