How many flexible tracks does it take to make a complete oval?

Question

I have couple of straight tracks, no curved tracks, so the only option now from me is to buy the new 7499 straight + flexible tracks. Therefore:

How many boxes of 7499 tracks do I need to make a complete oval circuit?

There are reviews but none of the is actually mentioning this. No pictures either.

Answer 1

Each piece of flex track is equivalent to 1/4 piece of regular track. The standard train curves are 1/16th of a circle and thus an oval shape is not possible, however, with 64 pieces of flex track you could make an oval by squashing the circle a bit. 7499 comes with 16 flexible tracks, so you'll need 4 of them to make a regular train circle.

The flex track can be used to make a smaller circle than the regular track:

but as TheBrickBlogger pointed out, the flex track has performance issues and such a tight circle will be difficult for your trains to navigate. The trains tend to fall off if conditions are not perfect. Over Christmas I built a large layout under my Christmas tree and I had to remove all the flex track in order to prevent derailing. Part of that was due to my train design, part of it was due to the fact that the track was sitting on a mix of carpet and hardwood flooring, but part of it was that the train is very sensitive to bumps in the track and flex track exacerbated those issues. Depending on your engine design you might have more or fewer issues. If you are just pushing the train by hand, it will probably be fine.

Also keep in mind that the standard lego train car with fixed (not swiveling) wheels can only navigate a certain minimum radius. Lego puts the wheels 10 studs apart so that they can just barely make it around the fixed curves. If you build the small flex circle, or squash a 64-flex-track circle into an oval, your tightest curves will for sure be too tight for those cars to navigate.

Normally Lego sells curved track in an expansion kit. It seems that right now (May 2015) the only kit is the 7895 Switching track kit. That kit comes with 4 curved rails and so you'd need to buy 4 of them to make a circle. If that's not your ideal choice of parts, then Bricklink would be best. Or, use this as an excuse to buy a whole train kit, which comes with track, train cars, motors, etc. You can never have too much Lego.

Answer 2

The flexible tracks are not designed to make a full oval, but to add subtle, smaller curves in a train layout, using just a few at a time. If you do use too many flexible tracks next to each other they will slow down your train, they are very noisy, and can even derail the train. Here is an excellent comparison video between the regular curved tracks and the flexible tracks: http://youtu.be/fGcD_QtOcRQ

If you would like to create a full oval I would suggest that you just get the curved train-tracks on BrickLink as they are currently not available directly from LEGO (except in full train sets). They are about 50 cents each and will be much better for your purpose. You will need 16 of them to make a full circle: http://www.bricklink.com/catalogPG.asp?P=53400&colorID=85

Answer 3

To add to the excellent answers already provided, the cheapest LEGO train set currently available giving you a full oval/circle is 60051 and costs $149.99 in the US Lego store. You might be able to find it slightly cheaper on Amazon.com (currently $127.21 in the US) or ToysRus.com (currently $149.99 so same as LEGO store) sometimes.

The equivalent purchase of 4x 7895 Switching Track is $15.99 in the US Lego Store for each set, so a total of $63.96 for 4.

If you go by absolute price, the 4x7895 is your best option, and you get 8 switches extra, which you could use once you expand your track, or sell back through bricklink or eBay (current US selling price on bricklink is around $3 per switch track) which would reduce the total price by $24, giving you a total price of roughly $40 for the oval.

The 60051 train set does come with batterybox, trainmotor, IR set etc, plus many pieces. The value of that set is probably better than 7895 gives, at a roughly $100 premium over 4x7895 with sellback via Bricklink/eBay etc.

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Separately, there are 2 more options you can consider:

1. ME Models sells LEGO curve sets with bigger radius than the standard R40 LEGO curves. Their R56 curve pack costs $19 for a half-circle (so $38 for a full circle) plus shipping. They have several other radia as well, but those will cost more. From what I've read the fit with "normal" LEGO is very good and train enthusiasts love these rails.
2. If you don't mind the extra pieces, you can make curves out of straight rails by using this technique (youtube) . The train's movement will be a little jerky but otherwise it works well. You'll just need a lot of space as the radius of such an oval is very large. But most LUGs use this technique in their train layouts, so it is "endorsed by professionals". Basically, you offset the outside joint by half a stud every rail using a 1x3 and a 1x2 jumper. The upside is that you can use this technique to make the outside of the curve 1 plate higher than the inside of the curve to allow your train to "bend" through the curve just like trains in real-life do.