This is difficult question, but I will answer to you correctly and precisely coz I love to answer most difficult questions only.

You can go to villagio and there you will find a shop in between the malls made of glass selling mercedez branded
caps, toy cars, watches etc. They deal exclusively the product modale of Mercedes and they sell genuine portable bycicle costing 10,000/- and you may get it by negotiation at the price of 8000/- which can be carried for travelling and can be used like any normal bicycle.

There is no other place in Qatar who sell this kind of product.

Hope I guided you to the right place to meet your nice demand. Good luck.