Dbrk et. al. Head angle vs. reach

[Kane]

I am looking at buying a Turner Five Spot mtn bike. The head angle is 69 degrees. The top tube length of the medium is 23 inches and the tt length of the large is 23 and three-quarter inches.

My current ride is a medium Santa Cruz with an effective top tube length of 22 and a half inches.

Question: If the stem length is 110 mm on all the bikes, what is the actual reach difference for the bikes if the seat angles and position of the seat on the post are the same on all the bikes? (They are close.)

I am asking the question because the large feels pretty good. Most people ride the bike without too much handlebar drop. I should probably call Grant Peterson, because this is right up his alley.

Thanks in advance for any help that you might offer.


Cheers!

Kane

[Ray]

I am looking at buying a Turner Five Spot mtn bike. The head angle is 69 degrees. The top tube length of the medium is 23 inches and the tt length of the large is 23 and three-quarter inches.

My current ride is a medium Santa Cruz with an effective top tube length of 22 and a half inches.

Question: If the stem length is 110 mm on all the bikes, what is the actual reach difference for the bikes if the seat angles and position of the seat on the post are the same on all the bikes? (They are close.)


It would seem that head angle would make a relatively small difference in reach because there's so little head tube above the top tube. Several engineers were trotting out the geometry and trig to prove that there's EXTREMELY little difference with, say, 1-2 degree difference in head tube angle. Like a couple of mm or so. But E-Richie got into it and swore up and down that there was something like a cm difference for every degree of head angle or something. It degenerated into an amazingly confusing debate between math and the real world experience of one of our most esteemed frame builders.

Agreement was not reached. The longest non-answer you'll perhaps ever get,

-Ray

[Kane]

Grant Peterson had an article on his web site that discussed the effect of HANDLEBAR DROP, (difference between Saddle height vs. Handlebar height). His point was that, as the height of the Stem is increased there is a decrease in REACH (horizontal distance from the line of the seat tube to a vertical line from the center position of grip on the handlebars). Grant's bikes are often built with Quill stems and a steel fork, because he believes the material is superior overall to carbon.

The Turner Five Spot has a front and rear suspension travel of five inches. The seating position with its 73.5 degree (mildly steep) seat tube. In combination with the fact that due to the nature of the bike and the 69 degree head angle, most people ride the bike with a minimum of handlebar drop.

The net effect of this combination of factors, decreases the reach, changes the torso riding angle and shortens the reach. The top tube on the large frame is 23 & 3/4 inches. This feels like a 22 & 1/2 inch top tube length on a Santa Cruz Medium Superlight with a 71 degree head angle. I'm going to measure the reach on Saturday.

But a search for your clue on Roadbikereview.com produced no results. Further leads are appreciated. I am going to Lake Tahoe in a few weeks to ride a TURNER FIVE SPOT:

"Hi KANE,
We open tomorrow May 22nd. The Flume ride is mostly clear of snow now but it will be a few weeks for the Tahoe Rim Trail to open up. That is probably the best trail to get a good test on the 5 spot. What size bike do you need. We have a large now and are waiting for the medium to show up.
Thanks,

Max Jones
Flume Trail Bikes
High performance demo and rental mountain bikes
for Lake Tahoe's most beautiful trail.
Maverick ML7 - Turner 5 Spot - Specialized Epic
Max Jones <spoonerlake@pyramid.net>