Issue with mounting brake caliper on Seaboard GR02 fork

[gbevan]

Hey everyone,

I'm in the process of building up a Seaboard GR02 frame, and I grabbed a Sensah SRX Pro hydraulic groupset that came with some iiiPro calipers: https://www.aliexpress.com/item/1005008682961574.html?spm=a2g0o.order_list.order_list_main.133.81591802Axg4MQ

The rear caliper went on absolutely fine, but I'm having a bit of an issue with the front caliper. From what I understand, the spacing on the fork for caliper mounting is 70 (or maybe 72, according to the Tsunami site) mm, and I can mount the iiiPro caliper no problem, but it's nowhere close to contacting my 160 mm rotor correctly. My initial impression was that I'd just need to grab a flat mount adapter for the fork, but I'm not sure I've been able to find one that would work in this scenario. I assume there's something I'm missing, but no adapters were provided with the groupset, so I figured I may as well ask here. I'd be happy to provide any more information if necessary, but for now I'm just scratching my head.

Cheers

[hsaus]

The GR02 fork has holes drilled with 20mm offset, so it can only be used with 160mm or 180mm rotors. Brake calipers set up to use 140mm rotors must be used with 160mm rotors, and calipers set up for 160mm rotors must be used with 180mm rotors.

I think the calipers you use are only meant for 160mm rotors on forks with standard caliper mount holes, so you'll need a 180mm rotor for this fork.

I had the same issue - I used Juin Tech F1 calipers, and they are also only meant for 160mm rotors.

[gbevan]

Thank you so much! This was my other hunch. I'll grab a 180 mm rotor in that case. Would you mind sharing where you found that there's a 20 mm offset for the fork's mounting points? Mostly for my own reference, but also in case someone else stumbles across this thread after running into the same issue we did.

[hsaus]

The Tsunami website for the Seaboard GR02 model used to specify 160mm/180mm rotors for the fork, but they've refreshed their website and I don't see it anymore: https://tsunamibicycle.com/product/gr02-gravel-frameset-alu-alloy-disc-brake-deep-grey/

[gbevan]

Well, now it's documented here at least.

[00Garza]

Well, now it's documented here at least.

Another reason this forum is unmatched. Where else could someone get this detailed help for an obscure issue like this?

[hubba]

Does the GR04 use the same fork as GR02? I got one coming and assumed the fork was 140/160 and got 2x 160mm discs. But after reading this topic now I'm wondering if I need a 180mm.

I'm using a flat mount to post mount 160mm adapter but put into a 160/180 mount it would still need a 180mm disc I assume. The seller didn't know just said rear 140 front 160 flat mount.