Straight Fork/ Head Tube Design Toe Overlaps/ What is Wrong?

blackstick · July 2014

Hello, how are you all

To start with I am a road cyclist with bit of background in art and design.
I also design bicycles/ just a hobby and I am also a bike fitter and mechanic/ self learned.

What I noticed from road bikes that have got straight forks is that they actually overlap and touches the toe part of one's shoe especially those of smaller size frames when the crank arm is on its leveled position.
PS - I do not mean all of them do so hence please do not get angry and shoot at me.

For example: BMC SLR01 (Size Small) Bought new from BMC dealer - fork hitting the toe by like a 1 1/2 inch whilst the crank arm is leveled - this guy cannot even turn whilst cycling and have to stop and straighten his bike every time before reaching a corner and position the crank straight all the time. And this is not because he set his pedal or cleat wrong/ or have a 200mm crank/ 172.5 - 2014 Ultegra to be exact. To not touch the fork as much he's set both the cleat on the very front which also greatly reduces his power transfer.
It was like a 2013 or older model - now BMC have got a bent on their new 2014 SLR model fork.
(Worked with one the same model but in Medium/ not a single touch!)

Then an EMC/ don't think its available in the UK (Size Medium) Bought new from dealer - not as serious as the BMC but fork is rubbing to shoe when crank arm is leveled.

Gir's/ forgot which model but a very high end frame from France supposedly also rubbing the shoes.
And lots and lots more as long as the forks are straight and especially if the frame is a smaller one.
I have a Bianchi C2C 2010 with a curved fork and I can throw the bike into corner with my crank arm position as leveled as I want when I go into a straight again and it never touch my shoe a bit which I brought in the UK whilst I was a student in Bristol.

Is the manufacturer just thinking, Oh hey make sure your crank is not leveled whilst turning eh?!
Or, This is the new trend, so suck and shut it up!
I am not trying to flame those whose got straight forks on your road bikes as I am sure not all of them do so but just worried with all this shoe rubbing forks may just kill someone and I have yet to read about anyone complaining about it.
So if you think I am wrong, I am

and sorry for writing.

Thanks for reading!

declan1 · July 2014

A friend of mine constantly falls of during slow cornering because of toe overlap. It's a serious issue in my opinion but as I don't really know about geometry I couldn't suggest how it might be fixed.

slowbike · July 2014

Change the head tube angle ....

styxd · July 2014

"Straight" forks or curved forks - it makes no difference to the rake/offset (typically between 40 and 50mm for road bikes)

So either increase the fork offset, or slacken the head angle if you want to avoid toe overlap. The handling may be compromised though.

blackstick · July 2014

Hi guys, so it seems that there are those who are aware of these

+1 for Head tube angle

My writing is not how to improve or avoid these toe overlap
Instead it is directed to the manufacturer! What is their logic in making a stylish fork or aggresive head tube angle in straight apart from it so called being more direct for steering response when the cyclist could fall to their death especially these are available on high end racing bikes that are made with the purpose to go quicker?! Again I do not mean all of them do so.

g00se · July 2014

blackstick wrote:

Hi guys, so it seems that there are those who are aware of these

My writing is not how to improve or avoid these toe overlap
Instead it is directed to the manufacturer! What is their logic in making a stylish fork in straight apart from it so called being more direct for steering response or bla bla bla when the cyclist could fall to their death especially when straight forks are available on high end racing bikes that are made with the purpose to go quicker?! Again I do not mean all of them do so.

Straight forks or curved, the rake/offset is still the same - with straight forks, there is a sharp 'bend' at the bottom headset bearing - but the relative position from the bottom headset bearing to the hub is the same.

The reason this is more common is people wanting more 'agile', responsive handling. This means greater headtube angle geometry and short wheelbases - this brings the wheel nearer the bottom bracket. The alternative, is longer wheelbase, slacker angles - which make a more predicable, steady ride - much like touring bike geometries.

But to be honest, you should rarely clash your toes and wheel. At normal speeds, you'll never turn the steering that far - and if you counter steer to that degree, you'll be freewheeling with the inside crank straight up as you'll end up tipping the bike right over into the turn. The only time I've ever clashed (and all my road bikes have overlap) is if I pull away on the turn - in which case I've learnt to position the cranks to compensate for that instant.

Bar Shaker · July 2014

If you draw a line through the headset, through the middle of the wheel and to the ground and then measure back to the centre of where the wheel touches the ground, this distance will determine the steering feel.

Reduce this distance by making the fork more vertical and the steering will be twitchy and nervous and less w2illing to self centre. Increase the distance by raking the fork further forward and the bike will not be willing to turn at all. If you go from a road bike to an XC or downhill MTB, you will feel this instantly. The MTB will not want to corner at speed.

The only solution would be to elongate the frame, but this will increase the rider reach and make riding over distances uncomfortable.

Just learn to always press down on the extended and stationary outside bend pedal, when you corner and you won't hit the wheel with your toes.

homers_double · July 2014

If I put my cranks at 3 o'clock whilst stationary and fannying about my shoes clash with the wheel, never in the time I've been riding has it happened. Like a poster says above, your outside leg would be at 6 o'clock if you're taking a corner that demands that sort of steering angle.

Speaking of o'clocks, its nearly beer o'clock

blackstick · July 2014

Really understand what you guys mean Goose, Homer and Bar Shaker.
Have been cycling for 10 years + and am sure you guys have the experience and inspiration too
I do the press down on my pedal whilst cornering, but WHAT IF this new cyclist does not know this?
ALSO > If an accident or unforeseen conditions that require a quick steer away whilst the crank arm is leveled?
I know I may have a chance to avoid it as my head tube and fork never gave me such a "touch" but this chance is lessened if I am on a bike which the toe and fork overlaps

Having the chance to fall over due to the overlap.. this is not logical as a cyclist and consumer
Also on some smaller sized bikes with such head tube and fork it is almost impossible to even turn depending on cleat position - so move the cleat as forward as possible to avoid it? What happens to cleat positioning for optimum power transfer? I know I position my cleat till the very end of my shoes which I prefer the feeling best/ meaning maximum toe fork overlap on certain bike

Like knowing your engine's having high compression piston that does not suit other running parts that is bound to explode whilst on high speed.. And there is not a motorcycle which body extends till covering the whole front wheel or a straight absorber not allowing much turning angle on our roads (well, not anymore)

homers_double · July 2014

At a guess, average joe isn't going to be riding a bike with such agressive geometry, more likely a tourer based or even a hybrid/mountain bike.

By the time this problem (and I do agree it's a problem) crops up I'd assume they're competant enough to corner properly. Take me for example, I've ridden MTB's for about 20 years and have recenlt got into road as well. I know the problem is there when I'm static but it's never been an issue whilst riding even at the slowest of speeds.

If you turn the bars at the angle you're talking about at a speed you're talking about into a corner you're talking about then I'd be more concerned with being flipped over the bars than anything else.

griffsters · July 2014

In real world riding of the bike I don't honestly see this as a major issue tbh. I have a small size bike and the toe overlap issue. On occasion at v.slow speed manoevering I get the tyre rub on my shoe but in normal bike riding not a problem.

For the odd occurrence, it doesnt merit the bike geometry changes required to design it out imho. A new cyclist will soon learn awareness of it just like gear changes, clipless pedals, cornering technique going uphill etc etc. All part of learning how to handle the bike.

neilo23 · July 2014

I have a large frame (or frames) and have toe overlap on all of them. This has not been a problem in over 25 years of cycling as the front wheel hardly needs to turn when cornering. Maybe more at very low speeds but it's not hard to avoid. Having said that I do sometimes wonder why it should hapoen at all when one thinks about the technology involved in designing modern bikes.

mercia_man · July 2014

The toe overlap controversy has gone on for years. Overlap is much more of an issue on small frames. I guess the modern fashion to emulate the pros by riding smaller frames with shorter distance between bottom bracket and front hub centres means more riders are now experiencing overlap. Bigger frames with longer top tubes don't normally have overlap. But designing a frame with full size wheels for a small woman, for example, involves big handling compromises if overlap is to be avoided.

I've only had overlap on one bike- an Orbea Orca in medium size with 55cm top tube. In normal use, overlap is not an issue. But you need to think what you are doing when turning sharply out of a T junction or when trying to do a U turn. It doesn't really bother me but I prefer not to have overlap.

I think it's a bit of a myth that you have to put up with overlap if you want a racy quick handling frame. My quickest handling frame was a medium size Principia RS6 Pro. That had plenty of clearance.

IanRCarter · July 2014

I have a 52cm Spesh Allez and get some toe overlap. It's only ever a problem when stopping at a junction and needing to make a sharp turn and at the same time forgetting about toe overlap. Broke a couple of Crud Roadracer mudguards this way, and it's made me stumble a couple of times when I haven't had mudguards fitted. It's never an issue when riding. The obvious solution is to give the bike a longer wheelbase so there is more clearance, but then you change the characteristics of the bike, as others have said.

keith57 · July 2014

It's quite normal, just get used to it. Only an issue at very low speed manoeuvring, worst effect is possibly scuffing your shiny shoes. At speed you never turn the bars enough for it to be any kind of problem. Can be a little surprising the 1st time I guess. A longish-wheelbase touring type bike might not be affected in the same way, but the handling would then be different to a race bike.

Straight Fork/ Head Tube Design Toe Overlaps/ What is Wrong?

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