I recently drilled the swingarm on my DHR to lower the BB and slacken the headtube angle. I have read a lot of discussion about this procedure online, and noticed a number of conflicting opinions about what was necessary to make this mod properly. I decided to record the procedure and share my findings with the online dh community. I talked to Turner about the process before starting and received reassurances that they approve of the mod. Knowing how well Turner takes care of their customers, I gathered up my confidence and got out the drill and hacksaw.
My 06 Turner DHR w/ an 06 Marzocchi 888RC2X had a BB height of just over 14.5, this was w/ 2.5 tires and the fork as low in the crowns as possible. I wanted to lower the BB to 14. I talked to Greg & David at Turner and the Maxxis team mechanic about the proper offset for the second hole in the swingarm. For the BB height I wanted, an 8mm offset was required. Kircaldie runs his bike lower (mid 13) and uses a 10mm offset.
The mod requires two bits of work on the swingarm. First, the swinglink mount hole needs to be redrilled back (8mm in my case). Second, the material in front of the original mount holes needs to be shaved down for proper clearance of the linkage.
I started by measuring 8mm back from the original mount hole on the swingarm. I marked the spot to be drilled with a sharpie, and dimpled the center w/ a punch to keep the drill bit from wandering. I drilled the first side of the swingarm, and then used the little axle that the needle bearings ride on in the swinglink as a guide for drilling the second hole. This assured that the mount holes are aligned properly, and was a great tip from the guys at Turner. I found that it was necessary to shave some of the powdercoat to fit the axle further back from the original mounting holes.
The second phase required a hacksaw. I marked out the material to be cut from the front of the swingarm and went to it. My first cut was not quite the right angle, and did not give the needed clearance. I made a second cut at the proper angle and checked for clearance at full compression (remove shock spring etc). I then took a file and some steel wool to the cut part of the swingarm and cleaned it up. I ended up with a BB height of just under 14.
I am very pleased with the way the bike handles with the drilled swingarm. It took me very little time to adjust to the way the bike behaves, aside from needing to be a bit more careful about where I place my pedals. The DHR immediately felt more comfortable in steep technical terrain. Right after I made the mod, we went to a local race and I got a great chance to evaluate the changes in performance. This was a 3000 descent down old moto trails that were steep and full of deep ruts and loose rock. I was very impressed with how stable and comfortable the bike felt. I could let the bike run more than before, and I was surprised to find that the lower pedal clearance was less of an issue than I had anticipated. When I first started riding DHRs, I noticed that on steep tech trails I had to make an effort to shift my weight further back on the bike than I had in the past. This mod eliminated that feeling, and added a degree of extra confidence in those situations. I like the lower COG for cornering as well; you really feel like you are inside the bike instead of being above it.
After spending four months riding the modified DHR, I would recommend this procedure to anyone who rides in steep terrain. I have not yet found a situation where I miss the stock setting, although the mod allows for switching between the two mounts.
I would be happy to answer any questions about the procedure .
My 06 Turner DHR w/ an 06 Marzocchi 888RC2X had a BB height of just over 14.5, this was w/ 2.5 tires and the fork as low in the crowns as possible. I wanted to lower the BB to 14. I talked to Greg & David at Turner and the Maxxis team mechanic about the proper offset for the second hole in the swingarm. For the BB height I wanted, an 8mm offset was required. Kircaldie runs his bike lower (mid 13) and uses a 10mm offset.
The mod requires two bits of work on the swingarm. First, the swinglink mount hole needs to be redrilled back (8mm in my case). Second, the material in front of the original mount holes needs to be shaved down for proper clearance of the linkage.
I started by measuring 8mm back from the original mount hole on the swingarm. I marked the spot to be drilled with a sharpie, and dimpled the center w/ a punch to keep the drill bit from wandering. I drilled the first side of the swingarm, and then used the little axle that the needle bearings ride on in the swinglink as a guide for drilling the second hole. This assured that the mount holes are aligned properly, and was a great tip from the guys at Turner. I found that it was necessary to shave some of the powdercoat to fit the axle further back from the original mounting holes.
The second phase required a hacksaw. I marked out the material to be cut from the front of the swingarm and went to it. My first cut was not quite the right angle, and did not give the needed clearance. I made a second cut at the proper angle and checked for clearance at full compression (remove shock spring etc). I then took a file and some steel wool to the cut part of the swingarm and cleaned it up. I ended up with a BB height of just under 14.
I am very pleased with the way the bike handles with the drilled swingarm. It took me very little time to adjust to the way the bike behaves, aside from needing to be a bit more careful about where I place my pedals. The DHR immediately felt more comfortable in steep technical terrain. Right after I made the mod, we went to a local race and I got a great chance to evaluate the changes in performance. This was a 3000 descent down old moto trails that were steep and full of deep ruts and loose rock. I was very impressed with how stable and comfortable the bike felt. I could let the bike run more than before, and I was surprised to find that the lower pedal clearance was less of an issue than I had anticipated. When I first started riding DHRs, I noticed that on steep tech trails I had to make an effort to shift my weight further back on the bike than I had in the past. This mod eliminated that feeling, and added a degree of extra confidence in those situations. I like the lower COG for cornering as well; you really feel like you are inside the bike instead of being above it.
After spending four months riding the modified DHR, I would recommend this procedure to anyone who rides in steep terrain. I have not yet found a situation where I miss the stock setting, although the mod allows for switching between the two mounts.
I would be happy to answer any questions about the procedure .
lthumbsdown:
