mtb: How many gears do you need?

[DavidF]

Not 27 or 30, that's for sure.

I am a recent convert to 1 x 10 drivetrains. For general purpose trail riding it's a great set up. I run a 34t chainring with a 36-11 10 speed cassette.

One of the issues with running single ring mtb setups used to be chain retention. You would need a chain device of some description to keep the chain on. Not anymore.

There have been two major innovations over the last year in this regard - cluch rear derailleurs and wide/narrow chain rings.

Clutch derailleurs have been around for a few years. The principle is that they have an extra spring which adds tension to the chain. I run a Shimano Zee http://www.chainreactioncycles.com/pl/e ... -prod82431 . As well as helping to retain the chain, because of the extra tension it gives much more precise shifting. Aslo because it's a short cage derailluer its more neatly tucked away under the cassette and hence less likely to get a knock.
The big breakthrough has been with wide/narrow chainrings. These were first developed by SRAM for their 11 speed XX1 groupset (stupidly expensive) http://www.sram.com/sram/mountain/family/xx1. The teeth on the chainring are a different design with alternating wide and narrow teeth giving much better chain retention. These are now readily available from other companys such as absoluteblack in the UK http://absoluteblack.cc/.

So what's my point - In my view this is a really good upgrade to your bike. How many gears do you need? Lighter setup, no front derailleur to worry about, much better shifting etc..For anyone wanting to try it that has a 9 speed setup - just buy the chainring and start from there..

[BrianM]

I will be going single ring setup on the trance once its current chain and cassette are beat out... Done it on the hardtail and feels so much better and saves a nice chunk of weight. After weighing all the gear that came off; the shifter and cable, front mech, two chain rings and bolts less what I put back on including a small retention device I saved 450g! Only just heard of those wide/narrow chain rings, I will also be installing one of these in the setup on the Trance for super sunday like climbing:
http://www.bikeradar.com/mtb/news/artic ... ook-39168/

[DavidF]

Yes, saw that 42t. You will also need a spare chain as it will need to be longer. And if you are using a short cage derailleur like zee then it may not work very well as the derailleur is designed for a specific gear range which the 42t will exceed.

There's also a crowd in Italy making a replacement for the top 3 sprockets on an SLX or XT 10 spd cassette, giving a 40t as the top gear - here it is:

http://www.i-mtb.com/general-lee-40t-ca ... r-shimano/

and a cheaper alternative to the 42t: http://www.ebay.com/itm/41-Tooth-Cog-fo ... 3cd81f6f31

[DavidC]

You will also need a spare chain as it will need to be longer.

A glimpse of the future...
Nice spring morning, big group tootling up Croghaun. Someone suggests heading for the mast. All agree enthusiastically.
Then McElwee pipes up, "Hold on there lads, I have to change my chain so I can use my 42 tooth granny cog."
First silence. Then unmerciful slagging. Soon McElwee is left alone with his chain tool and his thoughts.

[DavidF]

I was just waiting for DC to come along with the 'I'm happy in the Stone-Age' arguments

McElwee won't need his 42t cog cos he'll have turned into such a hard ba$tard from pedalling that 36t chainring of his he'll have legs of steel

[BrianM]

I was just waiting for DC to come along with the 'I'm happy in the Stone-Age' arguments

McElwee won't need his 42t cog cos he'll have turned into such a hard ba$tard from pedalling that 36t chainring of his he'll have legs of steel

Can't see any reason why I would need to change the chain, just a full lenght new one should do the trick..

Precisely Furlong, I may just go single speed and be done with it

[DavidT]

You can get slx or XT long cage derailleurs with clutches - "shadow+".