Headtube angle help

peng said:

I'm getting a Sintesi moab frame soon and it has a very slack headtube angle of 68 degrees which i find rather misfitting for a XC racing frame. Anyway, i was thinking of putting a shorter stem (about 70-80mm) to negate the sloppy steering. Would this work??

Keep in mind that the frame interacts with the fork. Headtube angle will effectively change if the length of the fork you're using isn't the same as the one the frame was intended for. The geometry of the naked frame is less important than the geometry of the assembled bike.
IMO stem length is more influential to riding position than steering response.

68 degrees is pretty laid back, very out of place on a XC frame these days. Way back Fat Chance put out a frame that was touted to be for XC'ish use that had a 69 degree head angle, which was weird even back then.

Going from a 71 degree head angle, you are going to notice a big hit when riding slower more technical areas, you are going to find your front wheel will have a tendancy to wander. On the other hand, the faster you start to go down hill, the more stable the steering will feel.

The previous poster is right, a stem will not correct this. Chances are that frame has a fork that is just too long for it. Raising the front end reduces the angles. Since I cannot think of a single manufacturer that has a 68 degree headtube angle on an XC bike, it has to be the fork. Find a fork that is a better match for the frame and you will bring your frame back into proper geometry.

Cheers,
Juba

from where to were exactly you measure the angle?

zaku said:

from where to were exactly you measure the angle?

If your bike is on a perfectly flat and perfectly level surface, it is the angle your headtube is at compared to the floor.

To measure your headtube angle, put your bike on a flat and level surface. Get a carpenter's level and an angle finder (angle finders even come in digital readouts these days). Put one edge of the angle finder along the outside of your headtube. Hold the level near the top of your headtube, and put the other edge of your angle finder along the level. Then pivot the level in your hand until it is perfectly level, and you will get the measurement of your headtube angle. Same method for measuring your seat tube angle.

Cheers,
Juba