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2 Bolt and 4 Bolt Threadless Road Stems(9 posts)

2 Bolt and 4 Bolt Threadless Road Stemsbobobo
Jan 31, 2003 11:19 PM
Are there any advantages or relative disadvantages of 2 bolt versus 4 bolt threadless road stems?
2 more bolts...C-40
Feb 1, 2003 5:41 AM
The four bolt models have 2 more of the same size bolts. There will be far less stress on the bolts. The 4-bolt models will keep the bars from slipping with far less torque on the bolts.
Stems are a component that I've grown wary of.Spoke Wrench
Feb 1, 2003 6:26 AM
I've never botched a stem job myself, but I've heard of enough stripped high end stems that I've grown very cautious.

It looks to me that with a lot of high end stems, there is a pretty narrow range between the handlebar slipping and the bolts stripping out. That would appear to support C-40's contention that four bolts are better.

I can see a couple of other issues, however, that might color that opinion:
The first is "How do you know when you have enough torque." Most guys just tighten the bolts based on their past experience. If you are going to use the same high torque anyway, you can strip out a four bolt stem just as easily as a two bolt stem.
The second has to do with installation technique. You would like the full surface area of the stem to bear evenly on the handlebar. This means that you should have all four bolts evenly torqued and that you should gradually "walk down" the torque on the four bolts. If one side of the stem face is significantly thghter than the other, you may have only a narrow ridge actually holding the handlebar which may cause the handlebar to slip.

The bottom line is, if I were paying $80 ot $100 for a stem, I'd find somebody who has an itty bitty torque wrench to install it.
Stems are a component that I've grown wary of.daniel_2001
Feb 1, 2003 8:20 AM
I have a two bolt Ritchey stem. I have had concerns about the possibilty of failure. I emailed Ritchey. I was told that there are no reported cases of a failure in the two bolt stem. I guess I too would feel more comfortable with four bolts. I think that the real reason they went to four bolts was to decrease the weight. They made it out of lighter material, and thus needed more points of contact.

Daniel
??Fez
Feb 1, 2003 10:56 AM
4 bolt to decrease the weight? You say 4 bolt stems were made of a lighter material and thus need more points of contact to stay secure.

However, bolts weigh something, and the contact area is larger, so it looks like a net weight loss of zero.

The only other thing they could do is hollow the center area of the faceplate, as seen on Deda and Ritchey Wcs. Thomson's stem is not hollowed out on the faceplate, but it also is no lightweight.

I think either design is fine. For most, make sure headset is adjusted properly, bars are in good shape, and stem bolts are torqued properly.
1 boltAndy M-S
Feb 1, 2003 5:10 PM
I have used 2-bolt (threaded) stems in the past, but not long ago I decided that I liked my face and teeth, and went back to single-bolt stems. If the bolt fails, the stem is still snugged tight enough to allow you some control.

Just my $.02.
4 bolts good. 2 bolts ba-a-a-a-a-ad. ;-) nmSpunout
Feb 2, 2003 8:53 AM
wrong. 2 bolts good; 4 bolts baaaaaad.legs
Feb 3, 2003 6:55 AM
there was an article on the easton site that explained the science behind this thought. something about better and more even distribution of pinch force between two bolts...(even though it defies logic at first glance).
That article doesn't say ...the other Tim
Feb 3, 2003 12:37 PM
that two-bolt stems are better than four-bolt stems. It simply points out that it is easier to over-tighten a four-bolt clamp, and that the stress is at the edge of the clamp. If you're worried about breaking or stripping the bolts, four is obviously better, as C-40 pointed out. If you're worried about overtightening the clamp, don't do it, as the Easton article warns.

Easton's flagship road stem, EM90, has a four-bolt clamp.

I like two-bolt clamps because they're easier to install.