Juin Tech GT-P/Yokozuna Ultimo in hilly conditions

[Al]

Hello:

I just ordered some Juin Tech GT-P (which appear to be the same as Yokozuna Ultimo) brake calipers from overseas for an upcoming Black Mountain Road+ build. They seem to get uniformly great reviews (including being spec'd on Matt from Crust's bike: https://bikepacking.com/bikes/matts-crust-nor-easter/ and at the Path Less Pedaled: https://www.instagram.com/p/B0CFO2UHUjA/?hl=en). Does anyone have experience with these, especially in mountainous settings? I'm planning to use them on paved and forest roads in mountains around Los Angeles where 5,000 ft. descents are not uncommon. Do I need to be worried about the fluid overheating?

Al,

in Los Angeles

[David Kessler]

I'm riding Juin Tech R1s (same design but only dual piston) in Tucson. I've had no problems with fluid overheating but I was able to overheat the stock pads on a fast gravel descent on Mt. Lemmon. I swapped the pads out for Shimano XTR and have had zero problems since.

[John Bayley]

I use the Ultimos on a tandem (shod with 650B Velocity Cliffhangers and Terrene Elwoods, to keep things on-topic) and Motokos on a solo bike (with a variety of 650B rubber). Both machines spend the majority of their days on hilly, mostly dirt roads in western Massachusetts and other parts of New England. The brakes on the former are used in tandem (sorry) with Koolstop finned pads (http://www.koolstop.com/images/disc/KS-D640K.jpg) to maximise cooling possibilities and I have experienced zero issues. I would add the rider that descending style plays a large part in deciding how much heat a brake has to deal with, so YMMV. I should also note that I had to remove three fins from the outer pad to clear the cable housing stop on the Ultimo, the pads having been designed for hydraulic brakes which don't feature cables in that position. However, this takes all of 5 seconds with a decent pair of snips.

-- John

[Al]

Thanks! I'm coming from Velo Orange mid-reach rim calipers on my 700x35c bike, which do need quite a lot of sustained pressure paired with Shimano 105 brifters on dirt descents. So, not quite sure what to expect, modulation-wise.

Al, in LA