2/17/14 12:07 PM

floor and TT measured as level.

granted there may be artifacts in the image due to lens aberrations (i.e., pin-cushing, etc) but the magnitude of those will be minimal. i was in the meat of the image (not near the edge of the lens) and would certainly be small fractions of a degree if anything.

to dan's point i'm just gonna STFU and ride this MFer...it's heavy and purty, will make for a great training bike this spring (if spring ever gets here) and i'll appreciate the lively handling of my other bikes even more.

2/17/14 1:44 PM

"i'll appreciate the lively handling of my other bikes even more."

I hear that, been riding the TCX with fenders and the Gary 29er with 47C Conti Comforts mostly.

The Scott is majorly lighter and more responsive..

2/20/14 6:29 PM

I can't understand this bike having such a steering problem as a result of subtle geometry features.

I suspect that the headset is binding, or the seals are tight, or the grease needs more time to give the ball track needed clearance.

I have a tremendous range of geometries represented by my own bikes, and none have such steering issues, at least not since resolving any headset bearing problems.

I am of course assuming that it doesn't pull to one side and that the facing (including the crown seat) was done properly, and that the headset is properly installed. It is common for a headset's adjustment to tighten up just by the final tightening of the stem's quill expander.

I also have a Merckx Century, same steering geometry as the racing model, and it rides no-handed as well as any other bike.

2/20/14 9:06 PM

the handlebars and wheel turn just fine, swings back and forth freely in the workstand, nothing is loose either, and no pulling to one side while riding.

overall the bike just handles slowly, requires more deliberate inputs (hands and body) to initiate a turn.

3/14/14 9:15 AM

picked up a digital angle-finder, with resolution down to 0.1degrees.

STA = 73 degrees (as i'd expect, just to validate the accuracy of this gizmo)
HTA = 75 degrees!!!

so i'm really befuddled by what might cause such ponderous handling as generally a steeper HTA reduces trail (<i>ceteris paribus</i>, of course).

http://yojimg.net/bike/web_tools/trailcalc.php

maybe what i'm experiencing isnt so much the turning of the handlebars as being slow (steering), but instead its the whole bike changing direction as being slow (turning). thinking out loud, maybe change-of-direction slowness is a by-product of the merckx's low BB vs. the front-end geometry (which looks fine, if slightly on the fast side).

Last edited by walter on 3/14/14 12:10 PM; edited 1 time in total

3/14/14 10:25 AM

The 75^ HTA does not surprise me. My Paramount is steep up front with a 5.0 rake. It turns fast and neutral when it is moving, but slower feels.. different.

I keep thinking of my Merckx EX when I think of your comments. There was something about the front end at speed with bumps i just did not like.

3/15/14 1:26 PM

I got around to measuring the HT angle of my 58cm Century model, and it's about 74.5 deg.

My angle finder is +/- .3 degr, but if one measures from both sides of the frame one can home in on a more-accurate measurement.

The century frame seat tube angle gets layed back to 72.6 degr or so.

This frame has quick, but linear, steering response, and I'm still looking forward to trying a longer (than 10cm) stem on this one, for better fit and perhaps calmer steering.

Which brand angle finder reads to +/- only .1degr?

3/15/14 8:04 PM

cen-tech, chinese made. i should clairify it has 0.1deg resolution, accuracy is 0.3deg.

3/16/14 8:16 AM

i.e., Harbor freight.

These things are good to have, but I use them mostly for fit considerations only.

I have no simple way to measure fork offset "rake", so I can only mildly predict handling characteristics from frame angles alone.

3/16/14 11:10 AM

I have no simple way to measure fork offset "rake"

Two pieces of sting and one plum-bob, and a tape measure. Rake and trail close enough for gov work?

3/16/14 12:06 PM

too sloppy/imprecise, even for gubment work.

much prefer straight-edges and right-angles! if not more accurate, at least i can delude myself that they are!

3/16/14 12:18 PM

Gravity does not allow for a lie. If you recall I asked earlier in the thread how certain you where the ground was level, how is it different on the 90^ plane? A good heavy metal bob with a point is always with in my grasp. I guess from using in construction for so many decades I like the tool/function myself. ;)

3/17/14 6:29 AM

What's the wheelbase on that baby? Responsiveness is not all about front end geometry.

3/17/14 7:44 AM

992mm w/ rear-wheel set where i ride it.

39.05" is a pretty short WB for a bike with a +58cm TT length!

fwiw...that's ~11mm shorter WB than my plastic colnagos w/ similar TT length.

3/17/14 9:49 AM

i get the bob hangs vertically, but how do you ensure the fork's steer-tube is consistently-reliably also vertical with any level of accuracy?

seems to me it'd be much EASIER, REPEATABLE and ACCURATE to instead get a long straight-edge (and spacers to allow clearing the fork crown) up against the steer-tube. clamp everything together and then you can measure the fork offset against the straight-edge (and adjust the measured result based on the thickness of your spacers). no bobs swinging around with a breeze or bump, completely repeatable, no eyeballing "yeah, that looks paralles/vertical" etc.

3/17/14 11:33 AM

That is a short WB for a bike our size to be sure.

As far as the Bob swinging, I guess if it is heavy enough... the one I have is quite pointy and solid metal. I never weighed it...

I see a surveyor's tripod with the bob under it sitting out even in the wind. the Bob settles if it gets moving.
They triangulate to confirm where what is on top of the Plumb Bob is of course. Yada

3/19/14 7:43 AM

the merckx has a legendarily low BB. havent measured mines, but lets assume it to be so.

my very smart buddy opined: <i>Ahh, low BB. That makes for a lower CG, which makes it require a larger lean input to get it turning.</i>

makes sense to me, as what i'm feeling is not so much steering but more changing direction as a function of a given weight shift.

3/19/14 10:46 AM

My Strong and the Bridgestone 400 both are as low as it gets pretty much 75-80. I never measured the BB on the EX, but neither the Strong nor the 400 have that trait which made me sell it off FWIW.

Maybe the combo of very un-steep STA and BB?
Because the Merckx frames I have scene seem to have
[in large size I ride] 71.# ^ STA and Low BBs.

3/19/14 2:18 PM

fairly deep, no?

found this thread from last year whilst building this merckx up, before i rode it: http://www.cyclingforum.com/phpBB2/viewtopic.php?p=137063

3/19/14 2:38 PM

Yeah, they are low BBs which was what attracted me to the EX to begin with. I like 75-80, at least I have myself convinced of this. For fast 1-2 rocket rides I like a lot less, like 67 maybe. But my body has forgot how to rocket, so that is moot. ;O