Need help: Chain rubbing on back tire & damaged derailleur screw on Tesgo STT

[antenando]

Hi everyone,


I’m hoping someone here can help me out with a couple of issues on my Tesgo STT e-bike (bought October 2023).

I reached out to Tesgo customer service about these problems 10 days ago but haven’t received any response yet, so I thought I’d try here.


1. Chain rubbing on back tire?

After fixing a flat on my back tire (no full tire replacement, just a patch), I noticed something odd: when I’m in first gear, the chain actually touches the back tire. In second and third gears, it’s super close—like less than a centimeter—but doesn’t touch. From fourth gear up, the chain-to-tire gap looks normal.


I’m pretty sure the wheel is mounted correctly because the washers and axle only fit together one way that makes the brake caliper line up right. The brakes are tight and don’t have any room for adjustment to fix the gap.


Is this normal? Should the chain ever rub the tire or be that close? Could it be a wheel alignment issue, or is this something common on the Tesgo STT?


2. Damaged screw on Shimano Altus derailleur hanger
While taking off the back wheel, I had to remove the Shimano Altus rear derailleur. It mounts on the metal derailleur hanger plate attached to the frame.


This hanger has two tiny screws holding the derailleur, and unfortunately one got damaged when I was trying to unscrew it. I took a photo and measured it—it looks like an M5 x 15mm flat countersunk hex bolt. Can anyone confirm if that sounds right? Or suggest where I can get a replacement?


Thanks in advance for any advice or tips. I’m a bit stuck and appreciate any help!


— Fernando

 

[any name you wish]

Hi everyone,


I’m hoping someone here can help me out with a couple of issues on my Tesgo STT e-bike (bought October 2023).

I reached out to Tesgo customer service about these problems 10 days ago but haven’t received any response yet, so I thought I’d try here.


1. Chain rubbing on back tire?

After fixing a flat on my back tire (no full tire replacement, just a patch), I noticed something odd: when I’m in first gear, the chain actually touches the back tire. In second and third gears, it’s super close—like less than a centimeter—but doesn’t touch. From fourth gear up, the chain-to-tire gap looks normal.


I’m pretty sure the wheel is mounted correctly because the washers and axle only fit together one way that makes the brake caliper line up right. The brakes are tight and don’t have any room for adjustment to fix the gap.


Is this normal? Should the chain ever rub the tire or be that close? Could it be a wheel alignment issue, or is this something common on the Tesgo STT?


2. Damaged screw on Shimano Altus derailleur hanger
While taking off the back wheel, I had to remove the Shimano Altus rear derailleur. It mounts on the metal derailleur hanger plate attached to the frame.


This hanger has two tiny screws holding the derailleur, and unfortunately one got damaged when I was trying to unscrew it. I took a photo and measured it—it looks like an M5 x 15mm flat countersunk hex bolt. Can anyone confirm if that sounds right? Or suggest where I can get a replacement?


Thanks in advance for any advice or tips. I’m a bit stuck and appreciate any help!


— Fernando

Fernando, welcome aboard. First of all the chain should never under any circumstances, and I cant stress this enough, touch the rear tire. It usually an alignment issue of either the wheel or the chain. Seeing that you damaged the screw that holds the derailleur it could be that the deraileur is not seated properly on the bike causing the chain to rub against the tire.

Take the screw to your local hardware store they could find a replacement for it if it is not some special specs. The remount the deraileur and see if that solves the issue.

 

[Chuy]

The missing screws should have no bearing on chain alignment. They are there to hold the hanger in place so the axle can slide in without binding or having interference with the hanger.

I would check that the hanger is not bent out of alignment. You can eyeball it from behind the bike to see if the hanger is bent. A derailleur hanger alignment tool is used to bend it back in place. Since the hanger is aluminum, it is susceptible to cracking. If no cracks, it can be bent back in place with the tool. There are videos on making your own tool. I wanna say RJ The Bike Guy has a good video on this.

 

[antenando]

Hi everyone,

Thanks so much for your advice and insights — really appreciate it!

I ended up taking the bike to a local e-bike shop yesterday, and the mechanic helped me fix the issue. He carefully unscrewed both bolts on the rear wheel axle — the one with the derailleur and the other side without it. It turned out the wheel wasn’t tightened properly: there was a little play looseness between the bolts, especially on the side without the derailleur.

He moved the wheel slightly to the right and down while tightening the bolts, and that properly seated the wheel. After that, the chain no longer rubbed against the tire. The washers were installed correctly all along; it was just this little bit of looseness causing the problem.

Regarding the damaged screw on the derailleur hanger, the mechanic told me not to worry about it — that bolt mainly holds the derailleur in place, but the axle bolts are what really keep everything tight and stable.

He described the whole process as “always a puzzle with only one way to fix it,” which I thought was a great way to put it!

Thanks again for your help — you definitely pointed me in the right direction.