toe overlap

[eddief]

I was riding with a friend today who did a bit of a no-speed crash on his bike when his toe clipped his front wheel. He rides a Merlin Solis and uses Look pedals. On my TST with spd's I'm nowhere near having my shoe hit the wheel. What are the significant variables that contribute to toe overlap. Is there something about Merlin geo in particular that would make this more pronounced than on other frames? I know Steve Rex considered this carefully when he built my frame, but I don't know what factors contribute to making overlap a non-issue.

[jerk]

this may seem obvivous but front center length is what causes toe clip overlap....many bikes have it particularly smaller bikes....it's not a big deal as long as you are travelling above 5mph. bikes turn by leaning. nonetheless when track standing on a bike with toe clip overlap it's important to keep your heels down. the jerk would never let toe clip overlap be a determining factor in frame geometry.

jerk

[eddief]

so is front center determined by ht angle and fork rake? and....?

[dbrk]

and...length of the top tube, hence one of the reasons we see it more commonly on smaller bikes. TCO is a non non on le velo francaise style and builders such as Herse, Singer, Routens, and others would go to nearly any lengths (yes, lengths) to avoid it. Personally I am in the ixnay and the TCOlay school too and want nothing to do fallin' over 'cause I'm a klutz. But given my penchant for frames that most guys think are Really Large (when, in fact, they merely follow the Daniel Rebour fit formula, pretty much...see Le Petit Vivre), TCO is a no show for me. One of the nice features of avoiding TCO in daysofyore was the dramatic swooping forward rake of oldschool bikes. Bend that fork LOW and deeeeep and forward abruptly at the last possible moment and your bike will take on exceptional good looks. When Curt Goodrich built my Serotta forks this past year I asked him to do just that; these are not as forward as a Frenchie but they are Very Cool. Anyway, TCO is another compromise to be avoided if possible and I am disappointed to hear that it appears on a "standard geometry" Merlin. Tsk. Tsk.

dbrk

[eddief]

I think I finally get it. After staring at bikes for three years and owning too many, I see that the angles can stay constant but by lengthening top tube and down tube you can move the rider further back to avoid tco. I think my friend needed, due to body proportions, a short top tube. I wonder if you can have a short top tube and still have geo that avoids tco?

[DWF]

What are the significant variables that contribute to toe overlap.

Toe clip overlap, while it can put you on the ground and a slow speed inconvenience, is not really a serious issue unless it's severe. Geometry variables that can effect TCO are:

top tube length
seattube angle
bottom bracket drop
headtube angle
fork offset
wheel/tire size*
crank length*
rider's shoe size*
position of the rider's foot relative to the pedal spindle*

The first five obviously affect front center dimensions and there its possible subsequent affect on TCO; those marked with an asterik are independant of front center.

To make TCO your primary focus on smaller frames means you're placing a greater emphasis on a minor slow speed inconvenience that you do on proper weight distribution and handling. The typical cures for TCO on small bikes is to use steep seat tube angles with longish top tube lengths (for small frames), short stems, and slack headtube angles with lots of fork offset. All can compromise the rider's fit & CG over the bike. For the truly small, the answer is to use 650C or 26" wheels and for the retro oriented, the 650B.

[Too Tall]

Funny you should mention all that DWF. about 6 months ago I built up the SWEETEST 650 Spectrum for a gal who used to be a top dog crit racer. She is very long legged and very short upper torso. I've worked on a couple of her other bikes it she never was comfortable and had serious toe overlap...not that there is anything wrong with that (blink blink). Tom NAILED it, the bike has her with wonderul weight distribution and a custom raked fork WOW! It is the second nicest custom I've ever laid hands on.

[Smiley]

check to make sure the cleats are on the ball of the foot. If positioned improperly then you maybe making toe overlap worse or yet better. I will also add that pointed shoes like Sidi or Shimano should be switched in favor of box toe shoes to again help minimize this issue. For small frames its pretty hard to avoid toe overlap unless you will accept a shorter stem work with a custom rake steel fork in combo with head tube angle adjustments etc. Sold many a frame with toe overlap . Never a performance problem unless track stands are desired. I have never sold a custom MTB frame with toe overlap cause its used in too many low speed maneuvers during single track riding.

[csb]