I got an fat tire ebike. My non shock front fork bent on it so i replaced it with a fork that had shocks on it. Installed it all good and even ordered a new top cap (fork needed the top cap installed too) put everything together and tighted the top cap, straightened the headset and lined it up. Tightened all the bolts and took it for a test drive. First thing i noticed the handlebars kept on wanting to sway left and right. When i pick up speed the bike doesnt want to ride straight. Feels like walking a strong dog that just pulls you. Just doesnt feel balance no matter how much i adjust the headaet.
Worth reading up on rake (AKA offset), trail and head tube angle. Pictures of old and new fork and front end of bike would help, if not, makes and models of bike and new fork.– mattnzAug 15, 2022 at 20:27
The aostirmotor s07 p for the bike. And the new fork was the bucklos 25in x4 i found on amazon. After messuring my self the new fork added 4 extra inches to the bikes height. I couldnt figure out how to add pics– Thomas McCafferyAug 16, 2022 at 0:51
From pic on internet, the old fork had a much smaller offset compared to the new fork . This has decreased trail, making the bike less stable. You could try an angled headset to decease steerer angle to compensate (e.g. Wofllink geoshift or Cane Creek Angleset) bikeradar.com/features/…– mattnzAug 16, 2022 at 2:58
One of two possible differences can explain the issue.
The most likely is that putting in the new fork affected the handling geometry. For example, if your old fork was non-suspension fork, it could be that the axle-to-crown distance is short. If you put a new fork with more axle-to-crown distance, the front end of the bike rises. Also forks may have differing amounts of rake. These two differences, difference in rake or difference in axle-to-crown distance could affect the handling of the bike.
A second possibility is if you have a Surly Pugsley, one of the earliest fatbikes (unlikely). It has an off-center rear wheel. They decided specifically to make front and rear wheel interchangeable so the front wheel too has the same 135mm over locknut distance and also the same offset built into it. If you put a non-asymmetric fork in there, it could mean the front tire is no longer centered in the frame due to new fork being non-asymmetric, meaning the bike doesn't want to go straight. However, this is a very unlikely case because you would need to find a non-asymmetric 135mm wide front fork -- where would you find one?
So most likely i will need to get a normal fork. The new fork is higher up then the old fork. Think it raised the height 2 to 3 inches. Aug 15, 2022 at 19:49