aaronM46

You can follow my build at https://www.bikeforums.net/bicycle-m...ld-thread.html

Now that I have it built it is crazy sensitive to steering inputs. Almost scary to ride. Not much on the geometry has changed other than the front fork, but that was minimal.

rsbob 

Sounds like something in the headset needs some real tightening.

aaronM46

It is tight but the geometry seems off and I do not know why.

rsbob 

Too steep a fork? The closer to vertical, the twitchier the steering.

aaronM46

Quite possibly. It is a new fork. Is there any way to fix it without replacing the fork?

noimagination

Are you sure that it isn't you?

I have two bikes, one is a touring bike and the other is a "racier" geometry. When I ride the "racy" bike after a bunch of time on the touring bike, the "racy" bike feels very twitchy. It takes a while to get used to the racier bike again.

Sorry, I'm not knowledgeable enough about bike geometry to give advice about forks.

shelbyfv

Not surprised....

bboy314

I’d start by comparing the axle-to-crown measurement on the old and new forks.

freeranger

Here's a link that might help, lots of things to consider when replacing a fork (and go thru the Related Pages at the btm of the page): Fork Length - Bike Insights

nomadmax 

I guess all those number DO mean something.

Fork rake
Axle to crown distance
Head tube angle
Overall diameter wheel diameter

Education costs money, especially after you need it.

BlazingPedals

I browsed through the thread and didn't see a pic of the bike with the new fork on it. I think that RSBob hit on it - you installed an incorrect fork, one that dropped the head tube and consequently made the steering angle steeper. Since you started with a suspension fork, you need a fork that maintains your steerer tube at its former height. Is it possible to add an inch or two of spacer between the crown and steerer tube? If not, it's new fork time.

Rogerogeroge

Until I see a pic of the complete build, I’m going with the theory that the fork was installed backwards.

Iride01 

I don't know that there was a picture of the finished product. So how are we to even guess what might be up. Although if nothing is loose and wobbly, then the fork being on backwards might be a good thing to check.

I suppose it's possible that you may have gotten a fork that the rake and your head tube angle just won't work right together. But I also wonder it it's just that you aren't use to sporty handling. What previous bikes do you ride that you are comparing this steering to?

Ironfish653

Going by the build thread; OP replaced a suspension fork on his Schwinn hybrid with what I think is a "standard" road disk fork (not suspension -corrected). There was also a change in handlebars / stem as well.
Could totally result in significant changes in geometry/ handling; esp since the spirit of the build was " A Frame is a Frame, and a Part is a Part, and I'm not going to let the naysayers get in my way "

3alarmer 

.
... that bike took a lot of abuse in the build thread. I can see where it might be sensitive at this point.

79pmooney

This sounds like a trail issue. Trail is the distance between where an extension of the headtube would hit the road and the point on the road directly under the hub. It can be both observed and calculated. The further the point below the hub is behind the head tube extension point, the more stable the handling.

Another factor that affects perceived "twitchiness" is how far your hands are in front of the headtube/steerer centerline. The further, the more stable. You have a short stem and near straight handlebars that are in fact swept back a little so your hands are maybe 3" forward of that centerline.

Measure or calculate your trail. (And get it right; small differences between trails make a big difference in handling. 45 to 55 mm covers most of the bikes out there.) Until you know the trail, you are just trying to shoot pigeons in a dark barn. (Yes, rule out loose/tight headsets and other mechanical issues.)

79pmooney

I just wrote a serious post, posted and read this. TG I wasn't drinking coffee. It'd be up my nose.

smd4

I'm going with the new fork changed the front-end geometry.

friday1970

Put that bike through USMC boot camp. I will come out less sensitive, even maybe a darker sense of humor.

79pmooney

But it might not respond to commands from someone it doesn't perceive as an officer.

Maelochs

The guy put a shorter, steeper fork on hi8s bike and is surprised that now it responds like it has a shorter, steeper fork.

Kudos for having the courage to try, but in matters where you might end up eating pavement, it is good to do a little research first.

rollagain

Can't be; he's got disc brakes on it. Think about it for a minute, it'll come to you.

aaronM46

Here are some pictures:

aaronM46

smd4

Compared to the stock photo of your bike posted in the first post of the rebuild thread, I'm still going with "shorter fork." I'd also angle those bars back a bit (make them "flat"), if it were mine.

Kudos for rebuilding it. Maybe you'll get used to the ride.