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ShimanoUltegra CS-HG800 Cassette


Item # SHI00FY

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  • Gray, 11x34 ($97.99)
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Item # SHI00FY

Why We Like The Ultegra CS-HG800 Cassette

Ultegra might be the heart and soul of Shimano's line, and while we appreciate the precision, weight, and performance that goes into Dura Ace, we find Ultegra to be the perfect sweet-spot in the price-to-performance ratio. Shimano has created gear ranges in the Ultegra line for the most elite road cyclists to gravel grinders, and everything in between, so riders can achieve the sweet Ultegra feel no matter what they ride. In this particular iteration, Shimano creates the Ultegra CS-HG800 Cassette to fit on a mountain bike hub, so those running big touring setups or cross-bikes can now run the smooth shifting feel of Ultegra, and with the huge 11-34 tooth range you won't have issues finding the sweet spot to pedal your way through any adventure.

Shimano's experience in machining and engineering allows for exceptional amounts of technology to go into tooth design, shaping, and shifting ramps. Made from nickel-plated steel, the cogs themselves withstand corrosion and are tough enough to hold up to abuse, which leads to a cassette that stays smooth shifting and precise for longer than before. By opting for nickel-plated steel, it does add a bit of additional weight, but allows for a price that's much friendlier to those of us who have to shovel out our own cash for components.

To increase stiffness and improve shifting, Shimano groups the top five cogs as three and two, and rivets them to anodized aluminum spiders that add strength. The remaining six cogs remain as individuals, along with spacers between them, and a lock ring made of anodized aluminum to screw into your freehub and hold the assembly together snug. True to Shimano's Japanese culture—which has a name, poka-yoke, for built-in preventions of user error—one spline of the cassette is wider than the others and corresponds with the splines on the freehub, so the cassette cogs can only be installed with the right clocking of the shifting ramps, timing them for perfect chain pick-up and release.

The CS-HG800 comes in only one size, but has a large enough gear range to work for most riders at 11-34-tooth. With a gear range this large it's important to pair it with the correct derailleur, as it will not work with a short cage, and requires medium or long cage derailleurs to shift properly.

  • A MTB hub friendly cassette with Ultegra level performance
  • Durable steel that performs like Dura-Ace with a little extra weight
  • Available in 11-34-tooth cassette for huge gear range
  • Mountain bike compatible hub for HG freehubs
  • Precise engineering allows for smooth shifting
  • Exceptional dollar-to-performance ratio for great value

Tech Specs
Cog Sizes11-34T
Cog Materialnickle-plated steel
Carrier Materialaluminum
Manufacturer Warranty2 years

Actual Weight

Gray, 11x34

Claimed Weight

Claimed weights are provided by the vendor.

Have questions? Chat with a Gearhead


Actual weights are measured in-house by the Competitive Cyclist team.

Have questions? Chat with a Gearhead

What do you think about this product?



What is the recommended Shimano chain to be used with this cassette?

>Rating: 4

Great but...

I returned this product before using it
True to size

The ramp up on gears is too high... you loose out on a competitive edge on sprinting My fault alone for ordering this thinking it’d be the same as a 11-30


What type (width) of spacer is used on the 11/32 and the 11/34 cassette?

>Rating: 5

Much needed upgrade

I've used it once or twice and have initial impressions

I wanted to rebuild my wife's bike with premium components and this cassette was highly recommended by a friend. Installation was easy and now the bike feels much more suited for the steep grades in our area.


I have ultegra 6800 groupo, 11-28 cassette. With the proper cage and chain, will this cassette work?

My bike came with 11 speed long cage rear derailleur and 11-28 cassette. I had no problem replacing the 11-28 with this 11-34 cassette. I had to put in a longer chain though.

Yes it will, but you will need a long cage derailleur. I have exactly this set up, combined with a 50/34 chainring.

>Rating: 5

Great cassette nasty pitches

I've put it through the wringer

Nice to have a cassette where it doesn't matter where I go there is a gear for pretty much any pitch I will face. Typical Shimano quality.

>Rating: 5

34T Cog Helps on Steep Climbs

I've put it through the wringer

I ride in Colorado, which has steep hills at high altitude. There is cruel mountain road called Left Hand Canyon, which is 26 miles of relentless climbing that gets progressively steeper. The climb starts at 5,000 feet and tops-out at 9,000 feet. The last 3 miles is steeper than 12% grade. After the climb up Left Hand Canyon, I bought an 11-34T cassette. These two extra teeth on the big cog made a world of difference on steep climbs. I rode in the Triple ByPass ride, which is 120 miles over 3 mountain passes with 10,000 feet of vertical climbing. Those two extra teeth on the big cog made a real difference. I have included a shot of Loveland Pass, which is part of the Triple ByPass. Loveland pass tops out at 12,000 feet. Low gears really help. Even smaller hills seem flat with the 34T big cog. The only requirement is a long cage derailleur. My bike came with an Ultegra RD-8000 RD-GS that can handle a 11-34T Cassette. I didn't even have to change my chain. I recommend this cassette. Like all higher-end cassettes, this Ultegra cassette is light, durable and nicely finished. As mentioned before, on a road bike freehub you have to use the spacer that comes with the cassette.


Does this ultegra cassette fit on a 11speed road wheel free hub like all the other ultegra cassettes? I'm confused. I thought an 11 speed cassette doesn't need a spacer for a 11 speed free hub on a road bike wheel. If a spacer is needed does it come with the purchase of the cassette?


Yes, this cassette does include the spacer to adapt the freehub body to use this cassette.

It requires a spacer that is included. The large cog is dished so it can fit on disc brake mountain hubs that all still have 10 speed splines but dish out the larger cogs.

Stephen M, yes, this cassette is designed to work with a 1.8mm spacer on an 11 speed road cassette body.

>Rating: 5


This item allows us to use that nice 10 speed wheelset sitting in the corner because you bought a new bike with 11 speed. Shimano even thought of installation and tried to make it as easy as possible. The cassette comes packaged on a plastic alignment tool that slips on to your existing hub. Align the grooves and slide everything over to your hub all at once. Its literally that easy. I personally run this cassette on a SRAM Force 22 drivetrain with a med cage derailleur and 50/34 chain rings. It is super sweet and the 1:1 ratio made choosing a cadence while climbing so much better.

Hey Anthony, thanks for the review! Great feedback, much appreciated!

>Rating: 1

Defective product

I have had two of these cassettes. Both were defective. There is a problem with the spacing between the third largest sprocket and the neighbouring sprockets. There is not quite enough room, and so the chain constantly catches. This is either a design flaw or manufacturing defect.

this sounds like an issue of not using the spacer with an 11speed freehub body... that would cause shifting issues

Tim, are you able to take any measurements? If this is a spacing issue between cog clusters then some shims might do the trick.

I have had the same issue with two of these cassettes as well - one used on an 11-speed road hub and one used on a MTB hub. The included spacers are used, or not used, as directed by Shimano. The issue is exactly the same as described by Tim: when the chain is on the third-largest cog, it catches briefly on the neighboring cog with every revolution of the cassette. A quick search of the world wide webz will reveal that others have had the same issue. The cassettes are defective. That said, it is an annoyance, but does not cause the chain to skip or prevent it from shifting properly, at least in my case.

I just got this cassette, and have this same issue. In 3rd largest cog, there is a clicking/popping sound every revolution. I took a video that shows the sound here https://youtu.be/YHHSqxqM49k I am going to try and return it and go with the 105 version of this cassette (CS-HG-700).

I am having the same issue. Driving me crazy.

Hi Tim, I have this cassette as well and have tossed it onto two different wheelsets for two different bikes with zero issues (one is rim brake 11spd hub, one is disc brake 10spd hub). Thinking out loud, would changing to an 11 spd chain help to eliminate the issue? They are a bit thinner. I changed the chain on the 2x10spd bike when I installed this cassette. As I mentioned above, super smooth shifting. For reference, I am using SRAM Etap WiFli RD Mech, and an SRAM PC-1170 11spd chain on both bikes. Best of luck!

how do you know its not the chain? One misaligned pin could be the problem.

I have discovered the same problem


Where does the spacer go on my 11 spd road hub body? The diagram from shimano makes it seem as if it fits between the 11t and the lock ring. But I feel it needs to be the first thing on the cassette before the first cluster. any help?

Trust your instinct. Spacer is the First thing on the cassette hub body. The thing I’m Shimanos diagram between the 11t and the lock ring is the wave washer which, while removable, is usually attached to the lock ring.

Is this problem resolved? I'm thinking to buy this 11-34t to use with ultegra r8000 long cage. https://www.competitivecyclist.com/shimano-ultegra-rd-r8000-rear-derailleur Thanks! Paul