Getting the bleeping rear cog off. Here's what I did ...
1. Clean the hub of as much gunk as possible before starting. I used dish soap, water and a rag ... but degreaser would have worked better. A wooden toothpick works well for cleaning the slots where the prongs of the removal tool insert.
2. Fasten the cog removal tool using a skewer. Make sure the tool inserts all the way into the slots (see picture). I chose to remove the skewer springs and attach it with the nut end of the skewer on the drive side. Including the springs might have been a better choice, as the skewer didn't remove as easily as it should have.
3. Attach the chain whip making sure as many links of the chain are engaged as possible. I used a large crescent wrench on the removal tool. At this point its all about leverage Despite me muttering "design flaw" several times, If you get enough leverage on the wrench and chain whip, in opposite directions, the cog will loosen. You won't believe it until it does, however.
Getting the necessary leverage ...
I had talked on the phone to a reader of this blog named Mark. Mark employs a two man operation using a hammer to remove the rear cog from a Rohloff hub. He didn't go into details, but I envisioned one person operating the wrench connected to the hub tool and another on the chain whip end. Not sure which side he hammered but I assume the chain whip side.
My first attempt mimicked Mark's method. With wife
bearing down on the crescent wrench, I wailed away on the chain whip handle with a large hammer. I continued hitting about six times beyond when the wife started complaining ... sorry dear. Fail number one. I needed more leverage.
Attempt two: I just happened to have a 16" long piece of 1 1/4" PVC pipe in the garage, and the crescent wrench handle just happened to barely fit inside the pipe. I was a bit concerned about the strength of the pipe, but the garage didn't yield any other options, so I went with it. Some sound advice: Never clean the garage.
Now, with the wife leaning all her weight (she's 5'2" by the way) on the PVC and me countering that weight on the chain whip end, the cog loosened with a gentle bounce of weight on my end. It seemed quite easy once we had enough leverage.
My LBS tried getting the cog off a few weeks ago. In a previous post, I stated concern that the mechanic had actually tried to tighten the cog. Fear confirmed. The slots on the hub, where the removal tool inserts, were damaged in a way indicating a tightening action. The slots were actually broadened so much that burrs prevented the cog from coming of freely. The cog actually cut threads into the burrs as it came off. The burrs had to be filed down before the Rohloff-Gates carrier would spin on. More sound advice: Don't let any mechanic work on a Rohloff unless they are experienced with the hub.
When all else fails, grab a cheater bar. When that doesn't do it, get a longer one. Repeat until successful or when you've ruined whatever it is you're working on.
ReplyDeleteha, ha. Much truth in that statement Bill. I originally looked for something to cushion my wife's hands, but the extra leverage came in handy and removed the cog without much grunt. The wrench alone might have been enough with tougher hands. Sorry dear.
ReplyDelete