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This weekend we went and got the wife her first mountain bike, she went for a Trek Roscoe, the spec is bloody good for the money IMHO and most importantly of all she likes how it looks, so will ride it.
Now it comes with Bontrager tubeless ready 27.5" wheels and tubeless ready Maxxis Minnions front & rear, AFAIK they're the 3" wide ones.
I run tubeless on my bikes, but they're XC 29ers so I'm fine with sealant quants and pressures for me. On these plus tyres I haven't got a clue, so any pointers would be handy.
I'm thinking about 150ml sealant in each? The bike will be used for riding with the kids on tame forest trails and maybe a green or blue eventually if I take them all to Llandegla.
If I was riding it, I'd imagine about 15psi front and 17psi rear (I'm 76kg) so as the wife is a bit heavier, I thought say 18psi front and 20psi rear? Without saying the weight difference, how heavy are you and what pressures would you ride in those tyres?
I'm 76kg, 3" tyres on a rigid bike. Run 14psi back and 12 psi in the front. Your pressures sound high to me.
Trial and error with the pressure and it depends if she's smashing berms, where low pressure will feel scary, or just pootling about.
Just put a bit more sealant in than you usually would, don't go mad.
In the right ballparks I’d say.
I’d be expecting to start around 19-20psi and work down from there at 3”, using the time honoured approach of starting with excessive pressure and slowly reducing on a ride until I decide I have it right, then noting whatever pressure that was.
I seem to recall using 150ml at 2.8”.
I ride 29x3 at 15psi. I ride hard and fast with 2foot drops. 20psi was far too hard on 29x3.
Make sure you can prescisely measure the pressure, 1 or 2 psi makes a big difference. A track pump with 160psi guage is barely reading at 15psi.
29+ Minion DHF and Chronicle here.
I just put about twice the sealant that I would in a 2.3 27.5 tyre. Seems to work.
I way 85kg in the buff, so over 90kg kitted up, and run 12psi F and 13psi rear. Any more and feels too bouncy.
27.5” x 3” here. I’m 120kg, so a big outlier, I run 18psi rear, 16psi front. But that’s on all surfaces and different trails.
I’d wouldnt go too low though for tame forest paths and pootling, slight above where you would want to be for trail riding will make it feel sprightly and fast rolling. Then lower them a bit for Llandegla, etc.
Second the advice for a decent pressure gauge, I’ve got the Fabric Accubar gauge that you can use inline with any track pump or compressor.
Digital pressure gauges are in iffy territory at these sort of pressures but generally still usable. Consistency is key, pick a gauge and stick to it if you want the numbers to mean anything.
Full Fat pressures (below 10psi) and you really start seeing how accurate electronics aren’t. Actual analogue dial gauges are the only way if you want true low pressure accuracy.
Track pump gauges do go rapidly off-spec below 30psi or so. By the time you’re sub-20 they’re probably useless.
Sidewall construction makes a huge difference to how plus tyres behave. As a general rule, tyres where the weight is in a tougher sidewall will go fast at lower pressures better. When plus was a new thing, the manufacturers basically decided they’d never sell heavy tyres after years of telling people how great light tyres and wheels were, so essentially sabotaged the entire idea by designing crap tyres that weren’t too much heavier than regular...
^ can you recommend a good gauge? been using a topeak digital one but theres a LOT of air between each whole number as theres no fractional value.
On my plus wheelset I have DHF and DHR combo (EXO) both 2.8s.(38mm internal rims) I'm just over the 80kg mark and run approx 17 psi all round.
(on my 29er wheelset i have a 2.5 DHF and a 2.4 ardent, also EXO at low 20s PSI (not dialled yet) on 27 internal rims)
going tubeless made a big gain with the plus wheels, less so with the 29. all done using orange seal.
I use an analogue accu-gage bought on ebay which is low pressure and seems consistent. I run 9psi front on a 3" tyre and 11psi on a rear 2.8" tyre. I'm only 56kg though.
I've been using the OKO off road vehicle sealant, 100ml of that plus 50ml added water. I've no idea if I've had any punctures to seal
The Topeak is what I’m using too. It’s not terribly accurate compared to the dial gauges you find marketed at Fat riders and can suffer from taking on sealant (can minimise this by measuring with valve at/near wheel TDC but due to fluid this will only stop runoff, no way to stop blown droplets) and it’s not apparently easy to service when this eventually kills the unit, but it’s a good consistent reading so useful tool. It’s been fine for me on plus and tbh it was fine for me on Full Fat too, but I accept it’s not got the resolution for truly low pressure if you want more accurate than 5psi +/- 0.9. I actually view this as a plus, as adding significant digits would give an impression of low pressure accuracy that’s unwarranted. Any electronic device ever has fudge factors built in simply because component tolerances exist, and without fudging them you’d never get anything built...