Schwalbe Jumbo Jim 4" Tire Thoughts

The Schwalbe Jumbo Jims are the second fat bike tire I owned. I wasn't particularly impressed with them - they didn't do great in the snow, and they didn't do great in the dirt. They were an OK compromise on both, but I'd rather have a tire that was great at something and mediocre elsewhere than a tire that's OK on everything.

The Jumbo Jim isn't a tire for expeditions and deep snow. It's a relatively lightweight and fast-rolling 4" tire. I want to see how this tire performs on technical singletrack with a Lauf Carbonara, and as a bikepacking tire.

Initial impressions are quite positive. The tire has awesome traction on dirt, and it rolls very fast. I took it on a quick run around Ruby Hill park, where I test every new dirt tire. My time on the loop was about as quick as with the 29x2.8" Terrene McFly tires. I credit the speed to the improved traction and cornering ability - the McFly's are nice, but the i29 rim doesn't suit them.

I'll be thinking on the following questions when I write a follow up review:
  • How do they work on groomed snow?
  • How do they work on singletrack? With a rigid fork and the Lauf Carbonara?
  • How do they work as a bikepacking tire?
Updated on October 24th, 2019:

Alright so I've used these a ton, but I've already swapped over to the Bud and Lou for this winter's snow, so I don't have any idea how they'd work on snow.

They work amazing on singletrack, even with a rigid fork. I never even tried them with the Lauf Carbonara fork - I never felt the need. A trail system on Green Mountain near Denver recently got an update to the Rooney Valley trail, which turned it into an awesome flowy downhill experience. I have better times on my rigid Mukluk with 4" tires than I do with my full suspension Jamis Portal with 29x2.35 tires, both in terms of enjoyment and actual Strava speed.

They work nicely as a bikepacking tire as well. I used them on Section 2 of the Colorado Trail over the summer, and the rigid bike performed admirably - climbing traction was superb, even on the loose kitty-litter parts of trails. The bike handled all technical challenges with ease, and it was quite fast on the level and downhill parts. The other two folks I rode with were on 27.5+ wheels, 2.8" and 3.0" WTB Rangers, and I had a noticeably easier time with traction.

There's a real good chance I'll be running these again next season. However, I've had a few issues with pedal strike - 26x4 is the smallest tire that the Mukluk can clear comfortably, and the lower bottom bracket really shows. I want to try 27.5x4 for next summer, but I may just go for a 27.5 front wheel. I may also just go for a 4.4" Jumbo Jim up front - that decision is a long ways away.

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