3 Chainring -> 2 Chainring move....

springtide9

Mostly ride XC, but have one bike that gets used for all - including trail centers 0 so need a bit of an all-rounder.

Components are all Shimano XT, probably 2006 ish I guess. Bike is Commie Super 4

At the moment, I'm running:

Front: Outer Chainring: 42T ; Middle Chainring: 32T ; Inner Chainring: 24T
Rear: 11-32t (or maybe its 34t) 9 speed. It was whatever was the most popular!

I hardly ever use the granny chainring - there are a few occasions when I may just want something a little big easier than middle + 32t (or maybe it's 34t), but if it wasn't there I'm sure I'd just man up'.

I am also in the market for a Bash Ring. Been shown a few local routes with lots of tree logs obstacles, but generally avoid then as my Commie Super 4 has a low chainring, and I like my chainrings the way they are (often take a bit of a bash)

So I'm thinking of moving from a triple to a double, increasing the size of the granny to the largest available, increasing the middle to also the biggest and swapping the outter for a bash ring.

Want to try and keep costs low as possible, and guess I can live with a triple shifter on the front, but with only two chainrings.

Anyone else done this? Recommendations for chainrings would be usefull, as well as any pitfalls,

Dirtydog11

If you want to keep costs to a minimum you could fit a steel Deore 26t granny and steel Deore 36t midddle and replace the outer with a bash.

http://www.rosebikes.co.uk/article/shim ... aid:415856

and

http://www.rosebikes.co.uk/article/shim ... aid:415844


If want to keep the weight down then fit alloy XT/SLX 26t granny and 36t middle rings.

http://www.rosebikes.co.uk/article/shim ... aid:349417

and

http://www.rosebikes.co.uk/article/shim ... aid:249911



I'd advise fitting an SLX 665 double front mech as it's specifically designed to work with a double and bash setup.

You will run into chain clearance issues with a triple front mech on a double and bash setup.

Good price here if you don't mind waiting

http://www.tweekscycles.com/Components/ ... 21/0/19564

or

http://www.tweekscycles.com/Components/ ... 21/0/19545


You will still be able to use you existing shifters without any issues

Northwind

Dirtydog11 wrote:

You will run into chain clearance issues with a triple front mech on a double and bash setup.

Unless you fit it right I ran an XT triple on a 22/36 double for ages, no bother at all.

cooldad

Ireplaced the big ring with a bash - no issues at all.

nicklouse

Northwind wrote:

Dirtydog11 wrote:

You will run into chain clearance issues with a triple front mech on a double and bash setup.

Unless you fit it right I ran an XT triple on a 22/36 double for ages, no bother at all.

+1 there are Zero issues.

The Rookie

Hard to see how there would be issues unless the bash was a larger diameter than the 42t outer (which it shouldn't be!)

Simon

Dirtydog11

@Thebegginer

It's the bash that causes the problems.

It makes it difficult to get the mech cage to sit low on the bash and not get chainrub.

In order to obtain the clearance the triple mech had to be mouted high which left a big gap between mech cage and bashring which is far from ideal for the purposes of chain retention.

I couldn't be arsed messing about with it and bought an SLX double, it now sits low, just over the bash with the chain securely enclosed, worked first time.

The easiest and most secure solution IMO.

Obviously not everyones experience :?

Northwind

The cage ends up at the same height regardless of whether it's a double or triple mech.

Mind you, the double is easier to set up, much more margin for error... And SLX double is lighter than xt triple. So not pointless, just not needed.

Dirtydog11

Northwind wrote:

The cage ends up at the same height regardless of whether it's a double or triple mech.

Mind you, the double is easier to set up, much more margin for error... And SLX double is lighter than xt triple. So not pointless, just not needed.

Have a look at the chain inner guide plate on an SLX double, its almost flat, whilst a triple has all sorts of specifically placed lumps and bumps in it to aid shifting, it's those specifically placed lumps and bumps that get in the way........................for me.

springtide9

Thanks all. Very useful.

Convinced on the swap out.

just checked and running 22/32/42 on the front and 11/34 on the rear; so little wonder why I hardly ever use the granny.

Looks like the largest on the granny is 26; and 36 on the middle - which looks pretty good looking at Sheldon Brown's Gear Calculator (http://www.sheldonbrown.com/gears/) - and can even do some fine tuning with closer ratios on the rear (later on).

Next question... I have Shimano XT M760 Chainset - looking at the options, it's really unclear what is compatible and what isn't.
I see Shimano appear to have changed the chain-rings over the years.. Is M761 the same as M760 in terms of comparability? Happy paying XT prices (or below) for the rings, as they are not that expensive (compared to a new chainset!)

Still looking at the front mech and trying to work out of the bash will fowl the chain. It does look like as long as the bash is no larger than the current 42t I should be fine.. but I know what these things are like when you fit them! I guess I take a chance!

As for the Bash.. are these any good?
http://www.chainreactioncycles.com/Mode ... elID=12167

As I already need to order a few bits from CRC, so if I can source everything from there

getonyourbike

Bash:
This = win - http://www.chainreactioncycles.com/Mode ... elID=19042
I wanted to support Straitline as aswell as maknig a great product they've done a lot for the sport. For example organising the Jump Ship event. They also have a different marketing strategy to everyone else, have fun and a laugh. Their April Fools 'product releases' are some of the best Quicky Stiffee, have a google

Dirtydog11

Any of the rings I linked to should work with your 760 chainset, I don't think you'll find a better price than those I linked to at Rose Bikes.

CRC are asking £27.00 for an SLX middle compared to £15.00 at Rose, even with delivery it works out cheaper.

Can't really comment on the bash other than a 36t would give you a tad more ground clearance than the 40t you linked to.

As for the mech, try your triple, if you run into problems you know what to do.

njee20

You can go larger than 26t on the inner ring. I ran 28/40 which was great. Check out TA Chinook rings from Starbike.com, cheaper than the UK and good availability. Smaller than a 42t is technically a middle ring, so it has different shifting ramps and what not, but I never had any problems.

An SLX double front mech is designed to work with a 22t inner, and has a tighter 'curve' to the cage - if you're running bigger rings I'd stick with a normal mech. I used XTR ones with no problems. You can use a road one which saves weight, but they do rub a bit more, and have a shorter throw. I had a Dura Ace 7800 which was fine with Grip Shift, but could be more finicky with triggers.

bails87

I use a cheap Shimano steel 38t middle/outer and a 24t inner. Gives a good range for XC/trail riding.

Shifting is done by a triple Deore front mech and triple X9 shifter, which both work fine.

getonyourbike

I'm also running 24/38T rings but from TA Specialites, like njee. I've got a triple XT front mech and X9 shifter. The bash ring is a trusty Straitline number

97th choice

Dirtydog11 wrote:

@Thebegginer.

In order to obtain the clearance the triple mech had to be mouted high which left a big gap between mech cage and bashring which is far from ideal for the purposes of chain retention. :?

Never had that problem, fitted a blackspire stinger and have 6" rear travel, no chain losses and chain slap is eliminated

Dirtydog11

97th choice wrote:

Dirtydog11 wrote:

@Thebegginer.

In order to obtain the clearance the triple mech had to be mouted high which left a big gap between mech cage and bashring which is far from ideal for the purposes of chain retention. :?

Never had that problem, fitted a blackspire stinger and have 6" rear travel, no chain losses and chain slap is eliminated

It depends what size bash you run, if you where to leave the mech in it's original position and fit a 40t bash there would be a smaller gap between cage and bash, it's not like you can just position the front mech wherever you want.

or are you saying you have a large gap between bash and cage but have not lost the chain?

ddraver

I use old 9 spd SRAM X9 with a 26 40 chainring for Holland XC/Cyclocross. I use the normal 3 x 9 mech just set up for 2, works fine. I only run out of gears when I'm approaching 40kph....

The only thing that took me a while to work out is that you can leave a big gap between the inner plate on the FD and the chain (on the small ring) as the FD will still shift out enough. This meand chain rub is less of a problem (although this won't work with a bash so I ve just wasted 4 lines saying it...hey ho!)

springtide9

Thanks all.

Decided to go for a 26/36 (M761 XT) | 11-32 (SRAM) setup with a Straitline Bash Ring/.

Looking at the front mech - there is not a huge amount of clearance between the rear suspension legs and the mech - there is probably only 3mm clearance between the 44t and the mech (and no room to move the mech any higher.

So this put me off going for a 38t middle with 38-40 bash (couldn't find any info on how much larger a bash is compared to a toothed ring) - so better to be safe than sorry as they say.
One thing that I found with the road bike when running a double, it that you do have to play around with the gearing to get something that suites - so think this was a good starting point.

I haven't run an SRAM cassette before on an MTB, but have been very happy with then on my road bike. It would be me, but I don't think SRAM is as 'clean' shifting, but it does seem to be less fussy with getting the cable setting right.
The problem is that all of my gear cables for the rear have been gummed up - so replacing the cables was also added to my shopping basket.

Thanks again, BR is an excellent resource for getting answers

Simon