You're taking about the bolts that clamp on the handlebars right? Well, I've never used a 2 bolt set before but all I can say is that the 4 bolt set probably clamps better based on what I think. Not too sure on this as well. You have pics of the 2 bolt stem?

 

I would say the only real difference would be the number of bolts you have to toque down. Seriously, it doesn't make a difference. Not too long ago, they made one bolt stems. The only thing I can see with a four bolt stem is they usually make the face plates smaller so maybe they are lighter.

 

I may be way off here but I believe the difference is 2 bolts.

In practice 4 lets you use smaller bolts since the torque on each is lower, and if one breaks your bars will probably still stay put. With a 2 bolt if one breaks you probably will too.

 

What's the difference? I always thought 4-bold stems were better because they were more stable.

Is that true? Briefly, what are the pros and cons of 2-bolt and 4-bolt stems?

I've seen too many handlebars completely detach when one of the bolts on a 2 bolt face plate has broken, to ever want to use one.

 

Probably depends on design of stem I would imagine....You might try and email Deda customer support and ask them. I asked them about bar position once and received a reply...from looking at a couple of photos of stems in a catalog, the 4 bolt stems have a wider clamp area, thus the need for 4 bolts....the difference in weight between a Deda Magic (two bolt) and a Newton (4 bolt) is 3g's. Also a heck of lot of difference in price ($64.99 vs $114.99)....

 

It's very easy to apply too much torque on the bar with 4 bolt stems.
"Ham-fisted" people should stick with 2 bolt stems. If you have a torque wrench, or are a careful person, a 4 bolt stem will work just fine.

 

Here's what Easton says....

What's the difference? I always thought 4-bold stems were better because they were more stable.

Is that true? Briefly, what are the pros and cons of 2-bolt and 4-bolt stems?

http://www.eastonbike.com/downloadable_files/tech_sheets/Distributed Stress Tech.pdf

 

It's all about marketing.

People want 4-bolt stems, so Easton is beginning to change its tune.

http://www.eastonbike.com/downloadable_files/press_releases/PR-bar-stem compatibility.pdf

 

People want 4-bolt stems, so Easton is beginning to change its tune.

http://www.eastonbike.com/downloadable_files/press_releases/PR-bar-stem compatibility.pdf

I tried this link and it's not working; any idea where it may be now? I've looked at Easton's site and can't come up with anything.

Help would be appreciated since I'm interested in the EC70 wing bar and don't want to have to buy another stem.


Woohoo, 1st Post!

kungfubiking blog

 

I would venture to say that properly designed two bolt stems are a ultimately safer design.They usually have more faceplate surface area grabbing the bars and less overtorqueing issues that create pressure points and high stress areas with the four bolt.I have had more HB slipping and resulting scratching of the HB with the four bolt than the two bolt stems I have used.Also many four bolt stems use smaller face bolts that are more prone to stripping/breakage.I would imagine that face bolts breaking on either system would/could cause a crash- but it has not happened to me yet.The four bolt stem does seem to have been born as a marketing ploy rather than on a sound engineering need for the design.Some of the fancy four bolt stems save a few grams by the use of carbon fiber faceplates-what happens when they break?

 

I tried this link and it's not working; any idea where it may be now?

Try this link again. You must have Acrobat Reader to see it. It came from the Easton website, Technical, Press Releases. But it only talks about the EC 90 31.8 bar, which was a "must use 2-bolt stem only" bar before this 2005 press release came out, so it doesn't answer your EC 70 Wing question.

http://www.eastonbike.com/downloada...com/downloadable_files_unprotected/press_releases/PR-bar-stem compatibility.pdf

 

I suspect the issue is with installation.

With a 4 bolt handlebar clamp stem, if you don't get the bolts tightened evenly side-to-side, you can create a point clamping force on one side of the handlebar. You'd rather have an even clamping force across the whole faceplate. This might be a good place to use an inch/pound torque wrench.

 

Interesting to see that Ritchey moved the bolts together on their new WCS stems. Sort of like a two bolt stem only there are four bolts.

 

Try this link again. You must have Acrobat Reader to see it. It came from the Easton website, Technical, Press Releases. But it only talks about the EC 90 31.8 bar, which was a "must use 2-bolt stem only" bar before this 2005 press release came out, so it doesn't answer your EC 70 Wing question.

http://www.eastonbike.com/downloada...com/downloadable_files_unprotected/press_releases/PR-bar-stem compatibility.pdf

Thanks, I later found it on another forum and got it to work. I can't imagine the two handlebars being that much different so I think I'll have the LBS install the EC70 using the torque wrench to assure it's not overly tightened.

 

I would imagine that face bolts breaking on either system would/could cause a crash- but it has not happened to me yet.The four bolt stem does seem to have been born as a marketing ploy rather than on a sound engineering need for the design.

I had imagined that breaking one bolt on a 4-bolt stem would *not* result in a crash since the remaining bolts would still supply enough pressure to keep the bar in place. It looks like a redundant system to me. With a single or double bolt the bars will always rotate freely if one breaks. That happened to me once, and I'd like it to not happen again...

 

I was thinking that if a four bolt bolt broke under stress, standing out of the saddle or sprinting,the handlebars would suddenly lurch down,possibly causing a crash.I have not seen any reports on the issue,so I am only guessing what would happen.What were the circumstances of your stem related incident.Has anyone had handlebar damage/breakage related to the four bolt stem system?

 

I was thinking that if a four bolt bolt broke under stress, standing out of the saddle or sprinting,the handlebars would suddenly lurch down,possibly causing a crash.

OK... I had to try it. I have a pretty light (130g 120mm) 4 bolt stem on my bike, and I just loosened one bolt completely, and I can still put all my 165lbs on the brake hoods and it doesn't budge. If one bolt broke on a 2-bolt faceplate, the bars would rotate freely.

A bolt will break from fatigue, so it won't necessarily happen when you would expect it to. Mine broke when I was on some bad pavement, but I wasn't really stressing it at the time... I had light pressure on the hoods. When the bolt broke the bars rotated forward and I went down pretty quick. It was an older single bolt steel stem... don't recall the brand.

 

Well that test makes me feel better about my four bolt stems that seem to be more problematic than the two bolt stems.Fortunately, stem bolt breakage appears to be a relatively rare occurrence.The handlebar slippage issue is what has bothered me more directly.

 

Is the issue more that a bolt will break or the extra forces will break the bars. I thought it was all about the bars but now I'm confused.

 

I like the 4 bolt because of more equal pressure across the handlebar. Less chance of stripping. Stronger. Better for a carbon bar.