Problems up front: 2x10 vs 3x10 (advice on chainring sizes)

Kimbrorad

Hi guys, I hope this is the right place for this particular thread if not I apologise for being a muppet :oops: . This post is a bit long winded but please bear with it.... :roll: So after riding since October on my new bike (Norco Sight 3 SE running a full SLX groupset triple ring 22-32-42 and 11-36 out back) I have found I've been losing the chain quite often, to combat this I bought an SLX Shadow + rear mech and while this has helped with noise I still feel like I need some extra security (especially if I'm gonna be racing enduro this summer ) so I've been pondering changing to a double up front to simplify things a little and possibly add a light chain guide and bash guard (I've found even with the relatively high bb I still feel nervous attempting some more trialsy sorta moves and my poor 42 has sustained a bit of damage). My problem with this is I love to pull a big ring while offroad and I ride on the road a fair bit and the road behind my house gets steep and fast once I leave my house (my PB is 39.8mph ) and so I don't want to lose too many of those big ring ratios. My thought would be that I would ride a 26-40 (although I could be convinced to go 24-38 because you can pretty much stay on the 38 for most of the ride) up front but I have a few problems:
Firstly I don't know how I would mount the 40t because it would have to be a outer chainring running in the middle rings place and I don't know how that would work.
Secondly I'm not sure weather I need to just get fitter or when I ride my mind plays tricks on me because I always seem to end up in that 22/36 ratio and I don't know if the only reason I'm using that ratio is because I have it and I'm being lazy.
Thirdly I have been struggling a bit to find the those two chainrings (I've only been looking at shimano chainrings for two reasons firstly they seem to be the most bombproof and secondly I don't really know how compatible SLX shifters and dérailleur would be with other manufacturers chainrings).
I don't know how to calculate the ratios on bike gears and if anyone could either explain how to do it or just do the maths for me, if it helps I run 2.2 Spesh Purgatorys front and rear although people always say the specialized 2.2 is more like a 2.4 in (they have performed admirably if anyone was wondering!).
I am aware that the huge change in chainring sizes will have some drawbacks (mainly having to change gear at the rear to accommodate for the huge difference in ratio when I change up front but also because there is that big change that I will probably end up at least halfway down the cassette while in the granny at the front meaning I'll be cross chaining and causing some damage)
I'm not really trying to lose weight from the setup but I suppose any advice on that front couldn't hurt. I know my questions are a bit confusing and this post is horrendously long so anyone kind enough to give feedback I would be grateful to.
Cheers

Roostoids

Can't help with alot of your questions, but I'm considering going 1x9 or 2x9 as well. My reason being my front derailleur stuck in the middle ring a few months ago and I just never bothered fixing it, and didn't miss the other gears very much.

I think as long as you have the easier gearing option, in the back of your mind, you'll always be thinking "this hills killing me, change gear, change gear"!! When you don't have the option, you just carry on pushing the tougher gears. Might not make you a better climber but it does prove you don't 'need' all those gears.

I run an SLX triple chainring but as I said, am stuck in the middle ring. I managed Glentress, Cannock and Llandegla with only the middle ring, and there's plenty of ups and downs in such places. I think a 36 - 24 would be fine for me, your idea of a 40 tooth outer ring seems a little power crazed but it's all personal preference.

Personally I'd like to just get rid of the front shifter/derailleur altogether, all it seems to do is collect mud here in Uk anyway.

Giraffoto

Kimbrorad wrote:

<Kim's life story here>
I don't know how to calculate the ratios on bike gears and if anyone could either explain how to do it or just do the maths for me, <more of it here>

Each gear is <chainring teeth>/<sprocket teeth>, so a 36T chainring on an 18T sprocket is
36/18 = 2. Bigger number, higher gear. Use a spreadsheet program to make it easier. Some people like to multiply this figure by the diameter of the wheel, but it's not essential for the comparison

I'm looking at 2x10 too: 38/26 with an 11-32 cassette, which should cope with most situations

The Rookie

There is no escaping the fact that if you like pulling the 42/11 ratio (biggest/smallest), then right now (short of a mass upgrade to XX1) you'll need to stick with a 42 up front which realistically means a triple....

Giraffoto

This ^^^ is a good point - there's a limit to the front gap you can have without making the shifts between chainrings excessively large. And I've not seen any mountain doubles with a 42T big ring, although I'm sure they exist. SRAM do 39/26 cranksets, and Shimano offer 40/28, so you might just get away with upping your cadence.

njee20

you'll need to stick with a 42 up front which realistically means a triple....

28/42 works perfectly, and still gives you a pretty low bottom gear. If you want a 42/11 and 22/34 then you definitely need a triple, but there are plenty of doubles out there that'll provide a 42t.

jimothy78

Sorry for the hijack, but didn't want to start a new thread on so similar a topic:

I also want to go double, but more at the low end of things - (thinking 22/36). Slightly confused about the FD side of things. I've read you can use a tripple mech for double, just lock out the big ring position but techdocs for my FD-m590 states total tooth difference 22, minimum intermediate-higher difference 12T, which suggests to me a maximum lower-intermediate difference of 10T - have I assumed too much?

Also, to get more life out of the 36T ring I'm thinking of getting a Deore one(which I believe are steel) is there much difference between the M532 and the M510? - will one be the easier fit on an SLX crankset (I know it might involve some filing)

plugp7

jimothy78 wrote:

Sorry for the hijack, but didn't want to start a new thread on so similar a topic:

I also want to go double, but more at the low end of things - (thinking 22/36). Slightly confused about the FD side of things. I've read you can use a tripple mech for double, just lock out the big ring position but techdocs for my FD-m590 states total tooth difference 22, minimum intermediate-higher difference 12T, which suggests to me a maximum lower-intermediate difference of 10T - have I assumed too much?

Also, to get more life out of the 36T ring I'm thinking of getting a Deore one(which I believe are steel) is there much difference between the M532 and the M510? - will one be the easier fit on an SLX crankset (I know it might involve some filing)

Just go ahead and do what you've suggested. I've been running this set up for a few years with no problems.
As regards the M510 and M532 ring question. Basically the only difference I can see is that the shoulder the ring sits on is a greater diameter on the M510 than the M532. I got the M532 and had to file off a mill' or so to get it to fit. Just have a look at the images on the CRC site to see what I mean. There is more metal below the mounting hole on the M532 compared with the M510. Just compare these with what you have.

Kimbrorad

*update*
I've ditched my front chainrings and left myself with the 32 up front, taken off the shifter, gotten rid of the cables and fixed my derailleur in the middle ring position by use of the limit screws (as a very rudimentary attempt at a chainguide).....and, while its not ideal and I have dropped the chain A LOT it has given me an idea of where I am at in terms of gear ratios but I've decided to go with a simple 1x10 and guide set up for most days of the week and then for the cross-country rides I'll switch to the double. However I'm now facing another problem which is that I think I might have to buy a new crankset because I have found the chainrings I wanted but they are only compatible with the double ring cranks which is a real bore because cranksets don't come cheap!
Thanks

Kimbrorad

also I realise now that wanting a 40t might have been a little excessive...

Giraffoto

Kimbrorad wrote:

. . .I have dropped the chain A LOT . . .

You could probably do with shortening the chain

Kimbrorad

I have shortened the chain loads and I've got the shadow + mech but I still drop the chain.

Chunkers1980

Did you drop the chain when you ran a triple?

Kimbrorad

Not really dropped it, I stayed in the middle ring most of the time so if I was riding rough terrain it would tend to just bounce off the big ring or shift into the granny

JMcP92

Now - I must be fair, I didn't read anything but the title of this, so all my input is based purly on that:

I run a 3x10 on my bike, and as fun as it is, after a while I realise quite how unnecessary it is, doesn't matter what riding your doing, you tend to sit in the middle ring and play with the rearward gears and only move up or down on the front when something particularly challenging turns up, or you need top speed, both of which are not regular occasions.

Jist of all of this? Go 2x10

Chunkers1980

Why would you do that. Surely 3x is perfect for what you're saying. Middle: normally, challenge: granny, speed up: big ring

Going 2x would mean none of the benefits (less weight, only slightly smaller ring for clearence) and more changing at the rear especially if you try and keep the gears as unique as possible with a 14t difference.

YeehaaMcgee

Kimbrorad wrote:

Not really dropped it, I stayed in the middle ring most of the time

There's the main point here, I reckon.
If you're going to remove chainrings, you're going to lose some gears. So, stick with the range that you use most of the time, rather than gear the bike for the "outliers" of your riding.
Do you really "need" to pedal down steep hills? A steep hill will mean you pick up speed anyway. I can't think of a world cup DH racer that uses anything as large as a 42-tooth chainring.

And if you spend most of your time in the 42-tooth chainring (admittedly, you've already clarified that you don't), then you really need to start questioning whether you have the right bike for the job.