[bantam700]

I discovered on my ride today that my bike really doesn't like having a lot of force on the pedals while going up steep hills, there would be a loud pop coming from the back wheel area and the pedals would jump forward. The chainline is perfectly straight, the chain, tensioner, and both cogs are brand new, any idea what could be causing it?

[hophead]

Originally Posted by bantam700

I discovered on my ride today that my bike really doesn't like having a lot of force on the pedals while going up steep hills, there would be a loud pop coming from the back wheel area and the pedals would jump forward. The chainline is perfectly straight, the chain, tensioner, and both cogs are brand new, any idea what could be causing it?

Looks like you covered all of the bases. What size chain are you using? What kind of cog/freewheel & chainring?

[bantam700]

Rockwerks 16t rear cog, Surly 32t chainring , sram pc 1 chain originally 114 links but I had to shorten it.

[hophead]

I missed this the first time I read your post, but the pedal jumping forward sounds like a damaged hub. One or more of the pawls and/or engagement points within the hub may be worn or damaged. If so, you're probably looking at replacing the hub. If it's just gunked up you may be able to fix it by cleaning it out with a degreaser and re-lubing it.

This is probably not part of your problem, but an FYI: I'm not sure about the cog, but depending on which Surly chainring you are using, they recommend a 5-8 speed chain or a 6-9 speed chain rather than the 1/8" ss specific chain. I use a 94mm BCD 32t Surly chainring on my singlespeeds with an 8 speed chain. This combination has always worked well for me. The closer fitting chain causes less drive train wear.

[bantam700]

I hope it isn't the hub, the whole back wheel is new as well.

I wonder if it might be the chain tensioner, it has kind of a cheap feel to it.

[hophead]

Ohhhhhh, I didn't know that you were using a chain tensioner. I assume that you are talking about the spring loaded kind. That could be your culprit. It may be allowing the chain to ride up on the cog giving you that noise and pedal feel when the chain slips back down on to the cog. One possible solution, if that's the cause, is to try running the tensioner under the chain pushing upwards. That may or may not fix your problem, but worth a try.
An 8 speed chain will probably help too.

[bantam700]

After playing with it some I managed to replicate the jumping on my workstand/car rack, the chain kinda bounced off the wheel on the tensioner and got jammed. As the pedal kept turning top top part tightened and pulled the tensioner up and created a lot of slack on the bottom, the jam broke, the chain popped back on the gear and all the slack got taken up really fast.

Now if any of that made sense to anyone besides me I'll be surprised.

[Grape Ape]

Pardon my ignorance but why have a tensioner? Can't you just reduce the size of the chain down to a shorter length and pull the wheel forward and backwards to get it to it's final tightness? I remember my old BMX bikes and that is how it was done with them.

[hophead]

Originally Posted by Grape Ape

Pardon my ignorance but why have a tensioner? Can't you just reduce the size of the chain down to a shorter length and pull the wheel forward and backwards to get it to it's final tightness? I remember my old BMX bikes and that is how it was done with them.

You can if you have track ends or horizontal drop outs like a BMX bike. If you have vertical drop outs you are somewhat limited. You can either use a chain tensioner or an eccentric hub.

[Grape Ape]

Thanks never thought about the drop outs being anything but a slot that was horizontal, guess I never paid much attention. I learn something new every day whether I want to or not.