Hi Vinothkumar,

Thanks for your post. At this time, we limit group challenges to 25 participants. You can read more about group challenges here.
 
However, If you are interested in hosting a global challenge on Strava, sponsored challenges are available to relevant sporting/athletic brands as a paid media activation. You can find more info here. 

UPDATE: We are pleased to announce that creators of Group Challenges may now invite up to 199 athletes that follow them on Strava. In order for an athlete to join the challenge, they must be a subscriber, have a free subscription trial, or have free challenges left. Creators can also allow other athletes in the challenge to invite athletes who follow them. From the challenge details screen, tap the three ellipses [...] in the top right to open the challenge settings, and then enable the toggle that reads “Allow Participants to Invite Others”. For more info on Group Challenges, check out this page. 

UPDATE ON GROUP CHALLENGES: Starting in August 2024, only Strava subscribers or users with a free trial will be able to create a group challenge, find out more here.