Squirmy Tyres

[943]

Hi all

Still quite new to this MTB thing. Bought a 2nd hand Trek x-caliber 9 2019 a few weeks ago with stock tubeless rims and tyres. The tyres were a bit worn so I treated myself to some new ones - Minon DHF on the front and Aggressor on the rear.

So, replaced the tyres over the weekend and went for a ride this afternoon - part road, part gravel single track.

I’ve now got very unsettling squirm in both tyres - rear being worse than the front. Going around a gentle corner feels like i’m doing a 2-wheel drift.

Is this just a symptom of new tyres or have I done something wrong?

This is my first time with tubeless and I’m an MTB noob so quite possibly I’ve screwed something up.

Pressures are around 35 psi (I’ll need to double check tho).

Thanks in advance.

 

[moorey]

What size tyres and what width rims?

Bigger knobs will squirm more for a start.

 

[943]

Best I can make out is the rims are 29mm. No size marked on the rims - just “Bontrager Kovee TLR”.

Old tyres were 2.2” and new 2.3”. Wouldn’t have thought an extra 0.1” would make any noticeable difference.

 

[Kerplunk]

If your using a road track pump they don’t read very accurately at lower psi. My specialized pump was showing 30psi and when I put a topeak digital guage it read 15psi.. Tyre squirmed like crap as well..

 

[T-Rex]

Glad to see you got a MTB at last!

Two things to check:

1. Verify the accuracy of your tyre pressure guage. Under inflated tyres are squirmy.

2. Technique. You need to weight the front tyre of a MTB to get it to bite, much more so than a road bike. The harder you lean on it the more it grips. If you are leaning back with your arms straight it’s going to drift over the surface rather than grip it.

 

[Chriso_29er]

Sorry never ridden your specific tyres but do have similar Maxxis HR's.

I was riding more XC small block off road tyres and then went to test ride a new bike with the chunky HR's on it. Tyres had just been setup by the shop at about 35psi to help seat them properly. First corner in the carpark I almost binned it, couldn't believe how much the tyres squirmed around.

I would let a little pressure out and take some time to get used to it. Be careful on hard surfaces. They will come into their own in true off-road conditions.

 

[943]

If your using a road track pump they don’t read very accurately at lower psi. My specialized pump was showing 30psi and when I put a topeak digital guage it read 15psi.. Tyre squirmed like crap as well..

Yeah, thought about that. I’ve got a Topeak floor pump I use for my 110 psi road tyres and noted that at the lower pressures, gauge seemed to be a bit arbitrary. Tyres are quite firm though - not heaps of deflection when the bike is mounted.

Might be worth trying a better pump / gauge though to check.

 

[943]

Sorry never ridden your specific tyres but do have similar Maxxis HR's.

I was riding more XC small block off road tyres and then went to test ride a new bike with the chunky HR's on it. Tyres had just been setup by the shop at about 35psi to help seat them properly. First corner in the carpark I almost binned it, couldn't believe how much the tyres squirmed around.

I would let a little pressure out and take some time to get used to it. Be careful on hard surfaces. They will come into their own in true off-road conditions.

Difference between the nobs on the old vs new is quite remarkable. Old tyres are like slicks in comparison. But still, huge amount of lateral movement I wouldn’t have thought would be down to the nob size.

Particularly in dirt when the track surface would move more under the tyre than the tyre itself???

 

[Mattyp]

So, replaced the tyres over the weekend and went for a ride this afternoon - part road, part gravel single track.

I’ve now got very unsettling squirm in both tyres - rear being worse than the front. Going around a gentle corner feels like i’m doing a 2-wheel drift.

Is this just a symptom of new tyres or have I done something wrong?

Thanks in advance.

The only thing i would say is you have put a DH orientated tyre, and you are riding on road/gravel track. Aggressor is not quiet a DH tyre but still designed to be "aggressive". Something like a Maxxis Ardent or Ikon might be better suited,

 

[T-Rex]

943, I’m in Canberra this week if you want to meet up at Stromlo I’m happy to check out your setup and go for a ride with you. Shoot me a PM of you are interested

 

[943]

943, I’m in Canberra this week if you want to meet up at Stromlo I’m happy to check out your setup and go for a ride with you. Shoot me a PM of you are interested

Thanks mate. I’ll see what the kids are up to and hope to make it out there next weekend.

 

[Scotty T]

Thread below for Canberra rides

https://www.rotorburn.com/forums/index.php?threads/regular-rides.314382/

 

[T-Rex]

Thanks mate. I’ll see what the kids are up to and hope to make it out there next weekend.

I’m heading back to Sydney Thursday or Friday might need to be an after work meetup now that daylight saving has kicked in. Unless you have any time off for school hols?

 

[RichJS]

Best I can make out is the rims are 29mm

Trek website says 2019 x-cal 9 say 23mm rims, so you're presumably measuring the outside.

Minions have very large knobs. Consider some more-XC-oriented tyres for the XC bike? Ikon / Ardent / etc?

You're probably just getting used to MTB tyres. I'd be running 10 PSI lower in the rear, even lower again in the front. More squirm but also more grip .. Riding an MTB (particularly hardtail) on tarmac I can notice it, but on dirt the tyres just feel like they're working as expected.