Boom Adjustments

When my VK2 is good...it is very, very good. When it's bad, I'm not a happy camper. This is one of the smoothest riding, comfortable and fastest bents I've had. But I have had a devil of a time getting it dialed in correctly. After I replace the broken boom...see below...and installed a FSA crank things were going very well. I changed to a Rotor Crank within the last month or so and have concluded that I need to bring the boom in a hair to give me the correct pedal stroke position. I was extending too much and feeling some strain in my legs.

I put the bike in a trainer and removed the screws that secure the boom in the boom socket. After putting some protective tape on the nose of the boom, with a rubber mallet, I tapped the boom smartly in an attempt to shorten it about 1/4". I arrived at the 1/4" figure by doing some measurements, with the help of my local bike mechanic, who is expert at fitting bikes. He concluded that 1/4" shorter boom would be about right. I tapped and tapped and the boom wouldn't budge. So, I tapped the other way on the crank arm spindles and was easily able to remove the boom.

I took a flashlight and peered inside the boom socket. Ahhh sooo, there was a large piece of boom material (resin?) adhering to the side of the socket just at the point were the end of my boom used to be. It was that piece of resin that was preventing me from tapping the boom further into the socket. Now this was a big obstruction. Filing it out of existence or knocking it off didn't seem feasible.

So, I decided to hack saw off about 1/4" of the boom. I dared not take any more of the boom off because I am approaching the point where the end of the boom is getting too close to the inside most clamp screw. When I did the original fitting, I sawed off 2". I figure I need to be past the clamp at least 70 mm to keep the boom securely enscounced inside the socket. I was able to take the quarter inch off the boom and easily tap it inside the socket. After tightening the clamp I discovered that my pedaling now felt perfect. I haven't gone for a long ride yet, but my short test ride indicates that I am now dialed in to the sweet spot.

A friend, actually one of my fellow BROLers, said to me that the VK2 is like a fine sports car. You have to have fun fiddling with it to get it just right, and then fiddle again. Well, I have done more than my share of fiddling, and it hasn't exactly been fun. But, I do love riding this bad boy and I guess that 's what counts. Whew!!!!! I just finished what felt like delicate brain surgery.