[Classic Bikes]

I am in the process of building a custom made mountain bike patterned after the BMX bike I had growing up. My question is what effect would it have to use the same frame angles on the bike I had growing up with an 18" mountain bike?

Head Angle: 74.5
Seat Angle: 72.5

Thank you very much for your time.

 

[jkuo]

The seat angle is pretty close to the 73 degrees a lot of mountain bikes already have. But a 74.5 degree head angle is going to result in a very twitchy ride. I remember that back in the day, all my cross country bikes had 71 degree head angles. Nowadays, it seems as if slacker angles are normal, I'm seeing 70 and 69 for some bikes.

I am in the process of building a custom made mountain bike patterned after the BMX bike I had growing up. My question is what effect would it have to use the same frame angles on the bike I had growing up with an 18" mountain bike?

Head Angle: 74.5
Seat Angle: 72.5

Thank you very much for your time.

 

[Mel Erickson]

That head angle is way too steep for a mountain bike. You won't like the handling. Do some research before establishing your angles. Copy the angles on a mountain bike that handles the way you want. I sure wouldn't base mountain bike frame angles on a BMX frame. Two totally different purposes. Hop on over to MTBR.com and go to the Bike and Frame or Frame Building forums.

 

[tarwheel2]

Have you talked to the frame builder? Any decent custom frame maker should be able to answer your questions.

 

[Mel Erickson]

Have you talked to the frame builder? Any decent custom frame maker should be able to answer your questions.

I got the idea he was building this himself?

 

[Peter P.]

You better discuss it with a builder who's experienced with mountain bikes. NOBODY builds mountain bikes with a 74.5 degree head angle. You'd be hard pressed to find a road bike with that head angle, too.

 

[Classic Bikes]

Thank you for all of the responses. I think I am going with a the modern geometry on my vintage custom mountain bike.

Head Angle: 71
Seat Angle: 73

I want my bike to have a vintage look however, I want it to have more of a modern ride.

 

[BentChainring]

Head tube angle coupled with fork-rake affects bike handling and 'feel'.

You can compensate for a funny head tube angle with different fork offset's... Too tired to run the calculations right now, but yah. Seat-Tube angle can affect lateral stiffness with deviating from more vertical seat tube angles.