Understeer Whilst Cornering

Discuss light weight issues concerning road bikes & parts.
hlvd
Posts: 261
Joined: Sat Mar 05, 2016 4:54 pm

by hlvd

I can only compare this to a car understeering whilst cornering.

When I corner sometimes at speed my bike will want to run on and not follow the corner.

I’m not a pro so my bike skills aren’t amazing so I take full responsibility but is there a reason a bike would do that, do some turn in quicker, or is it just the rider?


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DaveS
Posts: 2553
Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

Anyone who has had motorcycle training learns that coutersteering is required to make a bike lean and turn. The first thing that I learned in my motorcycle training course was to push on the right side of the bars (which turns the wheel to the left). The bike will then lean right and turn right. The more you push, the greater the lean and the tighter the turn.

With a road bike that has hooked bars, is not quite as simple and the force required to turn the bars is very small, compared to a motorcycle. The principles are the same, however. The most common misconception is that countersteering only starts the turn and after that, the bike will continue to turn. That is not the case. It's real obvious with a motorcyle that requires a lot more force to turn, particularly at high speed. If you push on the right side of the bars to make a right turn and the turn is not tight enough, push harder to force the wheel to turn left. If you quit pushing, the bike will quit turning, immediately.

If you're descending a mountain at high speed with your hand in the hooks, it's more natural to push down on the right side to make a right turn, but what you're really doing is pushing the right side of the bars to the left, slightly and countersteering. Too many people think that turning a bicycle only involves weight distribution and not countersteering with the front wheel. They also tend to believe that a bike will keep turning once the turn is inititated by countersteering - not true of course.

I used to ride a 10 mile mountain descent with many curves about 100 times a year for 7 years. I never failed to make all of the high speed turns, but I did slide out once from hitting sand in a turn.

by Weenie


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Lewn777
Posts: 804
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by Lewn777

hlvd wrote:
Sun Sep 01, 2019 10:08 pm
I can only compare this to a car understeering whilst cornering.

When I corner sometimes at speed my bike will want to run on and not follow the corner.

I’m not a pro so my bike skills aren’t amazing so I take full responsibility but is there a reason a bike would do that, do some turn in quicker, or is it just the rider?


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What frameset do you have? I found that some framesets suit different styles differently. For me just in the last few years I have rented, 2 Specialized Tarmacs, a Trek Emonda, Cervelo R5, Scott Addict, Cannondale CAAD12 and own/owned a Specialized Roubaix, Fuji SL, Kuota KOM Air, and Giant TCR.

I would consider most of the bikes very good, but the TCR superb and the Cervelo not to my taste at all. I found that the Cervelo 'fell in' to the corners and needed to be 'stood up' at the end and seemed to front wheel scrub, a bit like understeering, whereas the TCR would just follow rider inputs exactly, I use body weighting to steer and counter-steering for me is just happening subconciously.

It does seem like choosing a size down if split between 2 sizes for frames helps, as does choosing a stem in the 110-120 range. So using a frame that's a bit on the big side and compensating with a short stem can be pretty ugly for handling.

Have a look at your tires and tire pressures, make sure they are normal for your weight and that you have tires you trust?

Find a downhill twisty ribbon of black bitumen near you and try different bikes if possible and see if you can find a preference. Most bikes seem very good, but with a few standouts and some duds.
Last edited by Lewn777 on Mon Sep 02, 2019 4:52 am, edited 1 time in total.

Mr.Gib
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by Mr.Gib

Don't blame yourself - it's the bike. The steering geometry (combination of head tube angle and fork offset) is primarily responsible for steering feel. Some bikes really hook up and carve with the slightest lean, other feel like you have to lean them more that you'd like to get them to hold their line in a corner. Some prefer the quicker turn in, others prefer slower turning response. Assuming there is nothing really funky about the geometry of your bike (what brand/model is it?) it is possible for you to adjust to it's particular characteristics and manage well in all situations - it just might not be to your preference. Sorry.

The interesting thing about the two different type of steering feel is that each has its advantages in various situations. You just have to decide where you prefer to have the various strengths and weaknesses. My Colnago carves beautifully with the slightest input. But it also has a far bit of flop in the steering when climbing, so you need to "manage" the front end a little more in climbing situations. My Parlee on the other hand sounds like your bike - it wants to run straight. I need to really work it in tight corners but at the same time it feels like I could climb out of the saddle with no hands - it just holds its line no matter how much I toss it around.

The Parlee is a short wheelbase, light, quick, agile bike, while the Colnago is longer and heavier and not as "racy". Don't assume these fundamental ride characteristics have anything to do with understeer or oversteer. A look at the head tube angles tells the true story. The Colnago has a slack head tube angle (72.5ish) and the Parlee is quite upright (73.5). The fork offsets are similar IIRC. Both bikes are the equivalent of a about a 57cm traditional geometry.

FYI if you want the front tire to bite and carve with less effort just shift your weight back when cornering. Sometime a few centimeters back is all it takes to get the front end to respond a little more. I am working from the assumption that whilst cornering your weight is divided between the outside pedal and the handlebars - not on the saddle.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

numberSix
Posts: 92
Joined: Sun Sep 23, 2012 1:53 pm

by numberSix

The issue is weight distribution. I doubt the frame geo is so slack it pushes.

This is yours?
viewtopic.php?f=10&t=156786

Being tall it’s very easy for you to move around on the bike. If you move too far back, the front tire is underweighted and pushes, too far forward and it’s overweighted and tucks.

I suggest getting scientific, and find a conscious reference point on the saddle while descending. You need to get off the saddle and put your weight into the pedals, put at least one thigh against the seat for reference, and test out torso placement such that the front tire is tracking confidently.

Sticky tires, proper pressure, and a smooth road will help this process.

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wheelsONfire
Posts: 2858
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by wheelsONfire

hlvd wrote:
Sun Sep 01, 2019 10:08 pm
I can only compare this to a car understeering whilst cornering.

When I corner sometimes at speed my bike will want to run on and not follow the corner.

I’m not a pro so my bike skills aren’t amazing so I take full responsibility but is there a reason a bike would do that, do some turn in quicker, or is it just the rider?


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Do you run very high pressure so the front wheel doesn't grip properly?
Do you have enough weight on the front wheel so it doesn't slip slightly?
Do you have a frameset a bit to long, so you need a short stem?
If you're not in the drop-zone, what happens if you are?

My bike steer good if i have it almost upright but lean in to the corner.
It corners faster (betterI if i lean my body more.

I had a longer frameset (longer reach - shorter stem) previously, now i have shorter reach and longer stem which distributes weight more forward then with the longer bike.
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

hlvd
Posts: 261
Joined: Sat Mar 05, 2016 4:54 pm

by hlvd

numberSix wrote:The issue is weight distribution. I doubt the frame geo is so slack it pushes.

This is yours?
viewtopic.php?f=10&t=156786

Being tall it’s very easy for you to move around on the bike. If you move too far back, the front tire is underweighted and pushes, too far forward and it’s overweighted and tucks.

I suggest getting scientific, and find a conscious reference point on the saddle while descending. You need to get off the saddle and put your weight into the pedals, put at least one thigh against the seat for reference, and test out torso placement such that the front tire is tracking confidently.

Sticky tires, proper pressure, and a smooth road will help this process.
Yes, that’s mine, you’re probably right about the weight distribution although I am running a 120mm stem.

A large frame is never going to handle as well, plus I’m a big guy and I weigh a lot.

I wish I could tell you all that I noticed this handling characteristic coming a windy Alpine pass, but the truth is that I was going round a traffic roundabout a bit too fast Image


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Hexsense
Posts: 897
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

Bike model and size?
There are so many bikes that, while medium and large sizes are designed properly, have very long trail value on smaller sizes (like s, xs and xxs). But there can be also opposite problem, extra tall bikes can be too unstable. But that's not the symptom you described.

Also, in response of bike going out of corner, many people try to force handlebar to turn the front wheel pointing into the corner. That make thing worse. You lose leaning angle doing that and the bike will further straighten up and out of corner. The correct response is to push the handlebar (and front wheel) a little bit more OUT of the corner to create more lean angle. Lean angle is the main thing that make your bike turn, not where your front wheel is pointing to.

hlvd
Posts: 261
Joined: Sat Mar 05, 2016 4:54 pm

by hlvd

Hexsense wrote:Bike model and size?
There are so many bikes that, while medium and large sizes are designed properly, have very long trail value on smaller sizes (like s, xs and xxs). But there can be also opposite problem, extra tall bikes can be too unstable. But that's not the symptom you described.

Also, in response of bike going out of corner, many people try to force handlebar to turn the front wheel pointing into the corner. That make thing worse. You lose leaning angle doing that and the bike will further straighten up and out of corner. The correct response is to push the handlebar (and front wheel) a little bit more OUT of the corner to create more lean angle. Lean angle is the main thing that make your bike turn, not where your front wheel is pointing to.
Trek Emonda 62cm.

That's interesting about turning the bars, I obviously wasn't leaning enough.


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Paperboy
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Joined: Tue Jun 04, 2019 5:38 pm

by Paperboy

In conclusion, everyone that rides a bicycle should also ride a motorcycle. This would then be common info :)

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wheelbuilder
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Joined: Wed Feb 08, 2017 2:10 am

by wheelbuilder

Just remember if taking a corner at speed turning right for example........push down with right hand and push down with left foot while left pedal is at 6:00. Simple to remember and works every time.
Never cheer before you know who is winning

TheRich
Posts: 383
Joined: Tue Jan 01, 2019 1:36 am

by TheRich

numberSix wrote:
Tue Sep 03, 2019 1:32 am
The issue is weight distribution. I doubt the frame geo is so slack it pushes.

This is yours?
viewtopic.php?f=10&t=156786

Being tall it’s very easy for you to move around on the bike. If you move too far back, the front tire is underweighted and pushes, too far forward and it’s overweighted and tucks.

I suggest getting scientific, and find a conscious reference point on the saddle while descending. You need to get off the saddle and put your weight into the pedals, put at least one thigh against the seat for reference, and test out torso placement such that the front tire is tracking confidently.

Sticky tires, proper pressure, and a smooth road will help this process.
In either one of those cases, the rider would probably end up falling....so that's not it.

Look through the corner, op. If someone is unsure in a corner and starts looking at the outside edge of the road for whatever reason, that's where they're going to go.

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Lewn777
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Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

I still think it's not really you I'm 6ft and happiest on a 54-55cm, but 52 and 56 are doable. You are likely very tall and also quite heavy, so at these larger sizes such as 60-62cm the geometry is somewhat guesswork, even with big brands like Trek. You could experiment and size down with a longer stem, but i can't guarantee it would work.

If you want to eliminate yourself as the cause I strongly recommend motorcycle track day tuition, or just read a book on it.

wingguy
Posts: 4283
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

Nah, it’s him. Sure some bikes turn in faster or slower, some have more or less stability, but fundamentally they can all corner without pushing wide.

Mid corner ‘understeer’ is going to come from lack of commitment to leaving the bike and looking where you’re going, not where you’re going to go. As said humans have a huge tendency in all sports to naturally go where their eyes are pointing. In cycling this is one of those nasty feedback loops that gets worse after it starts happening. The more you're worried about drifting wide, the more you look wide to check where you would end up, the more likely you are to drift wide and so on.

It takes a mental reset. Practise good technique and eyeline while going slower, then start adding speed again. Don’t expect to figure it out all in one go while going warp 10.

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euan
Posts: 1568
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by euan

Aye target fixation, you look at something and you end up heading towards it regardless.

by Weenie


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