Tyre /rim setup for Hub motor to survive rocky single track

Hi Guys,

I currently have a leaf 1500w hub fitted to a 2011 Giant Reign (DS). The bikes been electrified for 1.5 years now and used for light off road duties and has performed flawlessly with a 2.0 Maxxis Larsen TT UST tyre with stans sealant. I've previously had a great run with in the past before fitting a hub- no punctures for 3 years / topped up sealant once.

I haven't ventured out to the rocky single track trails (Kalamunda) I used to ride frequently until this weekend. I forgot to bring my pump and started out with around aprox 25psi in the rear tyre. 1km later dented the rim (Alex Supra BH ->DH rim) on a rock / ripped the sidewall. Ok my fault I know I needed a little more air but I didnt hit the rock too hard Repaired the following day with a tube fitted with sealant, drove 45min back to Kalamunda, 750m into the ride pinch flat. Remembered why I went tubeless 5years ago......

So......

I'm thinking along the lines if I had ~38psi in the rear and hit a rock hard im inevitably going to suffer the same fate running a smallish 2.0 tyre?. Replace tyre with a heavy DH specific tyre and go back to tubeless? Is it just a case of needing to have a higher profile and thicker side walled tyre so there is more give? I want to know from people who are running similar weighted hub motors (~7kg) who ride rocky terrain hard, jumps etc etc what sort of tyre and rim setup are you running. Motorcycle rims arn't an option this is a bike Yes mid drive may be better and a 8kg wheel isn't the best for smashing into a rock but its been a pretty bulletproof setup until now and went well on the trail while it lasted

Mike

This is one reason I sacrifice performance, and run 65 psi. I've done the walk of shame home a few times from our rocky trails, after a good pinch flat. At least its all down a steep hill back to the car, but it's about 4 miles of hike from where the rock staircases are.

Because of the 2" long thorns everywhere here, I run as big a rear tire as I can, minimizing the thorn going in the bottom and out the top. Thick tubes and tons of sealant, because I may be running with 100 or more thorns of less length in that tire. Higher pressure keeps the short thorns from going through and through.

Bottom line, for me, it's always carry a pump, and keep it hard, mostly because of all those thorns. If I blow out half my sealant, I can at least get it back up from 15 psi.

I'm riding in similar conditions (although not with a hub motor).
I would definitely recommend a tubless setup. The "ghetto" tubless conversions can work as well as "original" tubless setups if not better, every different tire/rim combinations works best with a different conversion according to how tight the tire is on the rim.

For rocky terrain when weight isn't really a concern a DH type tire is best; 2.4"-2.5" width, DH (dual ply) casing, for the rear, a lighter casing is sufficient on the front. As for thread pattern, I have good experience with Maxxis Minions and High Rollers in a long lasting hard compound in the rear (60a) and softer tackier fronts.

Running 28-32 PSI in the rear and 24-28 in the front.

Avner.

Dan: Guess i'll try increase the pressure but it does make the rear end harsh. Going to purchase a 2.3 minion dhf or similar and give that ONE more try otherwise the hub goes. Not as if i've babied this hub in the past with what its taken but as soon as sharp rocks are thrown into the mix *ka-poof* twice in a row!!
Sound like nasty thorns!!!!! I thought our double-g/Goat head thorns were bad. There in plague around where I live, running a sealant is the only way to go!

Avner: Thanks for the tips. I have mountain biking experience with what to run but the main problem here is a big hunk of weight in the rear wheel smashing into sharp rocks and the tyre/wheel absorbing the impact before the suspension does so to speak.

Seems like if the pressure is low enough to allow a pinch flat, you'll pinch flat. All my pinch flats happened before I carried a pump. those thorns would let some air out, then blam.

Mesquite has some nice thorns.

Why then go to 2.3" instead of bigger?
The bigger the tire the more cushion you will get.
Whatever size you decide on, make sure it has dual ply/DH casing, that will give you the most protection from sharp rock.

By the way the newest technology is a dual chamber setups (see below), but I believe that a burly tubless setup is almost as good unless you are racing.

Schwalbe Procore: http://www.schwalbe.com/en/schwalbe-procore.html
Deaneasy: http://www.deaneasy.it/en/
DIY: https://www.youtube.com/watch?v=OlrvET4BgN0

Avner.

Pinch flats are a symptom of a much larger problem. Ditching tubes for tubeless setups because of pinch flats is reactionary and doesn't cure the problem. To understand how to best cure the problem, lets review what a pinch flat is.

Pinch flats are caused when something (road bump, rock, root, small furry critter) causes the tire to collapse into the rim as you roll across it, trapping the tube in between the folded over layers of sidewall with enough pressure to crush through it.



In this case, the tube is also acting as a cushion for the tire and rim. While the tube is destroyed, the forces to the tire and rim are both lessened. If the tube wasn't present, both the tire and rim would have sustained more damage. Think of the tube as a "fuse", blowing out before more damage can happen to your wheel's more expensive parts.

The underlying problem isn't the presence or lack of a tube, but a tire that is able to crush back against the rim in the first place. This is a set up problem, and indicates you have the wrong wheel setup for the riding conditions. There are several factors that can lead up to this situation.
- Under inflation.
- Too small of a tire for the riding conditions.
- Too wide of a tire for the rim/oversized.
- Too narrow of a rim for the size tire.
- Excessive kahunas for the available equipment.

Any one of those factors can cause a problem, but they are all inter-linked. Solving the issue usually means addressing at least two factors.
Experience can help, but if you don't know where to start, start by increasing your air pressure to near max for the tire.
- If that cures the problem but makes the ride harsh, your tire was too small, or the rim was too narrow.
- If that cures the problem but doesn't effect the ride much, your pressure was just too low, or your tire was oversized/too wide for the rim.
- If that doesn't cure the problem at all, your tire was dramatically undersized, or you have an excess of kahunas, and will need to upgrade your whole platform to survive Your kahunas.

So I went past the Lbs this afternoon and bought a minion 2.5 dual ply tyre and a Freeride tube (will fill with sealant) I read your replies along the way. I really didn't want to add more weight to the rear but you guys are most likely correct.

The old school casing minion I bought are actually undersized. Maxxis modern 2.3's are actually larger than an old school 2.5". That said it was a piece of cake to mount and looks like a skinny motoX tyre. Only a smidgen bit larger than my ardent 2.2

Interesting dual chamber setups definitely a better way to go.


Thanks for the tips, will run around 50psi and report back this weekend how harsh it is and if this setup survives


Mike

FWIW, I'm always running too fat a rear tire for my rim, so that may be why I needed even higher pressure to stop the pinch flats. And bear in mind, with those thorns in my tubes, as many as 100 at times broken off in there, I need to keep the tire tall or the thorns shred the top of the tube. At least 40 psi, or I stop to pump. I toss tubes every six months, but the first ride still picks up enough thorns to shred a tube that is not hard and tall.

so for me, it's pump it up.

DS: Wheel is an Alex supra BH downhill rim built with d butted 12g sapim e bike spokes with washers both ends. Rim is approx 34mm internal from memory. Just fitted the minion and it doesn't look oversized for the rim at all. I used to ride the same trails unassisted over and over with 40psi in the rear Larsen 2.0tt with no dramas. I think the thick walled minion with extra psi should do the trick.

Cheers dan, I now know what setup to use if I ride through nails. Keep those thorns over there in the US

Tyre / wheel survived today after being put through 1hr of nasty trails! Chattery running 50psi and hard work manoeuvring the bike now that it weighs double what it used too.I think the same trails are easier to ride unassisted and found myself jumping to far into corners. Still jumped well if not even better with the added stability from the weight even with a 7.5kg hub in the rear. More suited now to open stuff. Might pick up a maxxis Griffen dh tyre down the track. Minion feels very draggy

Cheers guys

Mike