?Straight bladed forks verses Curved bladed forks?

[janiejones]

Hi,

I'm using curved forks now, because I'm pretty short and have a rather small frame and top tube - I get a little better toe clearance with the curved than I did with the striaght on my previous bike.

toe clearance might be a thing you need to consider - between your toe and the front wheel when turning.

 

[alienator]

Hi,

I'm using curved forks now, because I'm pretty short and have a rather small frame and top tube - I get a little better toe clearance with the curved than I did with the striaght on my previous bike.

toe clearance might be a thing you need to consider - between your toe and the front wheel when turning.

Curved forks having nothing to do with toe clearance: that is a frame geometry issue. It CAN be addressed by getting a fork with a different offset, but whether that fork is curved or straight is irrelevant: the wheel will be located at the same place in space for a given offset, as long as the axle to crown distance is the same. However it's important to remember that if you attempt to change a toe clearance issue by changing fork offset, then you may have handling changes to deal with.

For anyone that doesn't understand why this is, do this: draw two points. Notice then that you can draw a straight line between those two points, as well as draw a curve between those two points. Whether you draw a curve or a straight line changes nothing about those points.

 

[pod]

Typical misuse of a word by technical people. I come from a building and construction background and 'rake' refers to an angle, slope, incline etc, but never a distance. Look in the dictionary and appart for various meanings related to an agricultural instrument, rake means "1. to incline from the vertical (as in mast, funnel, stem or keel of a vessel) 2. inclination or slope away from the perpendicular... 3. Machinery the angle between the cutting face of a tool and a plane perpendicular to the surface at the cutting point." Using the word rake to describe a distance is as stupid as measuring an angle in millimeters or inches but I'm sure some technical expert will have done it.

 

[mikesbytes]

Hi,

I'm using curved forks now, because I'm pretty short and have a rather small frame and top tube - I get a little better toe clearance with the curved than I did with the striaght on my previous bike.

toe clearance might be a thing you need to consider - between your toe and the front wheel when turning.

Toe clearance is a personal thing, doesn't worry me when my shoes rub the wheel. With the current fashion in shorter wheel bases, even large riders are going to have to get use to this.

 

[alienator]

Using the word rake to describe a distance is as stupid as measuring an angle in millimeters or inches but I'm sure some technical expert will have done it.

Actually, there are times when in optics we report an angle in terms of a unit of length; however, the reason that's done is that it's a reminder that certain approximations are being assumed, namely that the angles are very small. It's understood that the "length" is not an actual angle, but that the length divided by some normalized value (i.e., 1) is approximately the angle.

 

[supergrill]

Actually, there are times when in optics we report an angle in terms of a unit of length; however, the reason that's done is that it's a reminder that certain approximations are being assumed, namely that the angles are very small. It's understood that the "length" is not an actual angle, but that the length divided by some normalized value (i.e., 1) is approximately the angle.

Ah. Just one more reason why I'm going to standardize on expressing trail in femtoparsecs from now on!

 

[mikesbytes]

Ah. Just one more reason why I'm going to standardize on expressing trail in femtoparsecs from now on!

Time to get the ruler out. Now let me see 0.00029304423 femtoparsecs = 0.356 inches. Should also be measured at 25degC at sea level.

 

[9.8mps2]

Toe clearance is a personal thing, doesn't worry me when my shoes rub the wheel. With the current fashion in shorter wheel bases, even large riders are going to have to get use to this.

I'd want to defy fashion on that one ( which gets easier w/ age ! ) Many is the time in my short 2 years cycling I was thankful for the "rangy" 1040 mm wheelbase on my 61 cm . Things sure happen quicker than thay do on my VFR !
Glad this thread has rooted out some fellow m/c riders as well.
Not to hijack, but can any of you explain the phenomena of being able to eat a sandwich on the VFR at 100 mph, but being quite tense descending at a piddling 35 on the bike - just a lack of seat time ? The lack of leather ?
just being a puss ?

 

[531Aussie]

Hi.
I have the opportunity to buy some straight bladed Look full carbon forks to replace my existing curved bladed, alloy steerer forks.
It would lighten my bike up - a bit.
Are the straight bladed forks going to make the ride harsher?
Is the effective rake(if the rake noted is the same or similar) the same?

Cheers, Paul

In my opinion, from having owned about 20 different forks, rake has the least effect on handling compared to other parameters, such as blade size/shape/design, blade material, crown material and steerer material....and possibly even blade length.

A lot of a fork's compliance comes from the crown/steerer junction, so, generally, carbon steerers and crowns tend to be more flexy

In other words, a LOOK fork will feel different for many other reasons, regardless of rake. However, you probably wouldn't want to go from a big rake down to 40mm

 

[531Aussie]

Tire compliance be damned, there's a world of difference in riding (especially sprinting/out-of the saddle climbing/descending) a bike with a stout fork as opposed to a spaghetti fork.

I agree! I've transformed bikes by changing forks; I've stiffened up sloppy steel bikes, and I've made harsh alu bikes rideable with softer forks

 

[hd reynolds]

Hi.
I have the opportunity to buy some straight bladed Look full carbon forks to replace my existing curved bladed, alloy steerer forks.
It would lighten my bike up - a bit.
Are the straight bladed forks going to make the ride harsher?
Is the effective rake(if the rake noted is the same or similar) the same?

Cheers, Paul

Possibly if one is comparing a same steel (for example Reynolds 531 straight versus Reynolds 531 curved) or same aluminum type (inluding thickness etc) yes there is a slight difference in riding characteristics.

Nowadays manufacturers (both bike and tube manufacturers) manipulate tubing that thay can build certain ride characteristics to fork regardless of its design or shape.

 

[mikesbytes]

I'd want to defy fashion on that one ( which gets easier w/ age ! ) Many is the time in my short 2 years cycling I was thankful for the "rangy" 1040 mm wheelbase on my 61 cm . Things sure happen quicker than thay do on my VFR !
Glad this thread has rooted out some fellow m/c riders as well.
Not to hijack, but can any of you explain the phenomena of being able to eat a sandwich on the VFR at 100 mph, but being quite tense descending at a piddling 35 on the bike - just a lack of seat time ? The lack of leather ?
just being a puss ?

Motorcyles put out a lot more power than humans, the motorbikes are designed more towards handling using double cradle frames, front and rear suspension, large tyres where bicycles are designed for maximum efficency.

 

[dhk2]

I'd want to defy fashion on that one ( which gets easier w/ age ! ) Many is the time in my short 2 years cycling I was thankful for the "rangy" 1040 mm wheelbase on my 61 cm . Things sure happen quicker than thay do on my VFR !
Glad this thread has rooted out some fellow m/c riders as well.
Not to hijack, but can any of you explain the phenomena of being able to eat a sandwich on the VFR at 100 mph, but being quite tense descending at a piddling 35 on the bike - just a lack of seat time ? The lack of leather ?
just being a puss ?

Relative mass of the body and machine is the answer. On the moto, you're only a percentage of the total mass going down the road, ie, less than 50% typically. On a bicycle, many of us outweigh our rides by a factor of 10 or more.

 

[9.8mps2]

I'll buy both the above . When I go for a ride after a stint on the bicycle I usually look at the front wheel a couple of times thinking it is flat.
I used to just THINK I despised chipseal until I started pedaling. Tarsnakes and 1 1/2 " road cracks ?? Time to pay attention ! again regrets for the 'jack .

 

[Bigbananabike]

I wish I had ,my man .
More research reveals more contradictions. Reliable sources give both perceptions of rake as a dimension and an angle - and again, will sometimes contradict themselves in the same breath. They do the same regarding rake vs offset. http://en.wikipedia.org/wiki/Rake_and_trail#Steering_axis_angle - will mention the variance in rake as a term in the bicycling and motorcycling theaters. rats. Their illustrations of the relationships of parameters are helpful in gaining insight.
I reckon a lot of this confusion results from the lack of an engineering standard of terminology that SHOULD be able to encompass all aspects of the two wheeled world. eg: SAE, NACA, ASTM etc...
Of course if one governing body states "This is what it is", one discipline will state " We have always called it 'this', and will continue to do so".
This don't help the poor mechanic who ,when working on a global vechicle will encounter a mix of SAE and metric ( and , God forbid even Whitworth) fasteners. ( SAE is called "American" , or "regular" in much of the US.) Why we remain so ego/ethnocentric and will not join the rest of the planet is beyond me.
So to get (way) back to Paul BBB 's delimma - The real world stance of Mikesbytes vs. the fact that Paul wants the look ( pun intended) of these forks. Then the fork salesman will have his own slant on terminology complete with eye rolling and head shaking . Paul brings these trick goodies home , and his eval will predictably lack objectability as he's got his ego and need to justify his expense in the way. ( This is all hypothetical, Paul) A sort of double blind test with a bunch of forks , riders perceptions, and the time clock would yield some viable data. But then Paul would be a factory rider , complete with hotties competing for the privelege of applying his chamois cream for him, and he would be signing for a bazillion dollars to endorse a fork that he would attest as his secret for success - but the production version would bear only a passing resemblance to his personal setup.
Hey, the aftermarket folks gotta eat too.
Clear as mud ??
I think I picked a bad week to give up sniffing glue...

Mike S.

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If one of those hotties would apply my chamois creme while I'm still wearing my shorts...I'll endorse any fork

 

[Bigbananabike]

Hi,

I'm using curved forks now, because I'm pretty short and have a rather small frame and top tube - I get a little better toe clearance with the curved than I did with the striaght on my previous bike.

toe clearance might be a thing you need to consider - between your toe and the front wheel when turning.

============================================================
Thanks. I nor anybody else thought of that

 

[9.8mps2]

Except maybe the folks that market 650c wheels ?

 

[hd reynolds]

janiejones][/b]
Hi,

I'm using curved forks now, because I'm pretty short and have a rather small frame and top tube - I get a little better toe clearance with the curved than I did with the striaght on my previous bike.

toe clearance might be a thing you need to consider - between your toe and the front wheel when turning.

============================================================
Thanks. I nor anybody else thought of that

Not necessarily coz not all forks are the same - straight or curved.
For example the illustration below show no difference in rake between a curved (red) and a straight bladed fork (grey). They both meet the wheel hub at the same point.

If you need toe clearance you'll need a fork with a lot of rake (or slacker head tube angle) - curved or straight.

 

[mikesbytes]

Why don't you try before buying. If you are happy with them after say 2 weeks, then give him the money, otherwise give him the forks back.

 

[9.8mps2]

Not necessarily coz not all forks are the same - straight or curved.
For example the illustration below show no difference in rake between a curved (red) and a straight bladed fork (grey). They both meet the wheel hub at the same point.

If you need toe clearance you'll need a fork with a lot of rake (or slacker head tube angle) - curved or straight.

EXCELLENT ! This shot just clicked something for me. The difference between the steering head angle (rake) and the angle of the blades illustrate offset - as I defined it in first post. I incorrectly stated bikes were not set up this way - not so ! This example would in effect replicate the practice of leading axle forks on m/c's ( quick steering but goood stability ). The opposite on m/c's would be "kicked in" or negative offset by setting up a steeper fork angle than the steering head angle - yielding some semblance of handling to a chopper with a raked and extended front end. m/c's effect this differently by varying the setback of the forks in the upper and lower triple clamps.
Old dogs might not learn new tricks, but they can recall some they forgot...
thanks,
mps