Stem: 4-bolt bar clamp or 2 bolt -- why the difference?
01-30-07, 10:13 AM
#1
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Stem: 4-bolt bar clamp or 2 bolt -- why the difference?
I see stems with 4-bolt fronts or 2-bolts. I've searched but cannot find what the difference is between them.
Higher end/more costly stems seem to have 4 bolts while lower end have 2 bolts.
I think on one carbon bar I read it must use a 2-bolt stem, I assume so you have more even pressure coming from the middle of the clamp as opposed the the ends/corners so as not to chip the bling.
But is there a reason to choose one over the other?
Higher end/more costly stems seem to have 4 bolts while lower end have 2 bolts.
I think on one carbon bar I read it must use a 2-bolt stem, I assume so you have more even pressure coming from the middle of the clamp as opposed the the ends/corners so as not to chip the bling.
But is there a reason to choose one over the other?
01-30-07, 10:15 AM
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The wider 4 bolt design just spreads out the clamping pressure on the face of the bar.
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01-30-07, 10:27 AM
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01-30-07, 10:37 AM
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What the Easton system does not tell is that it makes the bars flex allot more. Go with a traditional 2 or 4 bolt design from a reputable manufacturer and avoid the uber light stems and you will get years of reliable, trouble free, and stiff riding. For a carbon bar, many stems explicitly state that they were designed to be used on carbon bars - focus on those. I would personally recommend a Thomson.
01-30-07, 11:08 AM
#5
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Thanks for the replies. So while the 4 bolt design puts the most stress on a handlebar, it probably also means the bar will flex the least.
01-30-07, 11:11 AM
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Yes, the bars will flex the least.
As for stress, in general, yes, but in reality, it would more than likely be a case by case basis for each stem, and would change with different bars.
As for stress, in general, yes, but in reality, it would more than likely be a case by case basis for each stem, and would change with different bars.
01-30-07, 11:49 AM
#7
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Originally Posted by yeamac
Thanks for the replies. So while the 4 bolt design puts the most stress on a handlebar, it probably also means the bar will flex the least.
BTW, I tested my 4-bolt stem to see if this was true... and I've experienced what happens when a 1-bolt breaks...
01-30-07, 12:07 PM
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I think that Easton test is incorrect. The clamping on the front and not the top is a disadvantage to peak stresses. They don't show stresses around the bar as they will change as you go around the bar radially. I'd go with a traditional 2 or 4 bolt pattern. I tried my 2 bolt Thompson with 1 bolt and it felt secure in some but not all configurations (depends which bolt fails) but I've seen a lot of 2 bolt designs I wouldn't want to try that with. It doesn't take much loosening for a bar to rotate and dump you (I've had a couple bar rotations although I managed to hang on).
