I have 8 speed Shimano hub-geared bike. When I place the chain tug by geneticbikes.com, the black tud does not fit into the dropout. According to the thread, here, I can use one chain tug to the right without serrated anti-rotational washer and one anti-rotational washer to the left.

enter image description here The tud does not fit the dropout. I cannot understand where it should be in some hole but cannot understand the mechanics. What is the tud for? enter image description here You can see there the anti-rotational washer, being not round while the chain tug is round. enter image description here

I am unable to find the right position to the chain tug, apparently the black tud behind in the way. I tested and the tug is of the right size to fit the line but it is very hard to find the right position without tilting the chain tug, not found any position yet (not sure whether I need to round the tud to fit it.

enter image description here

[Update] After filing, how to protect the frame from the tug's screws? Tug on the right (chain's side) and the anti-rotational washer on the other side (recommend on the link below, not sure whether it is enough to stop the hub rolling).

enter image description here

You can see how the screws make bad to the frame, how to protect it? enter image description here

...and here is the picture on the right side, the anti-rotational washer is on the left side. The right side has no anti-rotational washer -- a problem? The fender screw is on the way to put the tug on a very good position, could the fender be placed on the same screw as the rack? enter image description here

Further information

  • same question but with incomplete answers here
  • moz explaining chain tug here, to protect the soft aluminium frame
  • chain tug to solve a chain slippage problem here

1 Answer 1


The extra stud would usually sit in the dropout slot and help align everything, but your dropout runs the wrong way for that so the stud is just an annoyance. File it off and things will work much better.

If the raised/recessed circle on the front of the tug is not big enough to accept the nut on the hub you may have to file that as well. It's visible in the bottom photo above.

update: you will probably be ok with only one antirotation washer, but ideally if you can get the tug in between the frame and hub so you can put the washer on the outside that would be better. Remember that the tug is now taking the force from the chain so the nuts don't need to be done up especially tightly. So you don't need full thread coverage on the nut.

  • you must be right, still trying to visualize to which kind of bike it is designed at the first hand.
    – user652
    Commented Apr 27, 2011 at 22:39
  • 2
    I have filed off a similar stud on at least one of my chain tugs. The wikipedia picture labelled "Horizontal rearward-facing track fork end (not a dropout)" shows what the chain tugs are designed to fit. en.wikipedia.org/wiki/Dropout_%28bicycle_part%29
    – Мסž
    Commented Apr 27, 2011 at 22:43
  • I filed the tud away, inserted one tug to the chain's side (right side) and one antirotational washer to the left side, not sure whether enough to stop rolling of the hub (just recommended in the link). The screws damages the frame. How would you protect soft aluminium frame?
    – user652
    Commented Apr 28, 2011 at 16:13
  • I can't see how you would, sorry. To sme extent you even want that - having a little flat spot helps the screws not gen bent sideways by pressing on the curve of the frame. I think just accept that there's enough spare aluminium that you're not really hurting the bike.
    – Мסž
    Commented Apr 28, 2011 at 22:22

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