Some time it happens that the piles is regressed so much that on examination it is difficult to find that bulging. This presentation is making sense for piles only which may not be very severe and only happens when you are driving bike, because of the stress
associated with the driving.
Try to observe if this is the condition during defecation also, as during defecation, there is pressure and if the bulging is comming at the time of defecation , than chances of piles is there and need to work up accordingly.
The chances of fissure is rare as fissure is most of the time present as a very painful condition and have bleeding also.
You can have investigation to check the pressure changes in the anal area to make sure the muscular sysytem there is working fine.
Thanks and hope this will help.