Phraya Lithai Moutain bike competition
When : 11-12 April 2008
Where : Si Satchanalai History Park and Phaya Li Thai monument A.Si Satchanalai Sukhothai province
Register : Phaya Li Thai Monument

1. Mountain bike ride on normal road
    On 11 April 2008. Start 10.30
    Distance : 60 kms 20km per loop
    300 Baht to entry

Age.
1.1 Any age for woman
1.2 Man under 16
1.3 Man 16-18
1.4 Man 30-39
1.5 Man 40-49
1.6 Man 50 up

2. Cross country A
    On 12 April 2008. Start 13.00
    Distance : 40 kms 
    350 Baht to entry

Age.
2.1 Any age for Woman
2.2 Any age for Man
2.3 Man under 18
2.4 Man 30-39
2.5 Man 40-49
2.6 Man 50 up

3. Cross country B
    On 12 April 2008. Start 11.00
    Distance : 25 kms
    300 Baht to entry

Age.
3.1 Any age for Woman
3.2 Woman 35 up
3.3 Man under 15
3.4 Man 30-39
3.5 Man 40-49
3.6 Man 50 up

4. Cross country C
    On 12 April 2008. Start 10.00
    Distance : 10 kms
    100 Baht to entry

Age.
4.1 Girl under 12
4.2 Boy under 12

5. VIP Competition
Distance 25 km Both man and woman at any age can be in.
1000 Baht for entry

Recommendation's competition for foreigner is Cross country B and Normal road.

Here are the details in thai >>> http://thaimtb.com/news/160344-5.html

Some more details in english:

1-Frame : The participate bike must be the MTB frame only
2-Tyres size : 26inch with (I'm not sure this is the exact translation since I'm not familiar with MTB terms., pls wait for confirmation from other reply or ask you friend)
3-Front tyres thickness at 1.8 thickness and above
4-No aero-bar
5-All bike need to be inspected by the race committee
For more info, pls contact the organizer at 0894610256