How to measure for a replacement roller.
If you take three measurements from the old part — width, depth, and mounting-hole centres — you'll get the right replacement first time. Here's how.
- Steel rule or vernier (not a soft tape)
- Pen + paper
- A coin for scale photo
- 5 minutes
Typical bifold bottom roller
Get the part out — or get to the part
If the failed part still moves, take photos before removing it. Capture the orientation in the housing. If you can fully remove it without damage, do.
Measure A — width (longest dimension)
Lay the part flat. Measure end-to-end along the longest face, ignoring any soft rubber bumpers or end caps.
Measure B — depth (perpendicular to width)
Across the housing footprint, not across the wheel itself. This is the dimension that tells us which channel it sits in.
Measure C — mounting-hole centres
Centre-to-centre on the two main fixing holes. If there are 4 holes, measure both pairs and note both numbers.
Note the brand and a serial / cast mark
Manufacturer marks are usually moulded into the back face. Even a partial mark ("…SMRT 274") narrows it to a single product range.
Compare against the SKU spec
On any product page, the Specifications tab lists the same A/B/C dimensions. If yours match within ±1mm, you've got the right part.
- Don't measure the rubber. Bumpers compress — you'll always end up 1-2mm short. Measure the metal.
- Don't trust manufacturer markings alone. Smarts re-spec'd Visofold rollers in 2018 — same model name, different part.
- Don't guess on handedness. Take a photo of the door open from the inside, looking out. We'll confirm.
Still not sure? Email the photo + your three measurements and we'll match the part for you.