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 A somewhat surprising tire evaluation

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sanluissound




PostSubject: A somewhat surprising tire evaluation   Mon Jun 24, 2013 8:29 pm

Last night I swapped out my rear wheel/tire. I had been rocking the Pirelli MT 43 which was the only thing I've used since the factory Trail Wings.

My wife is short so after about 200 miles on her WR with the factory 18"/21" she was still uncomfortable with the height (lower seat and link installed... she's short) so I put on a set of WRX wheels with knobby tires (she's happy now).

I seem to be melting the tread off my MT 43 quicker than I'd like. Knowing I've got a handful of trips planned this year I wanted to try a different tire and see how it would compare to my DOT Trials rubber.

I threw on the near new wheel and tire we had left over - that rubber is a Dunlop 606 with the afore mentioned 200 or so miles, and headed off this morning to my beloved Switzerland Trail above Boulder, CO. 

I've been riding the Switz Trl every week now for the last month or so - the conditions have changed a little with the addition of more traffic and drier conditions -
- About 8.5 miles one way on the main section - curvy with ascents and descents as it's essentially a shelf road - mild sand/a little mud/pot holes/numerous rock ledges from 4 - 10" and large, loose rocks everywhere. You could ride the whole thing sitting down but you'd get beat up and would have to travel slow. I encountered two mountain bikers and one pedestrian with a dog today so as much as I like to ride it hard I have to be cautious of others. I averaged 22 mph with a top speed of 37 (there's a 1/2 mile of private property in the middle of the ride that I observe as - go as slow and quiet as I can).

Side by side the MT 43 is taller and narrower, the 606 the opposite. The 43 has less sidewall tread and a larger radius knob area. I've been happy with the 43 but have almost nothing to compare it to.

With 28 psi (rear and front which is a MT 21) I started at the southern end and hauled ass out and down over the first section which is very rough, loose rocks and ledges. Right away the bike felt unstable - the rear end going everywhere. After that is a sandy corner in which I almost lost the rear end. I backed off and readjusted my riding position then got back on the throttle - going into a sand berm I lost the front end and went down. Ack! Back up and playing with different techniques in different areas I still felt very unstable in the back end and not as confident as usual in the front.

At the far side I turned around, aired down to 18 psi (each tire) and tried to race back. I felt a bit better and made a slightly better time. I didn't loose it in any of the sand berm turns but still felt the front end drifting more than it ever has.

My forks are presumably as they were set from the factory, my shock I've softened up way too much to accommodate my 30" inseam. I know my suspension needs to be properly set and that I'll do right away. But even with that in mind I can't help but feel that the 43 outperforms the 606 in a big and noticeable way. Tomorrow I'll put the Pirelli back on the rear and properly set my forks and shock.

- Could the 606 reveal the problems in my suspension set up more so then the 43?

- Would a couple of passes at a lower psi on the 606 be worth a try (I want to give it a fair shake)?

- Is the 43 as a front tire now a viable consideration?

 Any thoughts, insights and commentary in general is much appreciated!


Last edited by sanluissound on Wed Jun 26, 2013 2:33 pm; edited 1 time in total
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Jäger
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PostSubject: Re: A somewhat surprising tire evaluation   Mon Jun 24, 2013 9:40 pm

Moved to Tires forum...

As a side thought, DualSportMaps.com is the ideal place for posting up rides, where others can download the .gpx file, view pictures related to the route, associated waypoints for fuel, food, camping, etc.
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millert85




PostSubject: Re: A somewhat surprising tire evaluation   Wed Jun 26, 2013 1:27 am

i personally hate the 606 but thats not the question.

since the 606 is a shorter tyre it will lower the back slightly. this will lengthen the rake/soften steering angle, giving a slightly slower steering response.  BUT... it will also move the centre of gravity rearwards, taking weight off the front suspension and adding to any wash out issues. i believe this would be made worse by the pressure you were running.

Try... (one thing at a time)
1. on dirt/sand with a MT21 F and 606 R i would be thinking 15psi/14psi ish area. check that first.
2. measure amount of fork tube out the top of triple clamp, now push them through another 3-4mm (if you have room too). Do this test with your 28psi and the 14/15psi in the tyres.
3. measure and set rear rider sag (plenty of guides if you google it). once set correctly run the same test in 1 and 2. with forks through, both pressures and with forks lowered both pressures.

Record everything you do on a note pad and run the same section of track each time. Report back on what you find and i might be able to add to that.
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sanluissound




PostSubject: Tire pressure and suspension tweaks on deck   Wed Jun 26, 2013 2:46 pm

millert85,

Thanks for the input!

- I've already got the forks up in the triple just short of 7mm (6.8 per my calipers). I presume I can move them further.

- I've had the MT21 (front) down to 10psi for a lot of riding and really liked it. However, I didn't bring it down that far for my first set of test rides so you're advice will be taken and I'll air down to 14/15

- Without a doubt my sag and damping adjustments need to be worked out - the rear end is soft, very soft.

- I should have mentioned that in the move towards shortening the bike I installed a Yamalink - this was done with the factory tires on. I felt that in addition to lowering the bike the steering quickened a bit.

I'll make my adjustments and report back!
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millert85




PostSubject: Re: A somewhat surprising tire evaluation   Wed Jun 26, 2013 11:37 pm

dont change the clickers until you've run the tests so you have a consistent baseline.
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sanluissound




PostSubject: Re: A somewhat surprising tire evaluation   Thu Jun 27, 2013 1:04 am

Sounds smart. I've just about got the sag set - will note the clickers but leave them alone. Hoping to try and get out to test over the next two days.
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dhally

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PostSubject: Re: A somewhat surprising tire evaluation   Thu Jun 27, 2013 11:05 am

I've used the MT43 and the D606 on both front and rear (the D606's were on other bikes).  I had tried competition trials tires on my old enduro bike front and rear, and loved the traction, so I went with MT43's front and rear on the WRR.

I run 15 to 20 psi for pavement only, normally run 10-12 psi for dual sport, and would run as low as 8-9 psi for dirt on either tire.  I feel that the MT43 has more dirt traction both front and rear than the D606.  The front may not be quite as precise but I'm willing to live with that for the extra traction, especially on slippery rocks and gravel.  

Both tires work well on the pavement at higher pressures, but the MT43 is much smoother and quieter.  The MT43 front tends to roll sideways on the pavement at lower pressures, which feels weird but doesn't cause a problem.  The MT43 is reported to get better life, and that was also a major factor since I hate changing tires.

I do feel that the MT43 below 10psi provides some cushioning for trail junk.  It seems a little softer than the D606 but nowhere near as soft as a real trials tire.  My suspension is stock, and it needs all the hlep it can get.
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mucker

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PostSubject: Re: A somewhat surprising tire evaluation   Thu Jun 27, 2013 6:03 pm

My last set was 606 f/r...my current set is 43 f/r.
I liked the 606 rear...stable at high speeds, some dirty traction when you aired it down. The front never worked well...but was stable at high speeds and felt ok on tarmac.
So far...the 43s work real well on the slower tough stuff...they make me look better in the awkward sections.
At the moment I run 12 psig front/ 8 psig rear.
They work well enough on the tarmac...but at speed...they feel less stable...maybe more pressure would change that.
On the trail...it helps with a lot of obstacles. Slick mud sucks for both sets...
At the mx track or wot roads, I sacrifice a lil...but when it gets tough, for me, the 43s are a help.
Front tires have similar grip...but the 43 just smooths things out better...again, when its tough. The 606 fr just does...can't seem to come up with a compliment better than that.
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sanluissound




PostSubject: MT43's   Fri Jun 28, 2013 11:09 am

dhally/mucker,

Thanks for the input. I still need to do some iterative analysis but I think the writing is on the wall - Trials type tires for most of my needs. The MT43 on the rear is close to being a clear winner for me, I'm going to consider one on the front but am also looking at the MT16. Dialing in tire pressure is a big part of the picture as well as getting the suspension properly set.

It's been in the upper 90's two days straight and yesterday I woke up to the smell of more burning woods here... I need to rally and  get out there to complete my test rides. I'll report back.
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