Surging/Slipping with SBP shifter kit?

Funny you mention the freewheel, I'm having the same problems. I bet you also feel it in your feet. At one point today , well it happened three times, my peddles started to spin and man, did that hurt. It also scares the crap out of you!
I don't think they were meant for all the pressure needed to start the bikes, otherwise I love it.

Well let me see if I can shed any light on the subjects mentioned, first dounuts31.

I can only speculate on the surging sensation since I can't touch or ride your bike. But that can't be related to the freewheel. When under power the freewheel is nothing but a bearing and can't slip. So that leaves just a few other options. You checked the clutch so that is probably not it. If you have the keys on your shaft then those gears shouldn't be slipping. You have a new rear cassette so I can't imagine that being the problem. The only thing I can think of is your bike chain. Does it happen only in the high gears or low gears? My thought is that your chains are touching. This causes a very similar sensation to surging or slipping. That would be where I would look first. When static you may think you have enough space between them but when riding your chains can oscillate and can touch. Here are two suggestions, first try spacing the chainrings farther apart. Second remove 3 or 4 links from your bike chain. You no longer have a front derailleur so you can shorten the chain. Shortening the chain will increase the tension applied by the rear derailleur and decrease the amount of chain oscillation.

toytime,
You are experiencing freewheel failure. I do not recommend you keep riding it. Send us an email and we can replace it for you. As you suggested starting the engine does put a lot of stress on the freewheel and some riders are more gentle when starting than others. However I have rode with my original freewheel for almost 2 years with no problems and I am sure you can imagine during all of the prototyping and testing I have started my bike more that most would in that time frame.

To be honest, I'd bet that I have everyone of the problems you mentioned. Like "donuts", I've already tore a rear derail-er to bits but I think that was my fault. It may not have been finished changing over to the gear I had switched to as I came to a stop sign and when I took off, it went flying into bits. With my new derail-er my chain tends to fall of and I can see that the chain is way to long. I'll just take a few links out. It's not a big deal. There's a real learning curve to these kits. It's amazing just how many things change with the jackshaft.

You mention the chains touching, that is a very good point and one that I will be looking at. I can see that happening and that could very well be what I think of as a "surge", where the bike seems to speed up and slow down. That was why I felt that we were both having the same problems. Maybe that feeling I felt on the souls of my feet was the chains rubbing!

My freewheel,
It just started acting up today and my first thoughts were that I should take it right off the bike and clean it well.I thought that maybe it has dirt in it.
I Guess maybe the part about the peddles starting to spin tells you that there is no saving it. If that is the case I'll get in touch with SBP.

Glad you offered that , it was very helpful.

The chain could be "flopping" around so bad that it's skipping a few teeth???
Is there a way to increase the tension on the derailleur??

I also use a mega range and I took 4 links out of mine. When in first gear my derailleur arm is pointing forward at almost 45 degrees but I have never had a problem and as soon as you shift into second it appears to be at a more normal angle. I would give it a try.

You may also want to check for seized links in the chain. Just go through the chain and make sure all of the links are supple and not sticking. A seized link can cause skipping.

I have experienced the same problem with the bike chain. I seems like it is "slipping". I caught it recently while pedaling the wheel on the stand to lube the chain. The chain would ride up on top of the teeth of the sprocket and fall back down. I experienced this under power and it would jerk severely. The problem was the derauiler was out of adjustment causing the chain to start to change sprockets and then fall back in place. I adjusted the derauiler and no more problems.

It does take some practice to diagnose things like the derailleur. Because it is being driven by the engine your only sense of it is through the seat of your pants. If you were pedaling and it did it you would feel it at your feet and know immediately what was happening.