Chain slipping while pedaling hard

[brandt]

Hello all,

I received my rad runner about a week ago. One issue I'm trying to resolve is to figure out how to get the chain to stop slipping when I pedal hard.

Thanks!

[sc00ter]

My 'Runner 1 has a random "jump" when I get on the pedals. I think its the chain tensioner bouncing around and not responding quick enough. Its a Sturmey-Archer if I recall, and I would love to find a better quality one. But the "jump" decreased as I got some miles on it so I'm not really worried about to now. But if anyone finds a better tensioner that works on a "Runner 1 please share!

[Wojciech]

@scooter - did you manage to resolve the issue? I've opened a ticket with Rad support regarding the same and wondered how it ended for you. I'll post an update when hear back from Rad, so far they've asked me for a video of the chain in motion.

[sc00ter]

Nope. I just put it down to the chain bouncing and the tension arm not reacting fast enough. So far my chain hasn't jumped off so its not a big concern, safety or reliability.

[Wojciech]

Thanks! And  has the OP? @brandt?

[handlebar]

My first few days, I thought the chain jumped occasionally. Then I noticed that while it happened only when I pedaled hard, it happened only at minimum torque: top dead center.

That's when i switch from pressing with my low foot to pressing with my high foot. When I pedal enthusiastically, my timing may be a little off, slowing the crank for a few milliseconds. Then my high foot drives the crankshaft forward, taking up the slack. The freewheel engages in increments that happen to be about the same as one link in the chain, so it can feel as if the chain jumped a link.

[bora]

I had a tensioner alignment problem. Chain slips were resolved after aligning.

[Calson]

Lack of chain lubricant can also cause this to happen. Can't hurt to use a dry silicon lubricant on the chain and see if it helps the problem.

[slayrider]

Purchased a Rad professionally assembled new Radrunner a week ago and am having the same issue. 

[Joel52334]

I've had a "clunking/slipping" feature when "tundra weather" finally left Iowa.  I received my RW4 in late 12/2020.  Our peak -30F weather.  It sat in the porch until mid-April.  The Battery stayed in my room.

I was frustrated with poor shifting.  I'm an RTFM "Read the fine manual" kind of person.  Videos are tedious.  As I read & re-read the manuals, I came to find the "derailer cage" was very bent, in shipping.  I didn't see a drawing showing the position of the cage.   Mine was bent in about 30 degrees, which was why I only had 2.5 gear changes. 

Once I got that fixed, with a big Channel-lock plyers (the blue handled 16" model).  I quit buying cheap tools a long time ago. Once I got the shifter fully adjusted & set, I discovered in that process I badly bent one link in my chain. It was deformed nicely.  UGGGG. 

I found my chain breaker, found & marked the bent link, removed the pins.  I was quite surprised the chain has no splice link.  That's kind of a PIA to do chain repair!!!  I was able to flatten the links on my anvil.  Found the pin that decided to hide under the tire (SH.t).   I mentioned this whole ordeal to one of the support staff.  I just noticed literally TODAY, there is a replacement chain, in my "order queue".  I don't recall being notified, but it's cool this was a warranty issue.

Just a thing to watch for is the derailer cage, which can be bent badly in shipping.  I'd like to ask RPB to add this NOTIFICATION, in the assembly instructions.  Oh, one more thing, they need to include that the chain should go UNDER the stand!

[keller09]

I was having the same issue. The chain guide wasn't out of alignment, so messing w/ that just made it worse. In the end, Rad Support told me to remove 3 chain links and replace with 1 master link. Hope this helps someone having the same issue in the future

[d0n]

Mine did the JUMP too. The bike is essentially "between gears" when it's jumping.

All you have to do is adjust the small adjustment wheel where the shift cable goes into the shift mechanism at the rear wheel. Back it out 1/2 turn or tighten is 1/2 turn. Try both and see what works.

[SemperVee]

After 1 week and 74 miles I had the same issue.   Kept fiddling with the rear deraillure adjustment and it finally is working as advertized!

[mbt]

The chain is skipping the rear cog on my brand new Radrunner as well.  Happens under moderate to strong pedaling forces.  My wife managed to get a video where one of the video frames clearly shows the chain lifting off the rear cog teeth and skipping over the the next valley.  The chain tensioner is not bent and is properly aligned to the plane of the chain.  Rather disappointing to have this happen on a new bicycle.  Its not like chain drive is a new thing and people are still figuring it out.

Anyhow, my feeling that issue is a combination of insufficient chain wrap around the rear cog and too light of chain tension.  Its easy enough to increase the tension by removing a chain link pair, but there is a finger on the chain tensioner mounting tab that prevents the amount of wrap being further increased past the current amount.  I'm still waiting to hear back from RPB on what they suggest doing.  With that said, I'm curious if anyone having this issue with a Radrunner or other single speed RPB have resolved this issue.

[mbt]

The chain is skipping the rear cog on my brand new Radrunner as well.  Happens under moderate to strong pedaling forces.  My wife managed to get a video where one of the video frames clearly shows the chain lifting off the rear cog teeth and skipping over the the next valley.  The chain tensioner is not bent and is properly aligned to the plane of the chain.  Rather disappointing to have this happen on a new bicycle.  Its not like chain drive is a new thing and people are still figuring it out.

Anyhow, my feeling that issue is a combination of insufficient chain wrap around the rear cog and too light of chain tension.  Its easy enough to increase the tension by removing a chain link pair, but there is a finger on the chain tensioner mounting tab that prevents the amount of wrap being further increased past the current amount.  I'm still waiting to hear back from RPB on what they suggest doing.  With that said, I'm curious if anyone having this issue with a Radrunner or other single speed RPB have resolved this issue.

So, I almost fully resolved the issue by grinding tab on the chain tensioner mounting flange to increase the amount of chain wrap and by removing a link pair.  Its not 100% fixed, but its pretty close.  It skipped only once or twice under very heavy load.  I'll probably grind the tab a little more to further maximize the amount of wrap.

I've decided that the root of the issue is the chain tensioner.  The tensioner pulleys should be much closer to the rear sprocket.  This would help greatly in keeping the rear chain pushed up against the sprocket.