yz250roost said:
Hey guys,
I just wanted to warn all of you Renthal Twinwall users to check your bars as soon as possible. The Twinwalls seem to be cracking on the larger bar, right at the bend above the crossbar clamp, it will most likely on the side facing the rider. I have seen lots of these bars coming in over the last two months, and most of the cracks are very small hairline cracks that you wouldn't notice right away, you have to really examine the bar. If you find that your bar is cracking please send it to Renthal America as soon as possible for a replacement.
Jeff
Hey guys, Shawn Norfolk from Renthal here. I got wind of this thread, so I came right over.
Here's the skinny on the Twinwalls. The Twinwall came out in 1998. The bars that were produced PRIOR to 2002, had the problem of which you speak. Having said that, let me explain. It is a very simple problem and a very simple solution. Understand that even the bars that developed cracks were not deemed 'unsafe'. I know, I know...that sounds ridiculous, but allow me to explain further. The strenght of the Twinwall comes from the inner wall (a standard Renthal bar) that is surrounded (like a suit of armour) by the outter tube. The outter tube developed a crack because the balls that we used in the peening process were too large. As they put the compressive load on the outter surface, they thinned the material and the cracks would develop. Now, it didn't happen to all of the bars...just a few (probably 130-150 bars total out of the more than 100,000 that have been produced. Also, it only occurs in the area between the crossbrace clamp and the end of the outter tube. Why? This is where the material steps down from 1 1/8" to 1". That particular part of the handlebar is the thinnest part of the outter tube. NOT of the bar itself (as a whole) just of the otter wall. Now...You may ask yourself...How can a cracked bar be safe?
Here you go. On the Twinwall, the outter tube acts as an exoskeleton. It is made to take all of the abuse from the clamps, rocks, tie downs etc. All of these things abuse aluminum. The Twinwall is not going to have a fatigue failure (the number 1 cause of broken bars...with #2 being crashes). This simple fact makes it the safest bar in the world. The outter wall can be cut, cracked, notched etc...all the while the inner tube remains 100% perfect and as strong as it ever was. This is why no recall was done. The bar was not a safety issue. Had it been...we would have recalled them. We would NEVER put our customers at risk.
Now, How can you tell if your Twinwall was made prior to 2002?
simple. On the bars, between the clamps, there is a series of numbers. If it is not between the barmount/clamp area...it is out on the left grip end of the bar. The numbers look as follows:
918 59401801.
the FIFTH number (the 9 in this case) is the number that you need to look for. Your bar will either have a 9 or a 6. 6 was made before 2002, and 9 was made after 2002. Please understand again that just because you don't have a (9) bar...doesn't mean that your bar will crack. Again, only 1% of the bars developed cracks. However, if you crack your bar, send it to us and we will replace it.
The TwinWall is the strongest and the safest bar that is available. THAT is why all of our team riders use this bar. It is stronger, safer, less likely to bend, and more likely to make it through a crash. I hope that this makes it easier to understand for you guys/gals.