Recently, in the last month or so, I noticed that when I climb the two big (big for me) hills near my home, which measure about 18% or more on my Garmin, at the very top of the hill, as I am struggling to make it up the hill, the Schlumpf would slip. The combination of gears that got me up these hills is the lowest in the Schlumpf, SA BWR 3-speed and the lowest gear in the 2 external gears on Brahma. Brahma was built as a 6-speed (in the rear) Brompton P-Type with the Schlumpf Speed Drive in the front.
Knowing Schlumpf's reputation for bullet-proof engineering, I didn't worry about this much, but it was nevertheless bothersome, especially given I could lose my balance and crash, because of the instability brought about by the slipping of the Schlumpf.
So, it was time to dig out the Schlumpf manual and read-up.
The first thing that I noticed was that it was a good time to lube my Schlumpf. The picture below gives instructions for the same.
So, I hurried up and used my torx head to remove one of the 10 Torx screws on my Schlumpf.
This afternoon, I decided it is time to get to the bottom of things. So, I started my 3 stage troubleshooting process. My plan was as follows:
- Check the SA hub to make sure it is adjusted properly
- Check the Chain for tension and wear
- Check the Schlumpf for any play and rectify without making any major adjustments
Item # 3 in the list above is a very important step. Schlumpf recommend that you do not adjust the settings too much, especially if you do not understand how the Schlumpf works thoroughly. I don't claim to understand the inner workings of the Schlumpf in its entirety.
I did check the SA hub and it didn't need any adjustments.
Next was the chain on Brahma, which I replaced roughly a year ago, when I was in Dallas. I wrote about my experiences here and here.
When I checked the chain on Brahma, I was surprised to find that it had at least 75% wear on it. I checked the wear on a few links, before deciding it might be time to change it. However, I didn't think this was the problem, but I wanted to get a second opinion from a professional bike mechanic.
Anyways, I got in the Chevy and headed over to REI. Shortly, I met Ben. When we examined the Schlumpf together, Ben pointed out to me that there was some side-play in the Schlumpf, which was easy to adjust. Ben simply followed the instructions in the Schlumpf manual got it done**. Once the side-play was eliminated, I requested Ben to change the chain also. Luckily, REI had a 7/8 SRAM chain, which Ben assured me was equivalent to the 3/32 chain that was on Brahma. So, Brahma got a new chain as well.
**The adjustment needed to remove the side-play was the tightening of the part next to the bottom bracket on the non-drive side; this part is called a lock-out mechanism.
After I got home, I took Brahma for a test ride. I rode a short bit on a fairly flat road and then rode downhill to the bottom of the hill at Martins Road. From there, I rode up the hill, twice, in the same gear combination which would make the Schlumpf slip. Thank Goodness, no slippage. Phew!
I am hoping that the problem has been solved or as Clouseau would say, "Sol-ved" :)
I am very happy that I went to see a trusty professional mechanic.
PS. All along this process, Channell Wasson at Foldabikes, has been very helpful, by providing tips on troubleshooting. Thanks, Channell!
PPS. I found one of the Torx screws in the Schlumpf stripped. I know I did not strip the screw, by over tightening it, accidentally. The screw I removed to add lube, was not the one holding the trouser-guard in place. It must have happened, quite possibly when the unit was put together. I have found a temporary fix; replaced the stripped Torx screw with one from REI. The replacement does not match the color of the original and it is not of the same length; so, I have used a few washers to make it work for now. I plan to contact Foldabikes and Schlumpf Innovations and see if I can get a replacement. Hopefully, I can get a replacement from Schlumpf or Foldabikes.