But it is hard to use on mobile phone. I looked it for tapatalk but I think bitcointalk isn't there. Do you know any practical way of using bitcointalk with mobile?
Unfortunately there's no safe and practical way to use this forum on mobile phone.
There were 3rd party attempts for such apps but they are a security risk - you give your credentials to an app you don't know what it does with your data. And bitcointalk accounts are valuable.
There's also the wap mode for surfing this forum, but imho it's not convenient enough. However, you can start with
https://bitcointalk.org/?;wap