crank arms spinning with sbp jack shaft kit

skinnydog1_2007

skinnydog1_2007

New Member
Hi well I recently installed sbp jack shaft kit onto my GIANT UPLANDER SE mountain bike. What an awesome design these are. Have been riding it most days to work around 32klm's each way. Anyway today while riding it around at 43klm's p/hr the crank arms/pedals felt like it grabbed and scared me a lot at that speed. I checked that the chain was not lose on the jack shaft kit and was not rubbing on the bike chain. No plenty of room their so I went back to pedalling the old fashion just to be safe and see if it’s all ok. Yuck not into the pedalling thing anymore but now I noticed that when pedalling it would free spin for half revolution before grabbing then working properly. I went back to riding with the motor on ok for awhile but then it did it again the crank arms/pedals moved under my feet and seemed to do it more often. When stopping I noticed I could turn the crank arms around forwards and backwards easily. So I had to start pedalling again to get home seemed ok for awhile when I tried to start the bike the pedal/crank arms would spin with the motor and that's how I rode it home my legs out to the side while the crank arms were rotating with the speed of the chain drive. When i pulled in the clutch the cranks stopped rotating. I think my crank bearing could be mashed or the freewheel bearing has gone and is probably the cause of the problem I’m not sure will have to have a look. Anyone got an idea what it could be that has caused this???
 

Attachments

  • DSC00081.JPG
    DSC00081.JPG
    344 KB · Views: 1,460
Check/rebuild your actual bottom bracket, the "Crank Bearings" as you say- I bet this will remedy your issue.

Also did you use the crank spindle that came with your kit? If so, you would have had to break open and dis-assemble the bottom bracket and should remember what kind of shape your bearings etc were in.

Good luck, I also just built up an SBP shifter equipped bike and it is an awesome enhancement to my bike. It's essentially a micro motorcycle now, as I'm certain you are finding out.
 
huckersteve thank you for the reply. Yes i did use the bottom bracket crank spindle that came with my sbp kit. As my bike was an 2008 model the bearings looked good. I did not know what type of grade grease i was meant to use so i used car bearing grease. I hope this is not to thick a grade of grease to use and now my bearings have deceased because of this. Still have to have a look an see what the problem is.
 
Last edited:
Well that sounds fine actually- and that grease is probably a bit heavier and more viscous than bicycle assembly grease, but I imagine it's warm down there in Australia much of the time, no? I'd hope that heavy grease would still warm up after a while, but you DO have to pedal a bit to do that LOL. I suggest you back off the preload nut on the left side of the BB a HAIR, and re tighten the outer lockring, you should start to get better action out of your cranks. (hopefully!)
 
Pulled my crank/ lower bracket apart my bearings are still good. But my new 4 day old SBP JACK SHAFT kit is the problem. Their bearing in the free wheel crank arm round thingy is stuffed. It will turn in stops and starts but no longer has a click click sound but more the sound of sand from the beach. I wonder if unlucky me is the first to have this problem what a bummer !!! I will call them and see if it can be replaced under warranty. Do they have warranty on their kits? Anyway back to pubic transport for me yuck
 
Ah, so the freewheel for the new cranks is buggered? The Devil you say! (Sorry, I'm just trying to bring that one back- feel free to use it!) I'm not sure but I imagine the guys at SBP will treat you right, especially if the kit is new. You should call or email them directly.

Bummer, Brother.
 
Thanks for taking Steve's advice and contacting us via email. Yes your kit is under warranty and we will give you the options for resolving the problem to your complete satisfaction.

Paul
 
You must log in or register to reply here.
Back
Top