Toe overlap?

[cycleman_21]

OK,
I just read something about this in the Image gallery and need to know what this implies to.Should there be some?If so,how much?I bought a Fierte and there is definately some on it, if it's what I think it is.Hoping I'm ok :confused: thanks for any help

RC

[jerk]

do you make alot of very slow speed u-turns in your driveway? do you find a strange need to track stand without your heels pointed down? didn't think so.
don;t worry about it. just don't tell the cpsc.
jerk

[dbrk]

Okay, I made the unflattering comment about what I take to be too much TCO on the bike in gallery. The reason I say that is that it _is_ possible to avoid this _extent_ of TCO even on short top tube bikes and I am confounded to see it so commonly dismissed as irrelevant.

Serottas, by and large (an expression, btw, that is actually an impossibility since it refers to sailing a square-rig on the bowline and "large", i.e., wind abaft the beam, which are two different, incommensurate things...), are "race" bikes, recreational fastboys, we might all call them. Some are designed for more "comfort" fits but almost always within the parameters of a racer's design and very much in that tradition, which Americans seem to have learned during the bike boom years. We see almost none of the concerns of long-distance audax and randonneur style riders in American designs. In these traditions, largely French and English, TCO is unacceptable and is designed out of the bikes. Why and how?

At very slow speeds, not just parking lot speeds, but at wobbling speeds that occur when you are out for long, long rides, a knock on the fender (yes, fender, something almost no American builder builds into the design...) can topple you. But to defeat TCO with relatively short top tubes you have to increase rake and thereby reduce trail. This would apparently cause "handling problems" at higher speeds. However, audax riders generally do not average more than 18mph so high speed stability is less of a concern than low speed. Still, there is another solution involving an issue that is also not current among American builders who are wedded to limited clearance carbon forks. By using a considerably larger tire the audax bike increases pneumatic trail, that is, it compensates for trail by increasing the tire's footprint. Since most modern race bikes, including all the Serottas that use carbon forks, assume very skinny tires, usually not more than 25c because of clearances (IF you can fit even some 25s!), such bikes offer no option for increasing trail with the tire. Audax bikes should start at about 27c (a true 27c looks like what most companies call 28c...) and often go up to 38c (look at Vittoria Randonneur tires). The result is that a decreased geometric trail is compensated pneumatically, as it were, and this stabilizes the bike's handling.

Now on Serottas that are "designed to go fast" and are compelled to use skinny tires (by fork's leading the design agenda), TCO will be less problematic because average speeds are putatively higher, stability at speed is the priority, and "parking lot speeds" are rare. So, the jerk is right. However, on a true audax bike TCO can be designed out of the bike. I have often disagreed with my dear pal Grant Petersen who will tolerate a certain amount of TCO for the good reasons the jerk and others note. These are _smart_ bike designers, so I understand entirely the low risk of _most_ TCO. But when there is pronounced TCO or you are in fact a slow speed, long distance rider, then it should be a high priority to eliminate it. I ride larger frames and it's almost never an issue on my bikes. But with the Singers and Herse bikes, with short top tubes (57.5tt on 61cm frames), TCO has been designed out of the frame. How? The bike is made for 28c tires and can handle some 32s. (Fat tires are NOT slower, for you physics fans...) If you use smaller tires on such bikes they handle differently, too quickly at slow speeds (betraying the lower trail number). Jan Heine has discussed this matter in the VBQ. It's not an unfamiliar issue, however, when you look at the history of frame design in light of different traditions of riding.

Sorry for the prolixity. I hope my comments have been taken in a constructive light. My goal is not to discredit nor to sound "angry" about anything, just to point out that cycling has a rich history of design and within those traditions there are multiple solutions to problems, such as TCO.

dbrk

[jerk]

dbrk is right....toe clip overlap is fine on a racing bike....but not on an audax bike, a touring bike, or any sort of bike you'd like to ride casually, or for hours upon hours on end or with fenders.....sorry, dbrk you are right the jerk is wrong. sometimes he forgets most bikes aren't used in the manner that the jerk uses his bikes. his humble apologies.
jerk

[gt6267a]

a short story about tco that i've told before, maybe here? i bought a used serotta and rode it some miles, let's say 1000. didn't know there was any tco. then, i was out riding with a friend who had about 5 miles in his legs for the season but insisted on going hill climbing. we were going 3 mph up hill and it was difficult to keep my balance. i was jerking the bars back and forth, my foot hit the front wheel and i thought to myself, "what the f was that?" it didn't make me crash or anything, but it was a wake up call to ride a little quicker.

as i understand tco, it's a more pronounced problem in smaller sizes. riding a 53, there is tco on every bike i ride, but it's never been a problem.

[Dr. Doofus]

downward dog daddy is the man...

as long as foodrey is on this "stealth waterford" thing with the Gunnar, a Heron might as well be in the bike room...pimp it with some fenders, downtube shifters, brooks....

[Kane]

I was in L.A. a few years ago doing my best to have fun. I went out to the west L.A. area to visit some bikes stores. I found a 'Yagamuchi' (sp?) steel frame that looked like a good fit. After measuring the frame, handing over the license, mounting pedals, adjusting the saddle height, and putting air in the tires, I was ready for my test ride.

I took the bike out into the neighborhood and decided to turn around at the second driveway to get the handlebar angle adjusted. As I made my very tight (warning!), very slow (double warning!!) turn, my foot hit the tire and I almost fell over. My own ride bike had minimal TCO and this one had a lot, a whole lot. Luckily I was using my own pedals and shoes so my release was fast and sure. I'm pretty sure that they didn't want a ding on their beautiful bike.

I might have bought that bike if not for an allignment issue with the fork. The TCO would not have bothered me on this type of frame. Other than the issue of not knowing it existed prior to my test ride.

Cheers,

Kane

[vaxn8r]

I have a bunch of TCO on my OCLV...with fenders on it. It's really not a problem but if I were newer to the sport, working on bike skills it could have been a problem....at times not unlike one's first experience with clipless pedals. Heh heh. Oh yeah, I still recall back in '85, the intersection in Covington, Kentucky where I spilled going 0.2 mph my first ride with those new Looks. I think everyone went down at least once with clipless.

[erty65]

(Fat tires are NOT slower, for you physics fans...)

Is that just a theory? :confused:

[cycleman_21]

Thanks for the replies,it all makes more sense now,just what I figured it was but I sure feel more at ease with it.My old bike had almost none,my new one is a little more noticable.Sounds like it'll be fine,I wanted a little faster position in my riding style.

RC

[Kevan]

something to be aware about, rather than concerned about.

Keeping in mind the comments above.

[Eric E]

For me, at 5'7" with a set back position due to heavy shoulders and short legs, a little toe overlap allows me to use standard 700c tires and a 11cm stem. When redesigning my Serotta rapid tour (72 degree seat tube, 71.5 degree head tube), I suggested consideration of lengthening the top tube (which would require a shorter stem), but Kelly said that the longer front-center would not be optimal. So, for me, it seemed like the minimla toe over lap was optimal.

For my wife, at 5'4", toe overlap was necessary to bring the handlebars her Rapid Tour (73 degree steat tube, 71.5 degree head tube) closer to her - as it is, she has a 6 cm stem (or stub, as she calls it), whose quickness is counterbalanced by more trail on the bike. Yes, we could have gone with 26 inch or 650c tires on her bike, but that would mean carrying twice tires/tubs while touring and not being able to find good replacements nearly as easily. We had a friend blow out a 650c tire on a ride in northern Colorado, and we only found one replacement in Greeley, a moderate sized city - it was the personal property of a local shop tech...

No crashes so far and we love the bikes...

Eric

[alembical]

I have one bike with TCO and unfortunately it is my fixed gear with fenders. It would not be as bad of a problem on any of the other bikes, but on a fixed gear, it can get interesting. It has lead to many close accidents, but I have become more aware of it as time has gone on, and haven't had a close call lately. Knock on wood.

Alembical

[cookieguy]

I ride a 53cmx53cm Legend with ~2cm of Toe Overlap.... One of the more frightening rides I have ever been on was the first couple miles of last years Moonlight Classic in Denver....1000s of people going very slowly and not maintaining any sort of line. I had more than a few low speed tire-toe interactions... This year I will ride my MTB!