Originally Posted by jasonh
you don't want to drill all the way through the chainstay. Just one side of the tube, and use a sheetmetal screw. I would just do it on the bike so everything lines up.
For a new one, I've heard nothing but good things about the spring-loaded TSC one I linked to.
I would never recommending drilling through the chainstay one side or not - this is a tube (not a bar) and it's structural integrity will be seriously compromised by doing this. We've already compromised the integrity by attaching engines and drive trains to a pedal cycle that was not designed for it to begin with. I very much doubt that the screw idea would provide any defence against the turning moment exerted by a badly aligned chain or a badly attached chain tensioner bracket. The screw would just be pulled up cutting through the tube and destroying the bike frame. Some of those Walmart Schwinns have thinner chainstays than their more expensive cousins in the cycle shops and not only is the chain stay probably inferior but the tube diameter is too small for the tensioner bracket to be properly clamped. A poorly clamped bracket probably caused the accident to happen in the first place. Yes spring loaded tensioners are better but much depends on how the whole thing is set up and how good you are at getting it to the best possible alingnment.
If you stick with the stock tensiners that come with the kits I recommend always having the nylon chain guide at its lowest setting because the bolt is a stepped bolt and hard to replace with a non chinese-made one. We all know that the threads on these chinese bolts can strip and are really made from very mild steel. If you take enough care in getting it right you can tension the chain by sliding the bracket back along the chainstay. When you get too close to the rear sprocket you need to shorten the chain and move the tensiner further out along the chainstay. Usually you can stretch the chain in the first 300 kms and it won't stretch much more after that.
The spring loaded tensioner is best but the stock item can be made to work OK if you have the experience to follow the above guidelines. And yes it is a total piece of crud and a death trap because on the HT if the chain goes too slack it can get sucked into the chaindrive sprocket chamber where it kinks against the first corner and locks the back wheel totally (where the left hand top bolt goes) and send you on a trajectory towards the road in front. Beware of a slack chain on the HT and also of a too tight chain if you want to avoid serious injury.