Horse who wont slow down

Hi I have a rocky 12 yr old gelding who is perfect in everyway except when riding exspecially with other horses he wants to go like a bat out of hell, and when he is with others he walks sideways and flips around fast to face backwards wether or not theres other horses there or not, I tried circles and one rien stops but its hard to do it all the time with other riders. How can I get him to relax and walk out, he is rough as a cow????????????? I have only ridden him about 10 times, he is a new rescue purchase.

Hello,
I would go back to basics and get your foundation training good with him first. Build a relationship with him and gain his trust. Then start riding him in the arena with other horses and get him used to this first. Once he is comfortable with other horses in an arena then take him out on a trail that he knows and feels comfortable doing with other horses. This is not just about his gait speed this is about his confidence and relaxation. Once you get him confident and relaxed his speed will slow down, and also getting your foundation training better in an arena will really help you out on the trail.
Thanks,

I have no arena but his ground manners are excellent and does everything I ask of him during ground and round pen work. Does not like crowds of horses or things behind him, He whips around when things behind him bother him but he has never spooked on the trail, its wierd. Just want him to slow down and walk and slow his gait are there things I can do to slow him down when riding besides one rien stops??

Hello,
Yes circles slow fast horses down and straight lines speed slow horses up. So if you are going along and want your horse to slow down but not stop try to just check him with your reins to slow him down if this does not work turn him in a circle (does not have to be small but not huge either, like a 20') and keep him on the circle until he is going the speed you want and then let him come out of the circle and continue on your straight line, if he gets fast again check him, if that does not work take him in a circle. Repeat as many times as needed until he starts listening to your checking his speed and gets soft and relaxed.
Hope this helps,
Thanks,
Chelsie