Speccing to a price point
As Shimano's entry level groupset, we see a fair few bikes equipped with a Tourney gears and cranks. If you've not come across it, it comes in three flavours, Tourney, Tourney TX and Tourney TZ with Tourney being the most basic and generally 6/7 speed, Tourney TZ is a (decent) step up and 7 speed and TX gains another cog at the back and a little more sophistication in the shifting.
Still with me? Good. Unfortunately when you dive a little deeper, Shimano didn't always label the components 100% accurately so you'll see TZ and TX level derailleurs labelled as Tourney and bike manufacturers will frequently mix and match with different component levels on the same bike.
Which brings me to the point of this post... I've just had a Trek Marlin 4 in the shop and the owner has been complaining that whenever he does jumps or pops off the curb, the rear mech knocks into the cassette. Is there anything I can do to stop it happening?
The short answer is no, not really.
The Trek is a nice bike for the money. Sorted frame, a good weight, a pretty reliable Suntour fork... ok it's basic and a bit heavy but what do you expect? This one's a few years old so comes with V-Brakes, but when they're adjusted properly they work just fine - anyone remember cantilevers?
The thing is, it looks like a proper mountain bike but unfortunately it doesn't have mountain bike gears. Tourney is just not up to the job... I'm not expecting a fancy clutch mechanism for £15 but even a slightly stronger tension spring would help keep the mech out of the cassette a little better.
Excuse the cable fraying - I didn't replace that!
Plus, as it's the only 7 speed mech in the current range upgrading is an expensive process and is hardly cost effective on a bike like this. You might be able to source an old 7 speed Deore or XT mech but that's not something I'd try on a customer's bike.
So, in a roundabout sort of way, the point of this post is that for if you're looking at an entry level mountain bike and are expecting to ride it aggressively then check the gears. If it's Tourney then maybe save a few more pennies and go up a level.