Easiest option for more gears?

handful

Hi all. I've recently bought a second hand Intense Spider 29er, lovely bike but I'm not strong on technical uphills and find I don't have enough gears compared to my old GT triple. It's an XTR 2 x 10 with 28/40 up front with a 36 the biggest gear on the cassette. Do I have any better gear options without spending an arm and a leg?

Cheers in advance

cycleclinic

fit a smaller chainring.

JBA

More gears won’t help. What you need is lower gearing fir the climbs. The easiest way to do that is to change the chainrings to smaller ones.
The version of XTR may limit which rings you can fit though (M980, M9000, etc).

handful

Thanks, anyone have an idea of compatibility with my crankset which I believe is an FCM985? Could I fit XT which appear to be available smaller?

handful

Been doing some research and it seems like the 28 is the smallest inner ring I can go with on the XTR 985. Which means looking at the back. I think I can go for a Sunrace MX3 but what size cassette will the XTR derailleur be able to handle? They do 11-40 right up to 11- 46 :shock:

I think even my poor climbing ability would allow me to avoid te largest option, I don't think I would be able to stay upright going that slow! If anyone has tried running 11-40 with XTR985 it would be great to hear from you.

steve_sordy

handful wrote:

Been doing some research and it seems like the 28 is the smallest inner ring I can go with on the XTR 985. Which means looking at the back. I think I can go for a Sunrace MX3 but what size cassette will the XTR derailleur be able to handle? They do 11-40 right up to 11- 46 :shock:

I think even my poor climbing ability would allow me to avoid te largest option, I don't think I would be able to stay upright going that slow! If anyone has tried running 11-40 with XTR985 it would be great to hear from you.

Your biggest gear at the back is currently 36 and you are contemplating a move to 40 to solve your problem; it won't! Going to 40 instead of 36 is only 10% easier, when the average shift between gears is 15%. To make a change that you will notice, you should go for the 46 at the back. That will be a 46/36 = 28% increase, which is still less than two shifts. But you will feel the difference. And you will stay upright!

handful

Thanks! Any idea what size cassette XTR will cope with?

handful

steve_sordy wrote:

handful wrote:

Been doing some research and it seems like the 28 is the smallest inner ring I can go with on the XTR 985. Which means looking at the back. I think I can go for a Sunrace MX3 but what size cassette will the XTR derailleur be able to handle? They do 11-40 right up to 11- 46 :shock:

I think even my poor climbing ability would allow me to avoid te largest option, I don't think I would be able to stay upright going that slow! If anyone has tried running 11-40 with XTR985 it would be great to hear from you.

Your biggest gear at the back is currently 36 and you are contemplating a move to 40 to solve your problem; it won't! Going to 40 instead of 36 is only 10% easier, when the average shift between gears is 15%. To make a change that you will notice, you should go for the 46 at the back. That will be a 46/36 = 28% increase, which is still less than two shifts. But you will feel the difference. And you will stay upright!

Ok, been doing some research and I now don't follow your maths steve_sordy!

How can the average shift between gears be 15%? With a 10 speed surely the average couldn't be more than 10%? Anyway, from what I can see the largest cassette I can have with the XTR SGS rear cage is a 42. I have 2 road bikes, one with a 28 and one with a 32 and there is a noticeable difference between them so I assume I would get a similar effect moving to a 42 from a 36?

kirkee

If im reading correctly your after better gear ranges for climbing as said above go for smaller chainrings, keep your cassette. A 22 36 crankset offers massive spread of gears when paired with an 11 36 cassette. If you check out the gear charts you will see what I mean. I use this set up and it works great. You can get the cranks https://www.evanscycles.com/shimano-deo ... 2-chainset as a complete upgrade or source the rings.
I have looked at the newer Shimano deore 10 spd mtb 2x bizarrely they dont have quite as good a range as the older 10 speeds. the newer ratios are based on a 11 40 cassette and 24 34 cranks v similar low end but with less top end and a larger probably heavier cassette. Im basing this set up as used on a 29er, gears will be a bit lower with 27.5 etc.

steve_sordy

handful wrote:

.................
Ok, been doing some research and I now don't follow your maths steve_sordy!

How can the average shift between gears be 15%? With a 10 speed surely the average couldn't be more than 10%? ......................

Gears are designed to be separated by the same percentage difference rather than by the same number of teeth. The steps are a geometric step not an arithmetic step. Obviously you can't have fractional teeth, so they go to the nearest whole number, which messes with the % step across the range, but the average across the range is the same.
An example:

Your current rear cassette is a 11-36. That gives a range of 36/11 = 3.273. You have a 10 speed cassette, so there are 9 changes to get you from 11 to 36. What % step is required? The answer is the ninth root of your range, ie 1.1408.

That is a 14.08% change per shift. That should produce the following:
11, 12.5, 14.3, 16.3, 18.6, 21.3, 24.2, 27.7, 31.6, 36

Or to the nearest tooth
11, 13, 14, 16, 19, 21, 24, 28, 32, 36

The designers have then decided to increase the 14t and 16t by one tooth to give steadily increasing steps in the number of teeth.

11, 13, 15, 17, 19, 21, 24, 28, 32, 36

Similarly the 11-40 gives a range of 40/11 = 3.636. The average % shift is 1.154 ie a 15.4% shift.

I have a 12-speed cassette with a 10-50 range, or 5.00. Eleven shifts will give me an average % shift of 15.75%

I won't do the sums any further, but you can see why I said cassettes have an average shift of 15%. It was decided many years ago that round about 15% was about right for bike gears. Yes there are exceptions, but mainly it's there or thereabouts.

handful

Thanks for suggesting another option but for me to replace my XTR chainset I would have to shell out an arm and a leg! Unless I can swap out the chain rings for smaller? I don't think there is an XTR crankset option smaller than 40-28 anyway. All I need to do (I think) is swap out my 36 for a 42 and although it may not be ideal it should give me a bit of a bail out gear for the cost of the cassette and a bit of fettling. I really just need someone to confirm if the XTR SGS will actually work with a 42? The gear capacity is within range, (40-28)12 + (42-11)31=43 and from what I'm reading should be fine but would be reassuring to know for sure!

steve_sordy

If you've done the cage sums then as you say, it should be fine. Don't forget to increase the length of your chain.