Chain slipping while pedaling hard

[Palpable8468]

Hi I have a new RadCity 4 that I think might be exhibiting this problem.

When pedaling, but not changing gears, it feels like there?s a bit of resistance, followed by a slipping/clicking feeling and sound, and then the pedaling becomes easier. It happened a few times on a short initial ride. It seemed to happen when I was changing incline and speed.

The bike fell over during assembly and maybe something was bent. It kind of looks like the chain is not evenly in the derailleur, but is grinding over the edge of it. I tried manually bending the derailleur outward so that the chain is seated cleanly inside, but I didn?t want to bend it too much since I don?t know what I?m doing and didn?t want to break it. And so it looks like it?s still misaligned.

Does it sound like this is the problem? Or is it something else? Is this something I could fix myself or do I need a repair shop?

Happy to provide any more info. This is my first geared bike.

[handlebar]

Hi I have a new RadCity 4 that I think might be exhibiting this problem.

When pedaling, but not changing gears, it feels like there?s a bit of resistance, followed by a slipping/clicking feeling and sound, and then the pedaling becomes easier. It happened a few times on a short initial ride. It seemed to happen when I was changing incline and speed.

The bike fell over during assembly and maybe something was bent. It kind of looks like the chain is not evenly in the derailleur, but is grinding over the edge of it. I tried manually bending the derailleur outward so that the chain is seated cleanly inside, but I didn?t want to bend it too much since I don?t know what I?m doing and didn?t want to break it. And so it looks like it?s still misaligned.

Does it sound like this is the problem? Or is it something else? Is this something I could fix myself or do I need a repair shop?

Happy to provide any more info. This is my first geared bike.

My only derailleur bike was a Six Three Zero that I shipped right back. There were two adjustments to keep it aligned through the gear shifts.

In your video, you're pedaling backward. I inverted my bike so I could see how the chain aligned pedaling forward.

[Palpable8468]

Does it sound like this is the problem? Or is it something else? Is this something I could fix myself or do I need a repair shop?

My only derailleur bike was a Six Three Zero that I shipped right back. There were two adjustments to keep it aligned through the gear shifts.

In your video, you're pedaling backward. I inverted my bike so I could see how the chain aligned pedaling forward.

Thanks. I ended up taking the bike to my local repair shop. They confirmed the derailleur needed to be adjusted. It cost $20 to fix, and I haven?t experienced the problem since they fixed it. They said if I?d kept riding like that it could have damaged the bike.

[rjp]

Send Rad a copy of the bill they might reimburse your money if under warranty. Contact them and ask it worked for me.

[Palpable8468]

Send Rad a copy of the bill they might reimburse your money if under warranty. Contact them and ask it worked for me.

Not a bad idea but in my case the derailleur was bent because I dropped it the bike during assembly!

[Sadrunner]

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.

Thanks for your story! I've never seen a chain tensioner/derailleur designed to be so far away from it's intended target. I may just replace the tensioner with an old derailleur.

[Radio Runner]

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.

Thanks for your story! I've never seen a chain tensioner/derailleur designed to be so far away from it's intended target. I may just replace the tensioner with an old derailleur.

Yes, somewhere in here I posted pics of doing that. You will need to tension the deraileur with a cable so it sits under the cog. Locking down the limit screw is not enough. Or you could call Rad and get the new idler they have now.

[Mooree]

The section at the bike's rear cassette slipping is the reason why the bike chain slips when pedaling hard. It could mean a problem with the rear derailleur's alignment, which needs to be adjusted. you will need to check the derailleur. if it is bent, you should straighten it into shape.

[Radio Runner]

Mooree,

You have revived a really old thread and I don?t think you have quite read it all. There was a recall with the Rad Runner chain idler that had nothing to do with bent hangers or derailleur alignment. It was a poorly designed idler that is no longer sold for over a year.