How do I make trains which fit LEGO rails (6 studs)?

Question

Christmas is coming and my son (7) is asking for trains.

I was planning to buy a set, but they are expensive, and I think it is a bit too advanced for my son.

Therefore I decided to buy a box of rails (just rails) as well as LEGO pieces. I think we would not have a problem with the top parts of trains (we have plenty of LEGO bricks at home), but I am not sure which wheels to buy.

Do you have any recommendations? We have a couple of train wheels. Will any LEGO train wheels work for the rails?

I have wheels from this Classic set:

Answer 1

The most common train wheels (2878) look like this:

These may be available directly from LEGO via online Pick-a-Brick or Bricks and Pieces, but it is probably easiest and cheapest to get them used on Bricklink.

If you want something cheaper, you could go with the small track-compatible wheels (50254):

That part is available very cheaply on Bricklink. These have been used in many sets, often having nothing to do with trains, but you can see how they are used to run on track in Rail and Road Service Truck (4541):

Those small wheels obviously wouldn't look great on a full scale LEGO train, but you might be able to put something together that looks alright at a somewhat smaller scale.

Answer 2

That set comes with wheel holders, that place the wheels for rails 4 studs wide, i.e not suitable for LEGO tracks.

Unfortunately I can't find any non-train sets containing parts suitable for LEGO tracks, but at the moment you should be able to buy the newest edition of the Hogwarts express (set #75955), that is at least not motorised or comes with tracks, so you don't pay for either. It's still not cheap though.

Answer 3

LEGO trains come with special wheels, wheel-bases and magnetic connectors that are only available with LEGO train sets. While you might be able to cobble together something that sort of works, there is no substitute for the actual train parts.

The train wheels are designed in such a way that they can run smoothly on both curved and straight LEGO train tracks. If you study their shapes, you will see that they are actually quite complex. Train wheels are connected with small metal rods, instead of LEGO Technic axles, to assure a very smooth ride over the tracks. The special wheel-bases are designed to accommodate the wheels and metal axles, and are just the right length to be able to handle curved tracks. And the magnetic connectors allow easy coupling of the train cars.

While some LEGO car wheels have grooves, they are not designed to fit on LEGO train tracks. Some can sort of perch on top of the rails, but they are wobbly, and will run off the tracks easily, especially on curves.

If you would like to get into LEGO trains, I recommend getting an actual LEGO train set to avoid all the hassle and frustration of trying to build something from parts that are not meant for trains. Just get the cheapest LEGO train you can find. It will give you all the parts you need to build a train, and you can always customize the engine and cars from parts you already have.

Currently, the cheapest LEGO train is the #75955 Hogwarts Express for $80. However, you can often find better prices on eBay for used LEGO trains or partial sets with only the train but no extra parts and minifigures. Also check Amazon during the holiday shopping season. They usually discount older LEGO trains by 20-30%.