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Everyday fixes
Single-speed chain guide for bottom bracket
A chain guide keeps the chain from bouncing off the chainring on single-speed or 1x setups over rough ground. The guide mounts to ISCG05 tabs on a 73 mm bolt circle with three 6.5 mm holes, and its upper cage is 12 mm wide with 1 mm clearance either side of a 3/32 inch chain and a smooth 3 mm entry radius. PETG or nylon handle the chain slap, and a 3 mm plate with 2 mm fillets around the holes prevents cracking under bolt torque. Open the ready-made model free, resize it on your phone or computer, then download a print-ready STL, 3MF or G-code sliced for your printer, free.Opening the ready-made model and downloading it as STL or 3MF are free, no card; AI changes use credits, from Maker at $7.99 a month.No printer? We print this part and ship it to your door. See its priceUpdated
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Adjust
Change its numbers in the viewer for free, or ask the AI in the chat: wall thickness, hole size, the thing it clips onto. AI changes use 2 credits per request (1 for a quick edit, 3 for a redesign), paid with a plan from Maker at $7.99 a month.3Print
Download a watertight STL or 3MF free, with your numbers and hand edits, or G-code sliced for your printer at the same price. After an AI change the download is included in every plan (4 credits without one).
Dimensions of the ready-made model (editable)
| Parameter | Value |
|---|---|
| main plate thickness | 3 mm |
| ISCG05 bolt circle diameter | 73 mm |
| mounting hole diameter | 6.5 mm |
| number of bolts | 3 |
| edge fillet radius | 2 mm |
| standard chain pitch (approx) | 12.7 mm |
| radial clearance to chain | 1 mm |
| cage width (axial, along Z here as extrude thickness) | 12 mm |
| arc length of cage | 25 mm |
| radial thickness of the cage wall | 4 mm |
| entry radius chamfer on leading edge | 3 mm |
Example prompt
Create an ISCG05 chain guide with three 6.5 mm holes on a 73 mm bolt circle, a 3 mm plate, and an upper cage 12 mm wide and 25 mm long positioned for a 32-tooth chainring with 1 mm chain clearance, 3 mm entry radius and 2 mm fillets.
Fit notes
Chainring sizes change the cage radius, so SpeakCAD calculates the guide for your specific tooth count and mount type rather than making you sand a downloaded one. Adjust the cage height or switch to a BB-mount ring in the chat, and preview in the browser.
Questions people ask about a single-speed chain guide for bottom bracket
A chain guide keeps the chain from bouncing off the chainring on single-speed or 1x setups over rough ground. The guide mounts to ISCG05 tabs on a 73 mm bolt circle with three 6.5 mm holes, and its upper cage is 12 mm wide with 1 mm clearance either side of a 3/32 inch chain and a smooth 3 mm entry radius. PETG or nylon handle the chain slap, and a 3 mm plate with 2 mm fillets around the holes prevents cracking under bolt torque.
Click Open it free on this page and create a free account (no card): the ready-made model opens in your browser, on your phone or computer, nothing to install. Change its numbers in the viewer for free and download a watertight STL or 3MF free, or G-code sliced for your printer at the same price. An AI change in the chat uses 2 credits per request (3 for a redesign), and the download after it is included in every plan (4 credits without one). Start with Maker: 50 credits a month for $7.99, cancel anytime.
On this page: open the ready-made model free in a SpeakCAD account (no card), change any dimension in the viewer, then download the STL or 3MF free, or G-code sliced for your printer at the same price.
A shared STL is modelled for someone else's measurements. Here you open the ready-made model free, change it to your measurements in the viewer, then download a file sized for the part you actually own, free as STL or 3MF.
Yes. SpeakCAD slices the part on its servers with OrcaSlicer and your printer's official profile (380+ printers, including Bambu Lab, Prusa, Creality and Elegoo), and you download the G-code (a sliced .gcode.3mf for Bambu Lab printers). G-code sliced for your printer costs the same as the STL: included in every plan, free for a part you shaped by hand, 4 credits without a plan for a part with AI work in it. Pick your printer on the printers page to see its profile.
No. SpeakCAD runs in the browser on your phone or computer: the chat, the 3D engine and the live viewer load in the tab. The only file you download is the finished STL, 3MF or sliced G-code.
Print it your way
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