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Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 3:16 pm
by DickieH
Hi all

I use my fatbike for bikepacking always in 29x3 guise. A mate is joining me next month (everything crossed!) With some others for a relaxed week in Scotland mainly double track and probs a third tarmac. 100km/day.

His OO Fatty wont take 29x3 apparently and he has tubeless 26x4" Jumbo Jim's at present and is a bit concerned about tarmac. Is it worth chucking 27.5x3 rims and tyres on for this? Money and faff of course. Or just perhaps a bit more air in the Jims?

I guess its 4" Jims vs. 3" WTB Rangers or similar.


My memory of Jims is they were good and fast, for a fat bike tyre! But I never rode them on tarmac. Any fellow fatpackers got experience of this comparison?

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 4:04 pm
by fatbikephil
I'd stick with the jumbo jims, just pump them up to 30psi and they run surprisingly well on tarmac and hard pack. I've run my 26 x 4.8's at that pressure for some long road miles and they have less rolling resistance than some full knob 29er tyres.

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 5:05 pm
by Alpinum
htrider wrote: Tue Apr 13, 2021 4:04 pm I'd stick with the jumbo jims, just pump them up to 30psi and they run surprisingly well on tarmac and hard pack. I've run my 26 x 4.8's at that pressure for some long road miles and they have less rolling resistance than some full knob 29er tyres.
Mostly what he says.

I too would stick to JJ, although I ran them at about 1.5 bar max, despite riding some tarmac during the beginning and end of a trip (was 26 x 4.8").

I completely agree, a super soft rubber compound with deep tread and sensible offroad pressure at 29 x 2.4" feels slower on tarmac than JJ and their sketchy pattern and hard rubber, no matter how fat.

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 5:45 pm
by ScotRoutes
How about a pair of 4" Husker Dus? Partly worn. I need to offload them so open to offers. Pics later if reqd.

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 6:02 pm
by DickieH
Ha, thanks, Jims are freshly on replacing Minions. I'm sure they will feel way faster than them.

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 6:41 pm
by Charliecres
Another vote for sticking with the JJs and pumping them up a bit

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 7:07 pm
by Alpinum
I always enjoy the faces when folks ask about the fatbike and I give them my bike for a quick spin.
Unless it's in soft snow, they're surprised to find how 'easily' it rolls.
They surely don't look as if they can, under certain circumstances, roll easily.

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 7:10 pm
by substandard
I used 4” jumbo jims for gbduro in 2019, ran em at around 14psi so it was still fun off road and it was perfect on tarmac.

After 2000km loaded there wasn’t much tread left though!

I did also do a 10mile road time trial on it in the run up to the event, averaged 23mph and beat a few who were wearing skin suits! Fun times

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 7:43 pm
by DickieH
Ha ha, great tale!

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 7:49 pm
by thenorthwind
substandard wrote: Tue Apr 13, 2021 7:10 pm I used 4” jumbo jims for gbduro in 2019, ran em at around 14psi so it was still run off road and it was perfect on tarmac.
I was going to mention this, but couldn't remember who it was! I regularly bring this up when discussing whether fat/plus tyres are draggy on the road. It seems the ultimate rebuke to the argument that they are... though perhaps not something everyone should try :lol:

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 8:21 pm
by Hamish
I have ridden miles on JJs on and off road. They roll just fine. A lot of the difference is in how the fat bike feels is in how it steers/handles rather than in the rolling resistance.

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 8:39 pm
by substandard
Loads of pics from gbduro on my Instagram feed, don’t know how to share the images on here

https://www.instagram.com/p/BznxqgUlXUg ... h0q1yyma3a

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 8:46 pm
by DickieH
I built up a 2nd wheelset for me with 29x3 Knards ... damn, now I'm wondering if I should use the 4.4 Jim's on there now, in fat solidarity.

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 8:50 pm
by substandard

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 10:15 pm
by fatbikephil
Heh heh great pic.
I was going to mention doing the Highland Trail on mine which involved much road riding on some steep hills, but I won't. Oh. I did... sorry....

Re: Fatpackers: 26x4 v 27.5x3

Posted: Tue Apr 13, 2021 10:50 pm
by Alpinum
DickieH wrote: Tue Apr 13, 2021 8:46 pm I built up a 2nd wheelset for me with 29x3 Knards ... damn, now I'm wondering if I should use the 4.4 Jim's on there now, in fat solidarity.
Better put on Maxxis Minions DHF in 29 x 3, ride them at 0.8 bar or else you'll stop believing what some are writing here :lol:

Re: Fatpackers: 26x4 v 27.5x3

Posted: Wed Apr 14, 2021 10:23 am
by fatbikephil
I was about to suggest fitting bud n lou and running them at 1psi for a real insight into rolling resistance....

Re: Fatpackers: 26x4 v 27.5x3

Posted: Wed Apr 14, 2021 12:30 pm
by substandard
htrider wrote: Wed Apr 14, 2021 10:23 am I was about to suggest fitting bud n lou and running them at 1psi for a real insight into rolling resistance....
Surly fat bike tyres at low psi are like Velcro on the road!