# How will increasing fork rake affect handling?



## chrisclougherty (Mar 23, 2007)

I bought a used bike that is basically set up for crit racing. Very stiff, very quick. I like the bike overall, but would like to make the steering less twitchy. The current fork angle is 39 degrees. It has a 73.5 HTA and STA. How significantly would putting a fork with a 43 degree rake change the handling? How about a 45 degree? Thanks guys.


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## danl1 (Jul 23, 2005)

chrisclougherty said:


> I bought a used bike that is basically set up for crit racing. Very stiff, very quick. I like the bike overall, but would like to make the steering less twitchy. The current fork angle is 39 degrees. It has a 73.5 HTA and STA. How significantly would putting a fork with a 43 degree rake change the handling? How about a 45 degree? Thanks guys.


A noticeable amount, and probably not in the direction you intend. You might look first at your positioning on the bike - there's a chance you are set up a bit too far forward. Getting some weight off of your hands will make the bike feel more controllable, and will getting some weight off the front wheel will minimize the effect of flop that some consider as twitchy (it's useful but often forgotten to note that those are independent variables.)

That said, 'twitchy' is a surprisingly vague term, and the opposite sorts of adjustments might be what you are looking for. As an experiment, try raising and lowering your stem a bit - even though it might not be right for your fit in the big picture. A lower stem puts more weight on the hands, but doesn't meaningfully change the CG. Similarly, change the saddle setback, remembering that a further-aft saddle needs to be lowered to stay the same distance from the BB. Record your starting position, and make chnages one at a time to gauge their effect independently. You might not get somewhere better with this bike (in terms of fit) but you'll gain a better feel for the way a bike handles.

After you gain what you can from that exercise, you'll probably come to find that what you really want are longer chainstays. 

Bicycle Trail Calculator | yojimg.net


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## cxwrench (Nov 9, 2004)

chrisclougherty said:


> I bought a used bike that is basically set up for crit racing. Very stiff, very quick. I like the bike overall, but would like to make the steering less twitchy. The current fork *angle* is 39 degrees. It has a 73.5 HTA and STA. How significantly would putting a fork with a 43 *degree* rake change the handling? How about a 45 *degree*? Thanks guys.


you're using some incorrect teminology here which could confuse you and those trying to help you. when you say current fork *angle is 39°*, you must mean *rake*. and rake is measured in mm, not degrees, because it's not an angle, it's a distance. read this...it'll help. 
http://www.calfeedesign.com/tech-papers/geometry-of-bike-handling/


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## turbogrover (Jan 1, 2006)

More rake, (which is what you're really referring to) will give you quicker or more twitchy handling. Less rake will slow down the steering, but like danl1 said, I think you want to investigate how you fit on the bike, before considering a fork with a different rake.


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## chrisclougherty (Mar 23, 2007)

I'm sorry, you're right, I meant 39mm. fork rake. So, if the rake increases, to 43 or 45, I would think that would make the handling more relaxed. Is that right or wrong?


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## a_avery007 (Jul 1, 2008)

increasing fork rake reduces trail which makes the front end turn in easier..


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## m_s (Nov 20, 2007)

More rake/offset would make the bike steer into turns more quickly.


EDIT: beat by a hair.


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## bikerjulio (Jan 19, 2010)

chrisclougherty said:


> I'm sorry, you're right, I meant 39mm. fork rake. So, if the rake increases, to 43 or 45, I would think that would make the handling more relaxed. Is that right or wrong?


Wrong. The handling will become more twitchy and you will have less or no ability to ride "hands off".

I have a frame where with a 43mm fork it's impossible to ride hands off. With a 40mm fork it's OK.


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## Faapaa (May 19, 2008)

Ca. 57mm trail is a neutral steering, increasing tyre dim will help if you're running small tires and the steering feels twitchy


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## Scooper (Mar 4, 2007)

Perhaps a picture will help.

With a 73° HTA and 700c wheels with 23c tires, a 39mm fork rake will provide 63mm trail.

If you increase the fork rake to 45mm, the trail will be reduced to 56mm, which will be less stable than 63mm of trail provided by the fork with 39mm trail.


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## Kontact (Apr 1, 2011)

Rakes don't make a bike "stable" or "twitchey". The combination of rake and HTA produces trail that is either higher or lower than neutral. Rake alone is absolutely meaningless. Bikejulio's post doesn't make any sense because the rake has to work with HTA to make trail.

In this case, 73.5 degree HTA and 43mm of trail will make the handling neutral - as preferred by many famous builders. The current 39mm rake creates higher than neutral trail, which will feel more solid at higher speeds, but somewhat twitchy at low speeds. I don't see how that could be described as thing or another. Since you haven't said exactly how and when your bike feels unstable, no one can tell you if your handling problem can be improved with a different rake.

The primary things that impact handling are:
Trail.
BB drop.
Wheelbase.
Weight distribution.


Rake, HTA, chainstay length, stem length, etc are just things that can effect items on the above list. They aren't predictive of handling.

Is this a Klein?


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## bikerjulio (Jan 19, 2010)

Kontact said:


> Bikejulio's post doesn't make any sense because the rake has to work with HTA to make trail.


How did my post contradict this deep insight?

All I said was that on the same frame a 43mm fork was less stable than a 40mm fork (same Reynolds Ouzo Pro btw)


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## Kontact (Apr 1, 2011)

bikerjulio said:


> How did my post contradict this deep insight?
> 
> All I said was that on the same frame a 43mm fork was less stable than a 40mm fork (same Reynolds Ouzo Pro btw)


No you didn't. You said:


> *Wrong.* The handling will become more twitchy and you will have less or no ability to ride "hands off".


You said, categorically, that going to 43mm of rake is going to make it worse. Which isn't universally true, and if this is a low speed problem, completely backwards.

So I would say that both your posts are "Wrong." Generalizations of rake numbers and handling in general don't solve stability problems.


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## danl1 (Jul 23, 2005)

bikerjulio said:


> How did my post contradict this deep insight?
> 
> All I said was that on the same frame a 43mm fork was less stable than a 40mm fork (same Reynolds Ouzo Pro btw)


You are right; it doesn't. But at the same time, the change you experienced - while correctly noted - wouldn't be regarded by everyone riding that bike as 'less stable' or 'more twitchy.' They would if riding relatively slowly and hands off, but in high-speed cornering, they'd likely find it more sure-footed than the one of longer trail. At speed, a longer trail (all else equal) will tend to need to be 'forced' a little harder to start the turn, but will then seem to 'over-react' to the input. And some will call that behavior 'twitchy,' and I won't call them wrong. Just as I wouldn't call you wrong for calling it twitchy under the conditions that have meaning to you.

And just to highlight an earlier point: Bikes that 'can't' be ridden no-hands get somewhat more stable if the rider commits to it and gets their weight back. Proof: check the numbers on race bikes, and note how they seem to be ridden no-hands quite well by the pros. Sure, they are crazy good bike handlers, but pay attention to how they do it. They also happen to be going a bit faster than us mere mortals when they do it.


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## bikerjulio (Jan 19, 2010)

well I guess Scooper's wrong too


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## Kontact (Apr 1, 2011)

bikerjulio said:


> well I guess Scooper's wrong too


Tell you what, either Scooper made too much of a generalization, or Tom Kellogg doesn't understand bike geometry. Your choice:

Spectrum Cycles | Geometry


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## chrisclougherty (Mar 23, 2007)

*Is this a Klein?*

No, Kontact. It's a Seven on which I got a very good deal. I appreciate everyone's insights. 

I think I'm getting a better idea on this whole issue. Your comment on the 43mm fork is very helpful. The reason is that one of my other bikes is a Gunnar Roadie. I know from their spec page that these bikes have the same HTA as the Seven, but their forks are 43mm. The Gunnar handles really well in my opinion, while the Seven feels "twitchy" at lower speeds.

Would it be reasonable to assume that if I put a 43mm fork on the Seven that the handling would more closely replicate the Gunnar's?


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## JayTee (Feb 3, 2004)

Kontact said:


> No you didn't. You said:
> 
> You said, categorically, that going to 43mm of rake is going to make it worse. Which isn't universally true, and if this is a low speed problem, completely backwards.
> 
> So I would say that both your posts are "Wrong." Generalizations of rake numbers and handling in general don't solve stability problems.



Oooof. Yes, your pettiness can make you claim glorious rightness, but I don't think it is unreasonable to assume that the question anticipates apples-to-apples. The OP is talking about changing fork rake on an existing, purchased bike. If you want to assume that he's also going to chop up and rebuild the front end (i.e., change HTA) to feel superior to everyone else... bully for you, I guess.


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## Kontact (Apr 1, 2011)

JayTee said:


> Oooof. Yes, your pettiness can make you claim glorious rightness, but I don't think it is unreasonable to assume that the question anticipates apples-to-apples. The OP is talking about changing fork rake on an existing, purchased bike. If you want to assume that he's also going to chop up and rebuild the front end (i.e., change HTA) to feel superior to everyone else... bully for you, I guess.


Jaytee,

Did you read the OPs post directly before yours? He's saying that he is in fact having a low speed stability problem - the kind that comes from higher trail. This is exactly the opposite of most every post on this thread but mine, where I suggested that the problem was a bit more complicated than the High Trail = Stable mantra. My real sin here is disagreeing with the usual inaccurate generalizations without apologizing. So please append as many "IMOs" to my posts until you can stand reading a factual post about bicycle geometry.

I don't understand the rest of your post. I wasn't suggesting chopping up a bike - I was expanding on the stability issue, since it is not just about the front end. Fit issues are even easier and cheaper to address than fork rake. On that note:

Chris,

Seven's are usually pretty easy to ride, with decent BB drop. I would imagine it would be quite a bit like your Gunnar if you changed the fork. However, since weight distribution is a big deal, I'd first confirm that your actual saddle set back from the BB and reach from saddle to bar matches you Gunnar. Sitting to far forward or aft can make a bike seem unstable at low speeds, too.


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## Camilo (Jun 23, 2007)

chrisclougherty said:


> No, Kontact. It's a Seven on which I got a very good deal. I appreciate everyone's insights.
> 
> I think I'm getting a better idea on this whole issue. Your comment on the 43mm fork is very helpful. The reason is that one of my other bikes is a Gunnar Roadie. I know from their spec page that these bikes have the same HTA as the Seven, but their forks are 43mm. The Gunnar handles really well in my opinion, while the Seven feels "twitchy" at lower speeds....


I have absolutely no idea how these factors would affect what you're feeling and describing as "feels twitchy" vs. "handles really well", but, ....

How do the wheel bases compare?
How do the BB drops compare?

Again, I'm not an expert on this, but I'd think that over all, there's more to the "handles really well" vs. "twitchy", and I'd think weight distribution, center of gravity, etc. would impact objective and subjective feelings.

[just noticed someone had addressed this, but I'll leave this as-is anyway because I'm curious what people have to say about it]


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## C-40 (Feb 4, 2004)

*well...*



chrisclougherty said:


> I bought a used bike that is basically set up for crit racing. Very stiff, very quick. I like the bike overall, but would like to make the steering less twitchy. The current fork angle is 39 degrees. It has a 73.5 HTA and STA. How significantly would putting a fork with a 43 degree rake change the handling? How about a 45 degree? Thanks guys.


Some posters should spend more time reading this post and less time nitpicking the responses.

The posted 73.5 degree HTA and 39mm (not degrees) of rake would create a trail of 59mm, assuming a 336mm tires radius. That value would generally not be considered to cause twitchy steering, unless the frame is also a very small size with a short wheelbase and front-center. 

Some brands always use more trail on their smaller frames and less on the larger sizes, so the frame's wheelbase and front-center are also relevant.

The bike will become more stable at normal riding speeds with less rake (not more), to produce more trail. The opposite would be true at very low speeds, but not many folks except the climbers of really steep mountains, spend a lot of time at single digit speeds, where this might be an issue.

I've owned Colnago's in the 54-55cm range that typically have around 67mm of trail. I never had any problem with low speed stability during slow mountain climbs, but I did notice the sluggish steering on the high speed descent. I came to prefer a little less trail, like I found with my LOOK 585 frames, but not a trail as small as 56-57cm, which has come to be called "neutral" by some considered to be experts. I've owned a Cervelo R3 with that type of trail, combined with a very short wheelbase and didn't like it. I rode it on my regular 50 mile route, that included a 10 mile mountain climb, only four times before I tore the bike down and sold the frame.


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## Fivethumbs (Jul 26, 2005)

One man's "twitchy" is another man's "responsive".


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## artiefox1956 (Oct 14, 2021)

Kontact said:


> Rakes don't make a bike "stable" or "twitchey". The combination of rake and HTA produces trail that is either higher or lower than neutral. Rake alone is absolutely meaningless. Bikejulio's post doesn't make any sense because the rake has to work with HTA to make trail.
> 
> In this case, 73.5 degree HTA and 43mm of trail will make the handling neutral - as preferred by many famous builders. The current 39mm rake creates higher than neutral trail, which will feel more solid at higher speeds, but somewhat twitchy at low speeds. I don't see how that could be described as thing or another. Since you haven't said exactly how and when your bike feels unstable, no one can tell you if your handling problem can be improved with a different rake.
> 
> ...


will that nutweral hadlin


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## cxwrench (Nov 9, 2004)

artiefox1956 said:


> will that nutweral hadlin


What exactly are you saying (or asking since I can't tell) about the post from over 12 years ago?


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## pmf (Feb 23, 2004)

Yeah, after 12 years, we need to resolve this problem. 

Had I seen this 12 years ago, I'd say buy the fork with the rake your frame was designed for. Or in other words, the fork you are replacing.


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## velodog (Sep 26, 2007)

artiefox1956 said:


> will that nutweral hadlin


Sorry, I don't speak gibberish.


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