How Do I Jump With The Bicycle Pokemon Pearl In Pokemon Diamond, How Do You Jump On Those Bicycle Rocks?

In Pokemon Diamond, how do you jump on those bicycle rocks? - how do i jump with the bicycle pokemon pearl

I know it's a stupid question, but I am in desperate need, earthquake of TM in the secret entrance to the cave get under the cycling road. I'm already here, but how can jump over the rocks with the bike? Please tell me which buttons to press ... Thank you guys ....~