hi. thank you for a moment of your time. i acquired a bianchi megalite steel cross bike, with a stem and quill style fork. took it off road, on a steep downhill, the fork seemed to fold under and the wheel went one way and the handlebars went another. got up, straigthened and tightened the thing. another slick downhill, did it again. i had a redline with a newer threadless fork, never did this. is this too much for an older style fork? is it hard to convert to a new fork? what is involved in the changover? i appreciate the advise.