[Closed] Jumbo Jim reviews please

To keep it brief, the 4.8 JJ is not as good as the Specialized Ground Control 4.6 in mud.

The only other Fat tyre I tried was a Kenda Juggernaut 4.5; but that was not the most challenging of conditions.

I'm awesome

😆

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I have the 4" ones mounted on 85mm rims. They are fantastic on loose or sandy trails, as above not as good in mud as a Bud but then they are only 1050g per tyre. I've got the snakeskin ones and I would strongly recommend you get that version. They don't self-steer like the Knards or Dillingers that I had before. Really superb tyres for what I use the bike for.

4.8 JJ on 90mm carbon rims, tubeless. Went up no problem, no burping.

Very light, supple sidewalls and run very low pressures no problem

Only used them so far on snow and while they do have a lot of float, the tread is not as aggressive and therefore grip on some less compacted snow can be sketchy. In fact I would say float aside, a 4.0 Floater or 3.8 Nate is loads better if run at low pressure.

I could believe al the comments about JJ's in mud would be true.

In the summer where I live, they will be ace on forest trails.

Just ordered some 4 inchers to compare to my current Bud/Bulldozer combo. Going on 65mm rims. Lighter, nimbler, faster rolling and less squirmy when cornering hard, I hope!

I'll report back...

if your trails are slightly muddy be prepared to suddenly find yourself on the ground on anything off camber, in the dry they are great though

nedrapier - Member
Just ordered some 4 inchers to compare to my current Bud/Bulldozer combo. Going on 65mm rims. Lighter, nimbler, faster rolling and less squirmy when cornering hard, I hope!

I'll report back...

Let me know how you get on....what are you're trails like?

rOcKeTdOg - Member
if your trails are slightly muddy be prepared to suddenly find yourself on the ground on anything off camber, in the dry they are great though

A summer tyre then....bummer, was ideally looking for something that rolls a bit quicker and lighter than my bud. Any other suggestions?

Well draining and sandy. The odd patch of mud here and there, but not enough to make mud performance much of buying factor.

I'm using a 4.8 on the rear, behind a Minion, formerly a bud. I'm really pretty impressed with it tbh, the 4.0 was pretty unpleasant with mud but the 4.8 while it slides and spins does it much more managably.

It depends on your mud, if you're pedalling uphill in deep mud then yes it's useless. But as long as I can make some progress, I like it, way more than I expected to.

We had a dry spell recently, so I whacked the 4.8" JJ on the front (was using a bud) - total game changer. As noted, not much cop in the mud, but then it's not meant to be a snow/mud tyre. It's not perfect though, suffers from some self steer.

Running mine on 65mm Carbon rims, nice rounded profile, acceleration and steering is very responsive.

Compared to the Surly offerings the JJ light years ahead in terms of quality as well, really easy to mount them straight on the rim, whereas I find the Bud a real problem.

A mate is running the bigger JJs on a Scott and isn't having any issues with them.

It's not perfect though, suffers from some self steer.

Just wondering how folks are getting on with these now that the trails are dryer. I've got the 4.8" version on my new ICT and while they are very fast they seem to give more "handling issues" than the Bud/Lou combination I tried on the demo bike. Not unsafe or anything, just the odd WTF moment as the bike seems to briefly do it's own thing. I'm guessing that this is what is meant by "self-steer" and looking at the tread it makes sense. The side knobs are much bigger than the central ones. So, if I'm running low enough pressures that the side knobs can grab bits of trail from time to time then it makes sense that they would self-steer, but most of the reviews I've read suggest that they don't!

Like the 4.0s I have. Really nice in dry conditions and noticeable faster than anything else I've used on the fatty.
Not encountering any self steer but I'm at 11psi rear and 9 front.

I'm running a jumbo Jim 4.0 on the back and it's a great tyre with a nate up front! Used it in both dry dusty trails and absolute slop fest! I find it a fantastic rear tyre and compliments the Nate up front superbly. I find it predictable as a rear tyre but wouldn't want to run one as a front in anything too sloppy of wet. The only issue I have is my tyre ocd of having different manufacturer tyres front and rear. But this is now my go to tyre selection for the fatty. I had Nate front and rear before but found it quite draggy. Still have the Nate sat in the garage if I find in the winter the jj struggles but from the wet root infested FOD it's been fantastic on the back end.

The thing that concerns me about the Jumbo Jims is that it look like it has barely any knobs (rubber) on it if you know what I mean? And they are spaced very far apart too, which makes me think they'd have a lot of rolling resistance, though I've heard the JJ have the lowest rolling resistance out of all fatbike tyres? Really confused!

Knobs have no effect on rolling resistance. Tpi tends to have more according the that rolling resistance website guy.

[url= http://www.bicyclerollingresistance.com/fat-bike-reviews/schwalbe-jumbo-jim-liteskin-2016 ]Here[/url]

3 month report -

faster? - Yes. Freewheeling on the road next to my friend on normal 650b 2.4 tyres (nothing mega aggressive or mega fast, std all rounder tyres) we were rooling next to each other, I didn't have to pedal to keep up. Quite amazed by that, but it was a science fact.

lighter - yes got the snakeskin version, but they were 90g heavier than advertised. bit miffed by that, but I'm over it now.

nimbler - yes, smaller/rounder profile, 1 psi more.

They might be a bit skatier in gloopy mud, but best for that is a cx tyre, so happy enough there.

officerfriendly - the knobs aren't significant when it comes to rolling resistance, when they're widely spaced, they're just another thing that deforms the carcass, like riding over a rough road surface - doesn't make much difference, the supple carcass takes care of it.

edit. started typing before I saw the above post. I thought about adding a disclaimer about not really knowing what I'm on about, but figured it all made sense, so I'd stick by it. Glad to see I wasn't far off the mark!

I went out for a ride around Whites Level and The Wall at Afan yesterday, rained all the time I was out.

Puddles everywhere, a very wet day.

Jumbo Jims 4.0 front and rear, no problem.

8 psi front, 9.5 rear.

I like them , now I have some confidence in them.

When it gets drier..... might put the Maxxis Mammoth on the rear to see how that compares.

Yeah right now I really like the 4.0s

Not saying they're better than the 4.8s they're just easier to thread through narrow gaps and have less bob. The bike feels less fat with them but I find them more pressure-sensitive than the 4.8s

Having said that the 4.8s were great over winter on Cannock's wet rubble so they'll be going back on when the weather turns

tubeless easy - yes
light - yes
skittish - Oh yes.
front - no

IMO - A summer rear tyre only.

I would never want something that unpredictable on the front, So for summer use I have left the Bud on the front. The JJ will come off when the days start getting shorter (that'll be tomorrow then!)

Thanks folks. These do seem to be pretty well liked and hardly anybody else is reporting problems with self-steer, which makes me wonder what's going on with mine.

It could just be that I'm not used to fatbikes. Maybe they all just give the odd bit of a wobble from time to time.

It could be the pressures I'm running (around 6psi on the front). I'll try upping that to 8ps and see how I get on.

It could be that I'm using 4.8" and most reports concern the 4.0" version.

It could be something else, unrelated to the tyres, but I can't think what.

Have not had any self-steering effects quite the opposite really it goes round corners like a motorbike

Just the occasional sideways drift when the wind catches them

What are the symptoms rp?

the only steering problem I had with mine was when I decided to drop a little pressure mid-ride before a very steep, scrabbly climb I'd never cleaned before.

I got up the climb, but had some steep, arse-over-the-back-wheel switchbacks after that, and I kept going straight on. Really low pressure and pretty much all weight over the front, plus breaking forces, all pull the front tyre into line, and there isn't enough rigidity in the tyre to transmit steering forces to the contact patch.

I knew I'd dropped too much, but measured when I got back, and I was down to around 5 - not enough! Not had problems with 7/8psi.

What are the symptoms rp?

Well, that's the thing, I'm not quite sure how to put it into words 😳 I was hoping that somebody else had issues with these tyres and could explain it better than me.

It's a sort of disconnected feeling. If I'm going round a corner it can feel as though it's gone straight on for a fraction of a second. Or maybe there is a hint of a tug to one side. Nothing extreme, but almost as if some unseen hand has given me the lightest of shoves. Also, if I'm standing up and starting a turn it can feel as though it's trying to stand itself back up again.

It's all quite subtle. If I'm riding anything technical or just riding at all aggressively I don't notice it. It's just when I'm passively rolling along and I guess I am sitting on top of two large gyroscopes!

Hmm there was something on mtbr about the (relatively) large area of tyre that's in contact with the ground giving rise to a 'rolling cone' effect but I can't say I've ever noticed it

Edit: here it is http://forums.mtbr.com/fat-bikes/what-causes-self-steer-887020.html

Thanks. Rolling cone effect makes sense.

It could just be that I'm being hyper-sensitive (new bike and all that). Maybe, once I've realised that these funny handling issues aren't actually dangerous, I'll stop noticing them altogether.

Snakeskin 4.0s fly on the tarmac near their max pressure of 30PSI compared to Mission Commands!

Really missed by commute by bike today, the weather was horrid this morning.