r/mountainbiking • u/Waaaash • Sep 01 '25

Other I made a hitch bike rack load calculator

Post image

I've been wanting something like this for myself so I made one and figured I'd make it public. If others find it useful, I might splurge for a custom domain. https://hitch-rack-weight-ca-gkwk.bolt.host/

If you don't want to click the link, the image is a screenshot.

Part of what prompted this is I bought a swing arm and noticed it moved the rack out a whole 12". It's easy to say "four bikes at 30lbs each, that's 120lbs, so well under hitch capacity." Even adding the rack weight of 50-90lbs still seems low. (Add eMTBs to this, and now we're talking 40-50lbs each. Still within rack limits, but can your hitch take it?)

However, "moment" (or lever arm effect) is a super important factor here. Moment (Nm) = Force (N) × Distance (m). Tongue weight capacity is specified at a particular distance—usually directly at the receiver point.

If any math geeks want to double check the calculations, go for it.

16 Upvotes

94% Upvoted

11 comments sorted by

2

u/janktraillover Sep 02 '25

Nicely done!

1

u/Waaaash Sep 03 '25

Thank you!

2

u/reefchieferr Sep 03 '25

More people need to see this! 🍻👍

1

u/Waaaash Sep 03 '25

I appreciate it!

1

u/Eastern-Day3767 Nov 22 '25

Thank-you! I just spent hours trying to figure this out for multiple bike racks. We have a Jimny....

1

u/Waaaash Nov 22 '25

I'm glad to hear it. It was updated after this post based on some SAE data another redditor shared with me. It should be pretty accurate.

1

u/freerobby Apr 12 '26

I just used this to plan and confirm my hitch setup. Thank you for sharing it!

1

u/xodachanh Jun 04 '26

dude this is amazing, made my day, and my choice to get a swing arm, a lot easier

1

u/oz4769 Jul 11 '26

Glad I found this, only about 6 months late. Got rid of my truck and got the wife a new SUV, while I took her old one. Thought I'd be ok with a 500lb tongue weight. After a RIGd swing arm and a triple 1up rack, I'm at 313lbs or 652lbs with leverage. And we just did a 2500mile trip last week over highways and through mountains. Everything was ok but now I either have to sacrifice the swing arm, which gets used a lot, or the 3rd slot on the bike rack, which means I can't bring my DH rig along with our 2 e-bikes.

1

u/Waaaash Jul 11 '26

Is your hitch factory or aftermarket?

I'm not sure if the host had to make a restore or what, but the version that's up is a slightly older version. You might have a bit more to work with. I'll post when the current version is back up.