Replacing Acros Blocklock on YT Decoy w/Taller Lower Headset "Cup" SOLVED

[bmxmarty]

4/10/24 Edit - I was able to ditch the Acros headset and get fork-to-down tube clearance with no steering limitations. Scroll down to reply #14 for explanation and photos.

I know this is headset-related question, but I'm specifically wondering if anyone has done this on a YT Decoy, because the clearance won't necessarily be the same as on other brands/models. In my case, it's a Decoy MX CORE 2 in size Large. Tight switchbacks are hard to deal with because of the Blocklock headset, but I know it's there to protect the downtube and fork from hitting when turned close to (or more than) 90-degrees. What I want to do is replace the lower cup (willing to buy an entire headset, of course) with a taller one so I get the clearance without the forced stop. In the late 90's and early 2000's I worked at a Santa Cruz dealer, and when building smaller sized Superlight's and Juliana's I'd use a sealed bearing Primo (BMX company) Gorrila lower headset cup in place of whatever came stock on the bike to get the needed clearance for the fork. That headset cup was designed to be beefy, but a side effect was that it had a taller stack height. Obviously modern frames don't use traditional 1-1/8" press-in headset cups, but hoping there's something out there that will do the trick. Thanks in advance for any info!

 

[TommyC]

Others have just chipped away at the block with a dremel to give you more angle. Also, Acros do a 120° and 150° block lock. Keep meaning to check my cube and see if I’ve got the 120, then might just try the 150

 

[bmxmarty]

Ha! Yeah, good call on the Dremel! If there wasn't a clearance issue (there actually may not be, I can't turn the fork far enough to verify, so am just assuming) I'd be all over that. I know Wolf Tooth makes a headset cup extender, and that plus a "normal" headset (or Dremeling the Acros) may be the solution, but I also can't find exact headset specs for the Decoy frame to ensure I actually find the correct parts... Insert my retro-grouch "Bikes were so simple back in the day" comment here. Appreciate your input Tommy!

 

[TommyC]

I’m resigned to the fact I’m stuck with the acros. I need the stop as don’t have the clearance. I emailed acros the other day to ask how you replace the bearings. You can’t. They’re pressed into the cups and need to be replaced as a whole.

 

[bmxmarty]

Yeah I saw that about the bearings on another post too. I wouldn't mind getting a slightly slacker head angle and minor increase in BB height with a cup extender, in exchange for losing the steering lock. If I figure out what (if anything) works as a replacement I'll post it here.

 

[TommyC]

I guess if you go slacker you get more clearance from the frame?

 

[bmxmarty]

If you use a headset cup extender or a taller lower headset cup, then provided that the increase in cup height is more than the overlap of the fork and the down tube, you'd have clearance and as a side-effect, also a slightly slacker head angle and minor increase in BB height. For example if there's 6mm (as an example, haven't measured the actual number) of negative clearance (overlap) where the fork hits the frame, and you use a 10mm taller lower cup, then you should have 4mm of positive clearance versus the 6mm of overlap. Then you could ditch the Acros without worry of smacking the fork into the frame. This is assuming that the Decoy uses a press-in lower headset cup (which it looks like it does), because on a frame like the Heckler for example, the bearings sit directly in the frame without a press fit cup, so the extender isn't an option. Model and size of the frame, along with fork model will all play into the exact clearance number, so it's a bit of a case-by-case situation. But my hope is that it will work.

 

[TommyC]

Is this not what you need?

Wolf Tooth Lower Headset Cup Extender - ZS - Zero Stack

This Wolf Tooth Precision Zero Stack (ZS) headset features Enduro stainless steel bearings and custom designed seals is for frames with internal bearing cups. These lower headset cup extenders allow you to adjust the geometry of your bike frame by increasing the effective fork length by 10mm.

www.wolftoothcomponents.com

 

[wenna]

Is this not what you need?

Wolf Tooth Lower Headset Cup Extender - ZS - Zero Stack

This Wolf Tooth Precision Zero Stack (ZS) headset features Enduro stainless steel bearings and custom designed seals is for frames with internal bearing cups. These lower headset cup extenders allow you to adjust the geometry of your bike frame by increasing the effective fork length by 10mm.

www.wolftoothcomponents.com

Damn that pricetag though!

 

[bmxmarty]

Is this not what you need?

Wolf Tooth Lower Headset Cup Extender - ZS - Zero Stack

This Wolf Tooth Precision Zero Stack (ZS) headset features Enduro stainless steel bearings and custom designed seals is for frames with internal bearing cups. These lower headset cup extenders allow you to adjust the geometry of your bike frame by increasing the effective fork length by 10mm.

www.wolftoothcomponents.com

Yup - that is it. I just heard back from Wolf Tooth this AM to confirm the fit, because YT doesn't list spec details about the headtube. Using this should do the trick. Since it adds 10mm to the bottom of the headtube, I'll need to remove 10mm of spacers from the top, but overall bar height won't really change. I'll post back once I get it installed. Appreciate your input Tommy!

 

[bmxmarty]

Damn that pricetag though!

I just confirmed with Wolf Tooth that it's actually a full lower "Premium" headset assembly, complete with a race and a stainless bearing. So it's actually a great deal for what is basically half of a high-end headset, that also happens to be a solution to the Acros problem. Wolf Tooth calling it an "Extender" makes it sound like it's just a machined aluminum piece that goes between the frame and the lower headset assembly, which is confusing. Stay tuned for how this works out!

 

[E-MAD MALC]

I just confirmed with Wolf Tooth that it's actually a full lower "Premium" headset assembly, complete with a race and a stainless bearing. So it's actually a great deal for what is basically half of a high-end headset, that also happens to be a solution to the Acros problem. Wolf Tooth calling it an "Extender" makes it sound like it's just a machined aluminum piece that goes between the frame and the lower headset assembly, which is confusing. Stay tuned for how this works out!

Is your steerer tube still going to be long enough just a thought

 

[bmxmarty]

Is your steerer tube still going to be long enough just a thought

It is, I'll just need to pull two headset spacers out. That had been one of my first thoughts too, since bikes tend to ship with very few spacers and a pretty short steerer tube. Good looking out though, thank you!

 

[bmxmarty]

I got this resolved, and have decided to bore you with more details than you ever wanted. I replaced the Acros Blocklock headset with a Wolf Tooth, so now have no steering restriction, and the fork will not hit the down tube when turned 90-degrees. I really only needed the taller lower headset cup (the Wolf Tooth "Extender" as mentioned by TommyC), but decided to replace the upper headset assembly as well. I went for the Wolf Tooth "Premium" set-up (the lower assembly is also the "Premium" version, though they don't specifically say that), because I can't stand janky headsets, and buying a high-quality one generally means you never have to think about it again. Your bike spec could vary, so double-check with YT, but in my case for the YT Decoy MX CORE 2 in a size large (different frame sizes will likely have different levels of clearance) here are the parts I bought. Wolf Tooth part numbers are listed as well:

Upper: Wolf Tooth Premium ZS Headset - Zero Stack. Upper / ZS44/28.6 6mm Stack / Black. SKU: ZS44U-5MM-BLK.
Lower: Wolf Tooth Lower Headset Cup Extender - ZS - Zero Stack. ZS56/40 Lower Headset Extended 10mm / ZS56 / Black. SKU: ZS56L-40-BLK-P10.

As E-MAD MALC mentioned, adding 10mm to the bottom of your headset height means you'll lose 10mm at the top, so make sure you've got enough steerer tube length to be able to do this modification. My Acros top cap is 16mm tall, so I chose the 6mm Wolf Tooth top cap height option to exactly offset that. I'm still running two headset spacers under the stem, just as before. I am not using the Wolf Tooth stem cap with the integrated 5mm spacer, as I wanted the height under the stem, so just used a standard stem cap.

Both sides of the fork have ample clearance to the down tube, and the head angle should have slackened by less than half a degree. If memory serves, raising your front end by 25.4mm (one inch) will slacken your head angle by about 1-degree.

In terms of installation, you will need some pretty specific tools, so while you can MacGyver it without them, I'd recommend having a shop do the install unless you're capable and equipped with the proper tools. I was a mechanic for many years, so have the tools, and even still I managed to blow up the lower bearing during the removal process. That was not due to a lack of quality by Acros, it was totally my bad. I should have removed the upper headset cup first, to prevent the headset removal tool from being restricted by the inner diameter of the upper bearing, which meant it couldn't expand all the way. That caused it to sit on lower bearing instead of the cup, so it blew up. Here's the tools I used that were specific to the headset, you'll also need Hex and/or Torx tools to take your front end apart:

Park RT-2 for the lower cup removal.
Park RT-1 for the upper cup removal.
Park CRP-1 (link is for the CRP-2, as mine doesn't exist anymore) to remove the headset race.
Park CRS-15.2 to install the new headset race.
Park HHP-2 to install the new headset cups.

Thanks to the folks who chimed in on this post, I appreciate it!

 

[FixThatBike]

Thanks for this post! This is awesome info. I'm curious if you notice the bike handling any differently with the slacker head angle. I'd love to hear a report after you've gotten in a couple rides on it.

 

[as123]

Has anyone else experienced a very noisy block lock headset? I am considering replacing mine with this method. The stock decoy headset is very noisy and constantly makes cracking noises. I know it’s the headset because if I turn the bars so that it hits against the stop, it makes the same cracking noise. Very annoying. Has anyone else experienced this?

 

[bmxmarty]

Has anyone else experienced a very noisy block lock headset? I am considering replacing mine with this method. The stock decoy headset is very noisy and constantly makes cracking noises. I know it’s the headset because if I turn the bars so that it hits against the stop, it makes the same cracking noise. Very annoying. Has anyone else experienced this?

I didn't leave the stock headset in long enough for it to get noisy, but in many cases the headsets that come as OE equipment on bikes (even very expensive bikes), aren't typically very high end. As a result, they often get noisy and crunchy. Many people will say it's a waste of money, but in my experience, dropping Chris King money on a headset is always worth it if you're gonna ride a lot, ride hard, and/or plan to keep your bike for more than a year or two. My 2-cents.

 

[as123]

I didn't leave the stock headset in long enough for it to get noisy, but in many cases the headsets that come as OE equipment on bikes (even very expensive bikes), aren't typically very high end. As a result, they often get noisy and crunchy. Many people will say it's a waste of money, but in my experience, dropping Chris King money on a headset is always worth it if you're gonna ride a lot, ride hard, and/or plan to keep your bike for more than a year or two. My 2-cents.

Thanks for the advice. Ya I usually swap the oem headsets on my bikes as I’m pretty rough on them and I can’t stand the snap crackle pop they make in a carbon frame. I’m just wondering about the whole frame clearance issue on this bike. I am riding a medium Mx core 4, with a Fox 38 44mm offset I swapped on. Think the wolf tooth extender lower will give me plenty of clearance for a medium frame? What size is your decoy you did this on?

 

[Dirtnvert]

Thanks for the advice. Ya I usually swap the oem headsets on my bikes as I’m pretty rough on them and I can’t stand the snap crackle pop they make in a carbon frame. I’m just wondering about the whole frame clearance issue on this bike. I am riding a medium Mx core 4, with a Fox 38 44mm offset I swapped on. Think the wolf tooth extender lower will give me plenty of clearance for a medium frame? What size is your decoy you did this on?

I wonder if you could use a "reverse components" .5⁰ headset race in conjunction with the wolftooth? I think they work with most headset. It didnt work with my "works components" 1⁰ angleset but i think the angleset has a little something different going on with the bearing shape.
That would give you an additional 10mm rise of your headtube ,so 20mm total, and actually -.8⁰,with the wolftooth headset and reverse comp headset race, and raise your bb about 6mm total. Both not adjustments wouldnt be a bad thing on the decoy IMO.
I tried the reverse comp race with the works headset after ditching that arcos headset and hoping thst would give me that clearance on my medium mx decoy. Ended up just running the -1⁰ works headset and one offset bushing in the shock to slacken it 1.5 degrees and i havdnt contacted the crown on the downtube yet after 4 yrs but its possible. Im curious about the wolf tooth/reverse comp combo now my self. I shortensed my cranks to 160 but i wouldnt mind the at 155 and also have the bb a touch higher for pedalling through the rough. Rocky slow terrain around home here

Reverse Angle Spacer

Slackens head angles by half a degree (i.e convert a 65 degree head angle to 64.5) Aluminum spacer sits between the fork crown and headset on a tapered fork For use with headsets with 45 degree bearing race A slacker head angle makes bike more stable while descending 19g

reverse-components-usa.com

 

[bmxmarty]

Thanks for the advice. Ya I usually swap the oem headsets on my bikes as I’m pretty rough on them and I can’t stand the snap crackle pop they make in a carbon frame. I’m just wondering about the whole frame clearance issue on this bike. I am riding a medium Mx core 4, with a Fox 38 44mm offset I swapped on. Think the wolf tooth extender lower will give me plenty of clearance for a medium frame? What size is your decoy you did this on?

Hard to say if it'll work since downtube clearances may vary on different sizes. Mine is a large. YT should be able to tell you if a M has different clearance than a L to help determine probable fit.

 

[John_likes_bikes]

Hey all! New to the emtb world with the Decoy 29 I just picked up. I've been suffering pedaling up hills for waaaay too long ... Unfortunately I have to wait until Oct for it to ship so I have plenty of time to buy upgrades!

I'm looking to lose the block lock too, found this 15mm bottom cup option for any headset using a 45 degree bearing.

Niner Headset - ZS Lower Cup

15mm stack lower cup for Niner ZS headsets, AKA Slacker Puck - corrects geometry when using 27.5" Plus wheels

www.ninerbikes.com

Niner "Slacker Puck" lets you tweak your geometry at the headset...on any bike

For $20, Niner's Slacker Puck lets you make your mountain bike's head angle slacker and increase the trail, improving downhill handling on any brand bike!

bikerumor.com

 

[as123]

I just ordered the wolf tooth 10mm extender lower and a wolf tooth performance upper and going to do the swap on my size medium decoy when it arrives. I’ll keep you guys updated!

 

[bmxmarty]

Hey all! New to the emtb world with the Decoy 29 I just picked up. I've been suffering pedaling up hills for waaaay too long ... Unfortunately I have to wait until Oct for it to ship so I have plenty of time to buy upgrades!

I'm looking to lose the block lock too, found this 15mm bottom cup option for any headset using a 45 degree bearing.

Niner Headset - ZS Lower Cup

15mm stack lower cup for Niner ZS headsets, AKA Slacker Puck - corrects geometry when using 27.5" Plus wheels

www.ninerbikes.com

Niner "Slacker Puck" lets you tweak your geometry at the headset...on any bike

For $20, Niner's Slacker Puck lets you make your mountain bike's head angle slacker and increase the trail, improving downhill handling on any brand bike!

bikerumor.com

You likely considered this already, but make sure you've got enough headset spacers (guessing you've got at least 20mm, but verify before disassembly) to offset the fact that your effective headtube length is increasing 15mm with the new lower cup. Enjoy the bike!

 

[bmxmarty]

Thanks for this post! This is awesome info. I'm curious if you notice the bike handling any differently with the slacker head angle. I'd love to hear a report after you've gotten in a couple rides on it.

I haven't noticed any difference in handling, and I think even if I did, it would be minimal enough to be more than offset by being able to get around tight uphill switchbacks without having to do one of those trials motorcycle slow motion wheelie turns!

 

[John_likes_bikes]

You likely considered this already, but make sure you've got enough headset spacers (guessing you've got at least 20mm, but verify before disassembly) to offset the fact that your effective headtube length is increasing 15mm with the new lower cup. Enjoy the bike!

Good eye, I have. Without the bike in front of me it's a guess at the moment but for my preferred geometry I'd like to essentially keep the original stack height then +15mm, which may mean a new steer tube or CSU. Small price to pay to feel comfortable

 

[Dirtnvert]

Hey all! New to the emtb world with the Decoy 29 I just picked up. I've been suffering pedaling up hills for waaaay too long ... Unfortunately I have to wait until Oct for it to ship so I have plenty of time to buy upgrades!

I'm looking to lose the block lock too, found this 15mm bottom cup option for any headset using a 45 degree bearing.

Niner Headset - ZS Lower Cup

15mm stack lower cup for Niner ZS headsets, AKA Slacker Puck - corrects geometry when using 27.5" Plus wheels

www.ninerbikes.com

Niner "Slacker Puck" lets you tweak your geometry at the headset...on any bike

For $20, Niner's Slacker Puck lets you make your mountain bike's head angle slacker and increase the trail, improving downhill handling on any brand bike!

bikerumor.com

Boom! Great price too. Good one John

 

[as123]

Hey all, just did the swap on my Medium Mx Core 4. The block lock crown race is an absolute PAIN to remove. Other than that the swap is very easy. I installed the wolf tooth 10mm lower, and a wolf tooth performance upper headset. The new headset looks great, feels super smooth, clears the frame on both the damper and air side on my Fox 38, and no more noise! Definitely worth the upgrade. I’ll include pictures below!

 

[Dirtnvert]

Good stuff!!

 

[John_likes_bikes]

Hey all, just did the swap on my Medium Mx Core 4. The block lock crown race is an absolute PAIN to remove. Other than that the swap is very easy. I installed the wolf tooth 10mm lower, and a wolf tooth performance upper headset. The new headset looks great, feels super smooth, clears the frame on both the damper and air side on my Fox 38, and no more noise! Definitely worth the upgrade. I’ll include pictures below!

View attachment 144148 View attachment 144149 View attachment 144150 View attachment 144151 View attachment 144152

Is this an OE fork or did you upgrade? There's still a lot of steer tube left for the stack height. Looks to me that if it was factory cut that 10mm from the bottom wouldn't leave that much steer tube left up top.

 

[as123]

Is this an OE fork or did you upgrade? There's still a lot of steer tube left for the stack height. Looks to me that if it was factory cut that 10mm from the bottom wouldn't leave that much steer tube left up top.

Hey this is not an oe fork. I bought a core 4, but immediately upon receiving it swapped the Ohlins to Fox (38 and dhx2) and sold the Ohlins stuff.

Fortunately I like a long steerer, so I usually cut my forks with 3 10mm spacers under the stem. As you can see, adding the extended cup took away one 10mm spacer off the top. This Fork is cut right at 7 1/8 inch for reference , so it’s 0.625 inch longer than the stock 6 1/2 inch steerer that comes on a medium frame. 0.625 of an inch is roughly 15mm, so using the oe fork would work I think, just could only fit maybe a 5mm spacer under the stem. You could always swap out a stem with a low stack height (dmr defy for example) and gain some back though.