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SLACKR Steel Mountain Bike
It was inevitable that once we created the SLACKR Titanium, the requests for a steel version would start to come in, so here you go! Enjoy!
Design Parameters: Build the most capable trail hardtail that is playful, grin-inducing, and built to pedal long trail days.
Introducing the SLACKR, our new 150mm/140mm travel shreddy hardtail that is designed for all-day trail riding. SLACKR comes in 6 sizes, fits a 36T chainring and up to a 29x2.6" tire. Fabricated using our custom blend of Velospec ELITE head-treated tubing tubing, our stainless steel Made in USA 3D Space Yoke, and PMW Sliding dropouts.
The SLACKR rounds out our MTB lineup with a slacker ;) option for riders looking for a playful trail bike.
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Chumba Custom Tubing: Built with Made In USA Velospec Elite HT tubing available.
The SLACKR stands out from other bikes in the long travel hardtail category with it's short adjustable chainstays and pedal forward seat tube angle.
This isn't another long travel park bike disguised as a trail hardtail. Our take on trail geometry positions the rider to be in a powerful all day pedaling position. This is accomplished through careful planning of reach and seat tube angles.
Designed to inspire confident play on the trail while the lightweight frame encourages you to ride longer.
Strong stainless steel PMW adjustable sliding dropouts and a 428mm - 448mm chainstay length offers 20mm of wheelbase adjustment fine tuning the bikes feel.
The reach is optimized for precise steering with stem lengths between 35mm and 70mm.
A balanced bottom bracket drop, positioned to bring out the rest of the geometry, gives clearance to pedal through technical rock gardens while also hooking up in cornering.
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Chumba Custom Tubing means this bike will exceed your expectations & provide years of reliable trail service. We create a frame that is tuned to you.
Paragon Machine Works stainless steel sliding dropouts for use with geared or singlespeed drivetrains.
Our 3-D Space Yoke chainstay yoke designed in house. Shaped for maximum strength & crank/mud/tire clearance. FEA strength tested.
S-bend seat-stays offer the perfect blend of compliance, traction & strength.
A custom bent seat tube brings together a short rear end, steep seat tube angle & maximum tire clearance.
Clean thoughtful cable routing w/ custom options.
Flawless frame miters and precision welds. All tubes are heat sunk and argon purged when welded to prevent distortion and material thinning.
Machined head tube for tapered or straight forks.
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The SLACKR mountain bike is designed to be extremely compatible with a wide range of tire sizes, hub options and fork lengths. Frames come with dropout inserts, rear axle and seatpost clamp.
Fork Travel: Optimized for 150mm - 140mm travel suspension forks. 44mm offset recommended.
Suggested Stem Lengths: 35-50mm
Frame Weight: Right around 5.5 lbs
Headset S.H.I.S.: ZS44 Upper/ EC44 Lower for 1.5” Tapered or 1 1/8” Straight Forks
Hub Spacing: 148x12 Boost
PMW Sliding Dropout Options: Geared, single speed, SRAM Transmission (your choice of inserts comes w/frame)
Rear Axle: 148x12x1.5 thread pitch (170mm total length) (comes with frame)
Max Tire Clearances: 2.6” on a 36mm rim
Bottom Bracket: 73mm Threaded External Cup T47
Chainring max/Chain-line: 1x 36T oval or 38T round on 51/52mm Boost chain-line, 55mm for SRAM Transmission
Seat Post: Post 31.6mm, can be shimmed for smaller posts
Seat Post Clamp: 34.9mm (comes w/frame)
Dropper Port: Reinforced stainless dropper port on non-driveside w/ silicone housing guide
Cable Routing: Standard cable routing goes under the down tube via PMW bolt on cable guides and then onto the chain-stays. (or options for custom routing)
H20 Capacity: 3 bottles on Sizes XL, L, & M, 2 bottles on small (or options for less)
Rack mounts: Old Man Mountain racks - a USA made thru-axle mounted rack that can hold up to 70lbs. It is more secure for the rack and cargo, and it better protects the frame than a traditionally mounted rack.
SLACKR Steel Frame Customizations
from $0.00
Frame Customizations
Customizations include HTL adjustments, internal routing, custom braze ons and more.
“All of our complete bikes are built with a custom selection of components. We pride ourselves on listening, understanding your riding goals & working with you to craft the perfect blend of components & customizations.”
SLACKR Steel Geometry Charts: Sagged & Unsagged in 6 sizes S - XL
150mm Fork Sagged 20%
| Measurement | S | S/M | M | M/L | L | XL |
|---|---|---|---|---|---|---|
| Suggested Rider | <5'7" | 5'7" - 5'8" | 5'8" - 5'10" | 5'10" - 6' | 6' - 6'2 | 6'2> |
| Suggested Stem Length | 32-50mm | 32-50mm | 32-50mm | 32-50mm | 32-50mm | 32-50mm |
| Effective Top Tube | 602 | 613 | 625 | 637 | 650 | 676 |
| Head Tube Angle | 65.8° | 65.8° | 65.8° | 65.8° | 65.8° | 65.7° |
| Head Tube Length | 95 | 95 | 100 | 105 | 110 | 130 |
| Effective Seat Tube Angle | 76.5° | 76.5° | 76.4° | 76.4° | 76.4° | 76.3° |
| Seat Tube Length | 15" | 15.75" | 16.25" | 17.25" | 17.75" | 20" |
| Chainstay Length | 420-440 | 428-448 | 428-448 | 428-448 | 428-448 | 428-448 |
| Bottom Bracket Drop | 65 | 63 | 63 | 62 | 62 | 58 |
| Wheelbase | 1163-1183 | 1175-1195 | 1188-1208 | 1201-1221 | 1214-1234 | 1250-1270 |
| Standover Height | 29" | 29.7" | 30" | 30.8" | 31.2" | 33" |
| Reach | 438 | 451 | 461 | 471 | 483 | 509 |
| Front Center | 743 | 755 | 767 | 780 | 793 | 828 |
| Stack | 629 | 627 | 631 | 636 | 640 | 654 |
| Est. Max Seatpost Insertion | 200 | 190 | 210 | 232 | 242 | 292 |
With 150mm Fork Un-sagged
| Measurement | S | S/M | M | M/L | L | XL |
|---|---|---|---|---|---|---|
| Suggested Rider | <5'7" | 5'7" - 5'8" | 5'8" - 5'10" | 5'10" - 6' | 6' - 6'2 | 6'2> |
| Suggested Stem Length | 32-50mm | 32-50mm | 32-50mm | 32-50mm | 32-50mm | 32-50mm |
| Effective Top Tube | 606 | 618 | 630 | 642 | 655 | 680 |
| Head Tube Angle | 64.5° | 64.5° | 64.5° | 64.5° | 64.5° | 64.5° |
| Head Tube Length | 95 | 95 | 100 | 105 | 110 | 130 |
| Effective Seat Tube Angle | 75.2° | 75.2° | 75.2° | 75.2° | 75.2° | 75.2° |
| Seat Tube Length | 15" | 15.75" | 16.25" | 17.25" | 17.75" | 19.75" |
| Chainstay Length | 420-440 | 428-448 | 428-448 | 428-448 | 428-448 | 428-448 |
| Bottom Bracket Drop | 55 | 53 | 53 | 53 | 53 | 49 |
| Wheelbase | 1175-1195 | 1188-1208 | 1201-1221 | 1213-1233 | 1227-1247 | 1262-1282 |
| Standover Height | 29" | 29.7" | 30" | 30.8" | 31.2" | 33" |
| Reach | 423 | 436 | 446 | 457 | 468 | 494 |
| Front Center | 753 | 765 | 778 | 790 | 804 | 838 |
| Stack | 639 | 637 | 642 | 646 | 651 | 665 |
| Est. Max Seatpost Insertion* | 200 | 190 | 210 | 232 | 242 | 292 |
Axle to Crown (A2C) Fork Measurements
Cane Creek Helm 150mm 29er fork, 44mm offset
A2C: Un-sagged: 563mm / Sagged: 533mm
Standover/Effective Seat Tube Angle
Standover is measured 90mm forward of the bottom bracket, using a 29x2.4 tire for reference.
Effective seat tube angle is calculated from average saddle heights and placements per size.
The range is roughly 1º in either direction of the effective angle based on your chosen saddle placement
Ordering
The SLACKR Steel 29er is available as a frame only, frame set, in complete build kits, and partial builds. Custom component configurations can be quoted on request here: Chumba Custom
You can order a SLACKR direct from Chumba over the website using the drop-downs on this page, over the phone, in person @ our Headquarters or from an approved Chumba Dealer. We welcome calls (512) 494-4944 and emails for immediate questions.