Effect of lowering boom on steering tube?

Kenneth

Well-Known Member
I've been browsing the forum and was reading about lowering the boom on the fork steering tube.
Other than bike fit does this have any benefit in handling or power transfer ? I'm just fiddling around with the S40 some trying to find the best set up and wondered how this would change things. I currently have all the spacers below the clamp.
Cheers,
Kenneth
 

telephd

Guru
The primary benefit for me was in getting my hands lower. It made my S30 more comfortable and improved handling. I suspect that it also had some aero advantage as it got my hands out of the airstream to a degree.
 

Markopolo

Active Member
In an email with Robert about lengthening the chainstay which lowers the driver side boom/handlebars, he suggested that as the boom tends more toward horizontal the steering can get wonky. So, let us know what you find out.
 

hurri47

Well-Known Member
In an email with Robert about lengthening the chainstay which lowers the driver side boom/handlebars, he suggested that as the boom tends more toward horizontal the steering can get wonky. So, let us know what you find out.

That might explain why I prefer riding without the chainstay extension on my Silvio 1.0 despite having my hands higher than I'd prefer.

-Dan
 

Rampa

Guru
I think you would need your cranks so high that your pedaling axis was exactly perpendicular to your steering axis for it to be a problem. Simply not going to happen!

The closer you get to 90 degrees, the more leverage your legs have on steering. Most of us probably would not want our cranks at eye-level. ;)
 

Eric Winn

Zen MBB Master
I think you would need your cranks so high that your pedaling axis was exactly perpendicular to your steering axis for it to be a problem. Simply not going to happen!

The closer you get to 90 degrees, the more leverage your legs have on steering. Most of us probably would not want our cranks at eye-level. ;)

You mean like this? :D

10170334995_26770051ff_c.jpg


My cranks aren't really as high as it looks above but getting close. No problems steering. Here is another shot:

11067758946_01dca69bd6_c.jpg


-Eric
 

Rampa

Guru
Yep. Like that. Your not far off from that Eric! :)

If you draw a line from your hips that goes perpendicular through the head tube, you'll have it. I have no doubt you could ride it just fine.

I must confess that I have laid my Sofrider head-angle back to more-or-less 63 degrees (tiny shock), so it would be a more upward jutting line then for a 72 degree head-angle. I'm kind of the opinion that a very broad range of head-angles will work fine for MBB because of the inherent damping provided by our legs.
 

Kenneth

Well-Known Member
So i tried the boom lowered one spacer and then back up again. I wanted to like the lower configuration so that my hands would be lower but i really like it better up. I can't pinpoint a reason it just feels better.
 
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