Written by Wally Wallace Monday, 27 June 2011 00:00
It has been obvious for some time now that the Crank Brothers engineers prefer to look out side of the box when designing new products. From the original Egg Beater pedals, introduced a decade ago, to their new Cobalt and Iodine component lines, Crank Brothers continues to push the envelope in design and function.
So with that we introduce the Cobalt 11 stem. We were very excited to get our hands on the new top of the line Cobalt 11 stem for several reasons. Number one it is a light weight XC stem made from "high-modulus, unidirectional carbon fiber." What bike geek wouldn't like fondle that for a bit. Secondly the stem features a design like not other stem we have seen to date. The first most glaring design feature is that there are no pinch bolts in the handlebar or steerer tube clamping area. Just elegant, smooth carbon loops.
The stem uses a genius wedge and plunger system to clamp both the stem and handlebar. The wedges are held in place, when the stem is not on the bike, by a long spring that runs inside the stem from one wedge to the other. (We have included a picture of the spring system in this article) The spring sytem, while being so simple, is extremely functional when installing the stem as the wedges do not fall or shift during installation. For installation the system makes use of, what is becoming a common trend in bicycle parts, a Torx bolt.
We have seen similar wedge / plunger systems recently on Thompson stems and further back, in the MTB world, on older Ringle and Syncors stems but Crank Brothers has taken this design idea to the next level. To date the other stems using a similar design only used the wedge for clamping the steerer tube which brings up the obvious question, if the wedge system was strong enough to hold your stem straight wouldn't it be strong enough to hold your bar as well. Well back in the day with 25.4mm handlebar clamps and thin walled aluminum / carbon tubing being the norm for mtb handlebars, most likely the wedge system would not have fared well in the handlebar clamp are.
The second, easily identifiable, difference was the use of a solid aluminum cylinder around the back of the clamping areas. Probably a result of the material being used and the traditional design style of the era. Carbon fiber has allowed bicycle and component makers to create intricate, elegant and functional designs that just could not be easily done with aluminum (the most common stem material in use for the past 15 years). The smooth carbon loops on the Cobalt 11 are designed to fit a 1-1/8" steerer tube and an oversize, 31.8mm, handlebar. With solid loops we questioned the stems ability to accommodate a bar with any substantial rise (feeding the bend through the loops would seem to be difficult) but a 50mm rise bar slides right through.
On the Bikeman scale our 100mm Cobalt 11 stem weighed in at 115grams, slightly under the advertised weight of 125grams. Very respectable indeed!
We are eagerly awaiting the arrival of the Crank Brothers Cobalt 3 stem with an ETA of early August. Original reports / reviews showed the Cobalt 3 with a wedge and plunger system much like the Cobalt 11 but recent supplier photos seem to indicate the use of a steerer tube and handle bar pinch bolt. Time will tell. Right now we do have a few Cobalt 11 Stems available in the 100mm length only. Here is teh link to the stem on our site: http://www.bikeman.com/SM8102.html
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