Buy bicycles in Vientiane or Luang Prabang

I was at two different bicycle shops close to each other in Vientiane, this January. Both of them were just a few of blocks South of the Thai Consulate. One of those shops is managed by a French(?) guy, and the other by a Lao man.
We had our bikes already and mostly just needed some accessories. We did not feel particularly welcome at the Falang shop and so found the other one. I bought a helmet, sunglasses and a cyclist shirt there. Good stuff, nice dude and OK prices.

The second time we were there the Falang from the other shop came in. Seems he shops there as well.
Sorry I did not take note of the name and address. It could be the Chongchareon Bicycle Shop 337 Dongpalan Rd, but I am not entirely sure.

Anyway that shop sell good bikes at decent prices, Trek and Merida among others.

Try Laos yellow pages....
http://laoyp.com/categories/la10428-bicycle-sales-services/listings

I suspect you will get a better deal than in Thailand as they don't seem to have the same ridiculous protectionist import duties.
however across the river a bit in Udon Thani you'll find a LOT of outdoor sports goods....far more than you'd expect to see in a town like that - I guess it's driven by being on the backpack trail and so close to the border.

Lot of good cycle routes around LP, I guess there will be bikes for sale there as there are so many for hire......
Make sure you buy Hobo Maps for the places you visit in Laos......special bike routes marked out.

What price not are looking at when saying not expensive?

Some of the cheapest will be Chinese single speed ones - not perfect for Laos with all the mountains in the north, but you can load it on a bus for real mountainous parts.

Size will be next problem, if you are tall that is. Plus you will need some way to put your stuff on it.

And remember August is the heigth of the rainy season - so be prepared to get wet.

I bought an Asama single gear 24 inch bicycle in LP last year for about $115 US and it's a great solid bike. Been taking it on trips around Laos by putting it on buses between towns, no problem at all for about half the cost of my bus ticket extra. They have them for sale in Vang Vieng and Vientiane also. Should be easier to sell a bike like this than a more expensive model as the bike rental shops in LP, L. Namtha and VV also have them for rent.

As Albin says the best 2 bike shops in Laos are on Dongpalan Rd (the french guy shop) and close by on Phonthan Rd (Chongchareon). This section of Phonthan Rd often gets called Dongpalan Rd.
The french shop (almost opposite Logos Academy) has some second hand bikes too and will do a full service for you if needed.
The Chongchareon shop has some lower end Specialized & Trek bikes - about $400 - which would suit your purposes.

There are many places selling the brightly coloured single speed bikes popular with teenagers now, but these will be no good for you. There are plenty cheap chinese bikes too, but I wouldn't want to attempt to tour on one.

If $400 is too much for you then why not bring in a decent secondhand one with you? I often travel with my bike and it is never difficult.

this topic is interresting to me also: I am actually in Luan Namtha and investigating to buy a bike to go down to Luan Prabanh and Vientiane. I have to be back on the plane by june 23.
For now all I was able to find is a 2nd hand old Chinese 100cc for 2.5 million kip or a 2nd hand chinese but not so old for 4 million kip. Obviously I dont have 4m kip but I am afraid that the other one can break down.
Is this the right prices? I hear Honda is much better but they tell me ismore expensive... am I beeing ripped off?

good luck on your investigation

You can buy a brand new Chinese 100cc (Yincin or similar) for 4 million kip ($500). For a decent second hand one you should be looking at around 2.5million kip

New Chinese ones cost between $500-800 depending on make/brand. A new Honda Wave is about $1200 for the basic model. If the cheaper one you are looking at rides OK and the engine sounds OK, gearbox smooth enough, then have one of the many motorbike garages in Namtha check it out for you - it won't be expensive. At least then you can have some certainty that it won't seize 5 minutes after paying for it.

The Chinese bikes get a bad rap, but some of them are pretty good these days. We had a Yincin for 7 years before giving it to a relative and it rode well, even on a long trip Vientiane - Pakse.