Upgrading My Grand Canyon AL 6.0 MTB for Speed: Need Advice!
 

**Thread Title: Upgrading My Grand Canyon AL 6.0 MTB for Speed: Need Advice!**

Hey fellow riders,

I've been thoroughly enjoying my Grand Canyon AL 6.0 MTB, but lately, I've been using it more for fitness rides on roads and gravel paths. To optimize it for speed, I'm planning some modifications and would love your input.

First up, I'm looking to swap out the tires to ones better suited for faster surfaces. (probably Continental Race King)

Secondly, I'm considering upgrading the crankset to support higher speeds. Currently, I've got the SHIMANO DEORE XT HOLLOWTECH II MTB Crankset 2x11-speed with a 36-26 chainring setup. My idea is to replace the larger 36-tooth chainring with a 38-tooth one while keeping the smaller 26-tooth for those challenging uphill sections.

Has anyone tried a similar modification? Will the 38-tooth chainring work well with the 26-tooth one, or am I better off considering a different setup?

I'd greatly appreciate any insights or experiences you can share on this topic. Thanks in advance for your help!

36 to 38 is too small a jump to be worth changing, unless you are talking racing where tiny changes matter. The closer the chainrings are in size, the more duplicate gears you have, unless you are intentionally setting the chainrings up for "half-steps" i.e., percent changes that are halfway between cog changes. "Half-step-plus-granny" triples used to be popular on touring bikes, two close chainrings on middle and high, with a bailout low ring. The bigger the difference between the ring sizes, the less duplicate gears. Used to need to be 10 tooth, 52/42. Modern cranks can do at least 16 tooth spacing, and many go over that. The counter to that is if you want a certain size ring so that on technical trail riding you can avoid shifting in front, using only changes in cogs, easier.

If you make just the big ring bigger, then you might immediately be outside the max front difference that the RD can handle. If you make both rings bigger to be large enough to make a big difference in the gear ratios, then you might have issues with the chain stay clearance. As well your FD might be too low to adjust higher.

What year model do you have? They currently show a 1x front on that bike. Knowing what the exact model number of the RD will let you figure out what changes on the front you can make without going outside it's specs. For frame clearance and other stuff, it'll be trial and error for the most part.

Tires with a minimal tread pattern to them and better rolling will probably be the least expensive change.

This forum is about bike fit. Gear ratios are not about bike fit. You might get better responses if you post this in mechanics or mountain biking

Thanks for sharing your thoughts!

It's a 2020 model. I'll try to post the details of the components here.

What is your opinion, what specific product could I use to achieve the desired outcome?

Thanks for sharing your thoughts!

You need to tell us please:
- tire size
- cassette (cogs) range; Smallest and largest cogs at minimum
- rear derailleur brand and model (often will say on back, like RD-1234).
- front derailleur brand and model

With the above info, we can evaluate, for example, going as high as possible with the big chainring (so typically 16 tooth larger than the small chainring which you say you want to keep), while also seeing if the rear derailleur has sufficient capacity with a wide-range cassette, to accommodate more difference in chainrings. And, knowing the tire size, what such a change will yield in terms of gear-inches in high gear.

Here is what I've found on the manufacturer's website:

Tyre:
Original set
front: Schwalbe Rapid Rob 29x2.25"
back: Schwalbe Tough Tom 29x2.25"

New set (just changing)
Continental Race King 29x2.00" (50-622)

Casette
Shimano SLX M7000 11-42 11s

Rear Derailleur

Shimano Deore XT M8000 GS
Cage lenght: medium

Front Derailleur

Shimano SLX M7020

Here is what I've found on the manufacturer's website:

Tyre:
Original set
front: Schwalbe Rapid Rob 29x2.25"
back: Schwalbe Tough Tom 29x2.25"

New set (just changing)
Continental Race King 29x2.00" (50-622)


Casette
Shimano SLX M7000 11-42 11s

Crank
Shimano SLX M7000 36/26


Rear Derailleur
Shimano Deore XT M8000 GS
Cage lenght: medium



Front Derailleur
Shimano SLX M7020

I realize I haven't clearly explained my reasons and expectations for the change.

I've noticed that I'm reaching uncomfortably high pedal stroke on straight roads, which is becoming concerning. I have the power to handle a higher gear ratio, but I'm seeking a solution to manage this.

Primarily, I ride for fitness and enjoyment rather than competitive speed.

I also appreciate the geometry of this bike, which is why I'm considering modifications rather than purchasing a new one.

Thanks. OK let's unpack this.
Delta 31 teeth in back plus delta 10 teeth in front equals 41 teeth capacity needed for rear derailleur.
M8000-GS says 39 teeth total capacity (a surprise, my measly Shimano Tourney TX GS $13 RD has 45T capacity). So you are currently very marginal for the rear derailleur in terms of enlarging your gear range, front or rear. M8000-GS also says max front difference 10T, which you have.

Your current gear range is 17.9 to 94.7 gear inches. That's a great low, I don't think you need lower unless off-road on super-steep uphills; For a road bike, 17.9 is usually plenty low. 94.7 is also a good high, but if you want higher, what you need is a bigger front chainring, and 16T front difference is super common these days, that would give you a 42T chainring high. Plugging that revision into gear calc yields a 110.5 gear inch high, with excellent numbers through the range with a lot less overlap and duplicate gears. That's not a 120 race-high, but still pretty fast. That will bump your needed rear derailleur capacity to 47 teeth. A typical GS rear derailleur is rated for 45 and usually conservative, you could probably get away with that with a GS (mid) cage length (and preferrable for ground clearance) but if not enough capacity, a long cage should definitely work. However your front derailleur is only rated for 34-38T and 10T difference. So...

To get that higher gear range, you need:
- 42T large/high chainring
- front derailleur that can handle 42/26 (and pictures show your current FD to be one of those newer weird mounts, not road or band-clamp style, so you may need new FD to be same)
- rear derailleur that can handle 47T total capacity
- longer chain

Alternate option: Change the cassette to 10-42, that gives you 104.2 gear inch high, not as high, and you might need a different freehub body to accept a 10T small cog, not certain.

I'm not the authority on specific parts, others here are good at that, I encourage them to chime in.