Shimano XT group set buying options

hilbertspace

Hi all,

I made a thread previously inquiring about which brakes to purchase. It was commented that I could get a group set for the price I was prepared to pay, and after some thinking I've decided to go for it!

The first choice is between the M780 (3x10) and the M785 (2x10). Are there any other differences other than the crank set? I am currently running 3x8 and like three on the front. Are there any advantages to having 2x10 not 3x10?

Secondarily, the rear derailleur type. The choice is between top swing, bottom swing, E-Type, and direct mount. Is this choice specific to my frame or does each type have its own benefits?

Thirdly, teeth ratio (I think?). On the 3x10 the options are 11-32, 11-34, 11-36. On the 2x10 there are more options. I assume this equates to the variation in gears? If so, why not just go for the largest variation (11-36)?

All help greatly appreciated.

Sam

freshe

By the way if youre in europe merlincycles has some futher discounts on xt and xtr at the moment, you should also check bike-discount.de

supersonic

Larger spread of rear gears means larger steps between them, but wider range.

If you like the triple, stay with that.

freshe

3x10 gives you easier ratio on some hard climbs. The derailleur mount type depends on your frame mount option, clamps come with 3 different sizes but you should get spacers for the 2 sizes you didnt pick, braze on iuses mount that is a part of the frame, and the last one has something to do with the bb but its easier to figure it out when you see the photo of that derailleur. Top/down swing not sure whats the advantage-disadvantage of that. The bigger last number in the cassette ratio the easier (but slower) cycle. Never did mtb rides so thats all i can say here.

The Rookie

Bottom swing tend to be lighter but won't fit all bikes due to other issues like bottle mount locations.

F

The Spiderman

If you go 2 X 10 you really want the 36 tooth cassette.

thelonegroover

You don’t necessarily need an 11-36 cassette, just because you have 2x10. It depends on what the small chain ring and wheel size is.
On our 29er we had 38/24, 11-34,
on the 26er we had 42/32/24, 11-36.
The 29er was slightly too high geared, due to larger wheels, so I swapped the 11-34 and 11-36 over.

felix.london

I ride 2x10 but with an 11-32 cassette (22/36 chainset). I'm more interested in medium cage mechs than an insanely low gear

Saying that - my current AM/Enduro build is gonna be 2x10 with an 11-36 cassette (heavyish bike, slack angles and I have big, steep mountains to climb) so I'm having to go 22/32 on the chainset so I can use a GS mech on that too

thelonegroover

Right, a 22/32 combo = 0.688, 24/36 = 0.667, these are quite similar, however your planned 22/36 = 0.612, this is very low geared, especially on a 26er. (Maybe 10-11% higher on a 29er). In fact it's so low geared I think you'll just spin the back wheel on steep climb.

felix.london

Bearing in mind I'm doing some very big climbs. eg. I spent 3hrs climbing in my 22x32 lowest gear on Saturday. That's on my 12kg hardtail XC bike. I'm figuring with a 14.5kg Full-suss enduro bike with 180mm forks an extra 2 lower gears will be useful.

You think I could get away with a 11-34 cassette? - would prefer it as I could then have a bigger ring up front (34t)

thelonegroover

Yes, I would think a 34-22 fromt and 11-34 rear would work, that would give you 0.647 lowest gear.

felix.london

Thelonegroover wrote:

Yes, I would think a 34-22 fromt and 11-34 rear would work, that would give you 0.647 lowest gear.

Hmm...but there's no way to work out how these numbers will effect things out on the trail?

Sometimes (rarely but now and again) on the 'hopper I wish I had a lower gear so surely a heavier bike that's no where near as good a climber and has rear suspension will require a lower gear to get up the same hill with the same effort (or will the rear suspension act in my favour?..more grip on the back tyre?)

Don't really wanna fork out £45 for a cassette only to find I'm struggling on bigger, all day rides

thelonegroover

I wouldn't like to say.

Since I swapped the cassettes on our bikes, it didn't cost me anything. Also, my son, who's 14, can cope a bit better with the 11-34 than me!

felix.london

been debating what to do here for weeks and yesterday finally decided I go 11-36 and was about to order the cassette and now you've thrown a spanner back in the works!

This was my thinking (an insight into how my brain works) - an extra lower gear for the additional 2.5kg and an extra lower gear for the slack angles, longer fork & shorter stem...so 32 > 34 > 36...easy!

sofaboy73

felix.london wrote:

been debating what to do here for weeks and yesterday finally decided I go 11-36 and was about to order the cassette and now you've thrown a spanner back in the works!

This was my thinking (an insight into how my brain works) - an extra lower gear for the additional 2.5kg and an extra lower gear for the slack angles, longer fork & shorter stem...so 32 > 34 > 36...easy!

i'd prefer to have the extra low gear and not need it, than need it an not have it, especially in the alps.

if you go for 36 - 22T granny and think it is too low geared, just change your granny to a 24T (cheaper than changing rear block) and you'll have near as damn it same ratio as 22-34 in you lowest

hilbertspace

Thank you for the Merlin cycles tip.

There is no option for the rear mech type there but an additional option for the front mech:

Shimano XT M781 10 Speed Triple Front Mech - Conventional XT M781 10 Speed
Shimano XT M780 10 Speed Front Derailleur

Google has been unable to help with the differences between the M870 & the M781. The M781 description does include the word triple but I assume the M780 is triple too because it comes with the 3x10 groupset?!

Anyone able to shed any light?

Many thanks

felix.london

sofaboy73 wrote:

i'd prefer to have the extra low gear and not need it, than need it an not have it

That would obviously be sensible but I live/ride by Brian Lopes' words down there in my sig ↓

(so just ordered the XT 11-34 from CRC for £45 which tipped the order just over the £100 mark so a £10 discount came into effect, which kinda makes the cassette £35...happy days)

felix.london

hilbertspace wrote:

Thank you for the Merlin cycles tip.

There is no option for the rear mech type there but an additional option for the front mech:

Shimano XT M781 10 Speed Triple Front Mech - Conventional XT M781 10 Speed
Shimano XT M780 10 Speed Front Derailleur

Google has been unable to help with the differences between the M870 & the M781. The M781 description does include the word triple but I assume the M780 is triple too because it comes with the 3x10 groupset?!

Anyone able to shed any light?

Many thanks

Looks like M780 is top-swing and M781 is bottom-swing

hilbertspace

Shimano XT M780 10-spd front derailleur:
http://www.merlincycles.com/bike-shop/m ... lleur.html

Shimano XT M781 10-spd front derailleur:
http://www.merlincycles.com/bike-shop/m ... ional.html

The specifications above both state "Dual Pull design for use with top or bottom cable routing". Does that not mean that they can be top or bottom swing?

Many thanks,

Sam

cooldad

One of those is top swing, one is bottom swing - nothing to do with cable routing.

supersonic

No - swing is the position of the clamp. Top swing = low clamp. Bottom swing = high clamp.

hilbertspace

Thank you for your reply.

I'm told I need top swing (the m780) for my frame. Can you confirm this is correct using the pics attached?

Many thanks,

Chunkers1980

Looks like you could go with either.

Can't see any bottle cage bolt holes to get in the way.