Calculate clamp force on bike handlebar

In summary: I think that you need to know what the contact area is between goose neck and handlebar. My lovely old road bike has a one-piece gooseneck with a single bolt. The fit between hole and handlebar is pretty snug without any tension on the nut (a lovely fit). With a little tenisoning of the nut, it holds perfect. 30+ years without a problem. Not so much the issue of one-nut, two-nuts, etc. but a question of fit, I think.Apologies I only posted that picture as a reference. Please see attached for a picture of the design and relevant dimensions. Both stem head and handle bars are made of stainless steel.
  • #1
FionnL
3
0
Hi Folks

I am looking for some help in a calculation if possible.

I am looking at a bike design where the handlebars are clamped in place in the stem using only 1 bolt - see the picture attached or link below for an example.

http://i.ebayimg.com/00/s/MTE5OFgxNjAw/z/rdgAAOxyrYFR2wbP/$(KGrHqF,!k8FHQwpchTzBR2wbP!Now~~60_35.JPG
Stem.JPG


There has been issues with the handle bars slipping forward when in use. I think that this is a manufacturing problem and not a design issue as this type of stem with one bolt is quite common.

However I would like to prove this mathematically. How do I calculate the force that the bolt and clamp have on the handlebars? I would like to compare a calculation of 1 bolt versus 2 and 4.

Any help greatly appreciated.

Thanks
 
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  • #2
FionnL said:
Hi Folks

I am looking for some help in a calculation if possible.

I am looking at a bike design where the handlebars are clamped in place in the stem using only 1 bolt - see the picture attached or link below for an example.

http://i.ebayimg.com/00/s/MTE5OFgxNjAw/z/rdgAAOxyrYFR2wbP/$(KGrHqF,!k8FHQwpchTzBR2wbP!Now~~60_35.JPGView attachment 78082

There has been issues with the handle bars slipping forward when in use. I think that this is a manufacturing problem and not a design issue as this type of stem with one bolt is quite common.

However I would like to prove this mathematically. How do I calculate the force that the bolt and clamp have on the handlebars? I would like to compare a calculation of 1 bolt versus 2 and 4.

Any help greatly appreciated.

Thanks

I think the problem with this type of goose-neck comes about when the curvature of the sleeve does not match the curvature of the cylinder for the handlebars. If the diameter of the handlebar is undersize, you will be making contact with a very small area on the top and the bottom. As you crank down on the nut, you may be using a lot of force to deform the gooseneck, without making better contact. If the diameter of the handlebar is too large, you will be biting at the edges. I think both cases will allow the handlebar to slip. I have had similar problems with other types of hinged pieces.

With the handlebar in place, look for gaps. You might try putting some kind of material in between to get a better grip.
 
  • #3
Quantum Defect said:
I think the problem with this type of goose-neck comes about when the curvature of the sleeve does not match the curvature of the cylinder for the handlebars. If the diameter of the handlebar is undersize, you will be making contact with a very small area on the top and the bottom. As you crank down on the nut, you may be using a lot of force to deform the gooseneck, without making better contact. If the diameter of the handlebar is too large, you will be biting at the edges. I think both cases will allow the handlebar to slip. I have had similar problems with other types of hinged pieces.

With the handlebar in place, look for gaps. You might try putting some kind of material in between to get a better grip.

Cheers for the reply. Yes this is what I think is happening but I am being told it is the design... so I want to prove with maths that it works so I am looking to calculate the clamping force of 1 bolt versus 2 or 4.
 
  • #4
FionnL said:
Cheers for the reply. Yes this is what I think is happening but I am being told it is the design... so I want to prove with maths that it works so I am looking to calculate the clamping force of 1 bolt versus 2 or 4.

I think that you need to know what the contact area is between goose neck and handlebar. My lovely old road bike has a one-piece gooseneck with a single bolt. The fit between hole and handlebar is pretty snug without any tension on the nut (a lovely fit). With a little tenisoning of the nut, it holds perfect. 30+ years without a problem.

Not so much the issue of one-nut, two-nuts, etc. but a question of fit, I think.
 
  • #5
Apologies I only posted that picture as a reference. Please see attached for a picture of the design and relevant dimensions. Both stem head and handle bars are made of stainless steel. I agree that what you are describing is most likely the problem but I need to prove the design first and am looking to find the right equations.
Handlebar_Clamp.jpg
 

1. How do I calculate the clamp force on my bike handlebar?

The clamp force on a bike handlebar can be calculated by using the formula F=μN, where F is the clamp force, μ is the coefficient of friction, and N is the normal force. The coefficient of friction can be determined by the type of handlebar material and the type of clamp material. The normal force can be calculated by multiplying the weight of the bike and rider by the sine of the angle between the handlebar and the stem.

2. Why is it important to calculate the clamp force on a bike handlebar?

Calculating the clamp force on a bike handlebar is important because it ensures that the handlebar is securely attached to the bike's stem. If the clamp force is too low, the handlebar may slip or become loose while riding, which can be dangerous. If the clamp force is too high, it can damage the handlebar or stem.

3. How do I determine the coefficient of friction for my bike handlebar and clamp materials?

The coefficient of friction for bike handlebar and clamp materials can typically be found in manufacturer specifications or online resources. It may also be helpful to consult with a bike mechanic or engineer for assistance in determining the appropriate coefficient of friction.

4. Can I adjust the clamp force on my bike handlebar?

Yes, the clamp force on a bike handlebar can be adjusted by loosening or tightening the bolts on the stem. However, it is important to ensure that the clamp force remains within the recommended range to prevent damage or accidents.

5. Are there any safety precautions I should take when adjusting the clamp force on my bike handlebar?

Yes, it is important to always follow the manufacturer's instructions and recommendations when adjusting the clamp force on a bike handlebar. It is also important to regularly check the clamp force and make adjustments as needed to ensure the handlebar remains securely attached to the stem.

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