2019 Stumpjumper Evo

PB Forum :: Specialized
2019 Stumpjumper Evo
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Posted: Nov 8, 2019 at 4:08 Quote
vasilly wrote:
After a month on alloy S3 29" I would say - go for 29"! I've been on a 27,5" for 4 years prior and after a first day I was impressed by the way the 29" smooths the trails. No lost for joy of jumping at all. Grip in cornering better also.

What's your height?

Posted: Nov 8, 2019 at 8:02 Quote
I'm just over 5'8 and on a S3... go long!

Posted: Nov 8, 2019 at 14:18 Quote
Hello! Do you think that beast is going to be fine for someone who is 165cm/5’5”?
I want to buy a new bike for my wife. She’s somewhere near intermediate rider. Nicolai, for example, states Saturn 14 with reach 450 for riders with height below 170. Unfortunately we can’t ride before buy. one of mine concerns is riding to/from local trails. It’s about 40km total on almost flat asphalt road. How much exhausting it could be on such a long bike?

She rides Norco XC hard tail with 27.5 wheels on local trails and rents specialized dh bike with 26 wheels in bikepark.

Posted: Nov 8, 2019 at 14:59 Quote
S3 is definitely too much for a rider of her size. S2 should work.

The long bike will not add to the fatigue in any way. Precisely zero. Rolling resistance of the tires, aerodynamics, and suspension stability during pedaling are all concerns, but not length. At all.

Another concern is whether an intermediate rider will enjoy such a stable bike. The geometry is pretty much a short-travel DH bike. If you're looking for one bike to replace both the hardtail and the rented DH bikes, then I suppose this is one of the best compromises available, but it could be the worst of both worlds if it's far too much bike for the local trails and less fun than a true DH bike at the bike parks.

Posted: Nov 9, 2019 at 13:18 Quote
jaydawg69 wrote:
I'm just over 5'8 and on a S3... go long!
Are you on 27.5 or 29?

Posted: Nov 9, 2019 at 22:45 Quote
severniy wrote:
jaydawg69 wrote:
I'm just over 5'8 and on a S3... go long!
Are you on 27.5 or 29?

29

Posted: Nov 10, 2019 at 0:44 Quote
I made the mistake of riding a pivot firebird today. It handles the square edged hits so much better than the Evo. This is the only downside of the Evo to me. If anyone has a solution to this rear end let me know. I am trialling out an EXT Storia while I’m in New Zealand so hopefully that’s the solution.

Posted: Nov 10, 2019 at 1:28 Quote
Axle path maybe?


Interestingly, my Evo handles square edge hits and overall chunk in a much calmer way relative to my former Bird AM9, to the point I use flat pedals anywhere 100% of the time on the Evo (I'd alternate depending on the track with the AM9.
In this case I blame it on the very high AM9 anti squat.

Mind I have the Evo shock spacer removed

Posted: Nov 10, 2019 at 2:42 Quote
Arierep wrote:
Axle path maybe?


Interestingly, my Evo handles square edge hits and overall chunk in a much calmer way relative to my former Bird AM9, to the point I use flat pedals anywhere 100% of the time on the Evo (I'd alternate depending on the track with the AM9.
In this case I blame it on the very high AM9 anti squat.

Mind I have the Evo shock spacer removed

It could be. I have my hsr rebound closed (vorsprung method) and tune via the Lsr circuit and still have issues maintaining feet to stay on the pedals on square edge hits. Spring rate is spot on, I wouldn’t want to go any lower there as bottoming resistance is poor with the minimal progression.

I absolutely love this bike, however the rear suspension leaves me wondering something. I do love a DW link rear end.

Posted: Nov 10, 2019 at 9:34 Quote
Brasher wrote:
I made the mistake of riding a pivot firebird today. It handles the square edged hits so much better than the Evo. This is the only downside of the Evo to me. If anyone has a solution to this rear end let me know. I am trialling out an EXT Storia while I’m in New Zealand so hopefully that’s the solution.

The EXT Storia will be the solution. IMO the best shock for this bike.

Posted: Nov 10, 2019 at 12:52 Quote
bedwards13 wrote:
Brasher wrote:
I made the mistake of riding a pivot firebird today. It handles the square edged hits so much better than the Evo. This is the only downside of the Evo to me. If anyone has a solution to this rear end let me know. I am trialling out an EXT Storia while I’m in New Zealand so hopefully that’s the solution.

The EXT Storia will be the solution. IMO the best shock for this bike.

Yep, a very expensive solution Smile

Posted: Nov 10, 2019 at 16:32 Quote
Brasher wrote:
bedwards13 wrote:
Brasher wrote:
I made the mistake of riding a pivot firebird today. It handles the square edged hits so much better than the Evo. This is the only downside of the Evo to me. If anyone has a solution to this rear end let me know. I am trialling out an EXT Storia while I’m in New Zealand so hopefully that’s the solution.

The EXT Storia will be the solution. IMO the best shock for this bike.

Yep, a very expensive solution Smile

You are worth it Wink

Posted: Nov 10, 2019 at 23:15 Quote
Arierep wrote:
In this case I blame it on the very high AM9 anti squat.

I'm not doubting your experience of the two bikes having different bump compliance, but I think you've incorrectly attributed it.

For a given sprocket combination, bikes with high anti-squat have a high virtual pivot point ("instant centre"). There's a little more to it than that, but that's the general idea. It's widely believed a high instant centre improves compliance: this is one of the reasons for the recent appearance of some high pivot designs with idler sprockets to manage kickback. Therefore, high anti-squat usually results in better impact management, all else being equal.

The ways in which high anti-squat can harm compliance:

1. Pedal kickback interfering with suspension function.
2. Derailleur clutch force interfering with suspension.

Pedal kickback while coasting is a myth and this can be calculated:

• Take the circumference of the wheel.
• Calculate the maximum pedal kickback in any given sprocket combination, in degrees.
• Multiply (kickback / 360°) × circumference. This is how much the wheel would have to rotate to negate all kickback.

• Take the speed you usually travel while using the sprocket combination from the previous calculation.
• Calculate how long it would take you to travel the distance from the previous calculation. This is the maximum allowable time in which to fully - from top-out to bottom-out - compress your shock for any pedal kickback to occur, let alone enough kickback to be a problem.

• Divide you shock's stroke by this time you just calculated. That's the shaft velocity of the slowest possible impact that will produce any kickback. You will find this shaft velocity is unrealistic. If your shock goes from top-out to bottom-out in 0.03 seconds, for example, you have bigger problems than a little kickback.

But wait, there's more!

This calculation didn't even account for any delay in the engagement of your hub's driver. If the average engagement is, say, 10°, then the average amount of engagement is 5°. This takes 5°×(rear/front sprocket) off the average possible amount of kickback in a full travel impact, making the situation even less likely to produce any kickback, let alone problematic kickback.

Similarly, it's essentially a myth that the derailleur clutch can interfere with suspension. I'll be more brief this time:

1. The clutch doesn't move immediately and often doesn't move at all.
2. If the clutch does move, the clutch breakaway occurs after the suspension starts to move, so it doesn't contribute to "breakaway" force.
3. If the clutch does move, the static friction does hamper suspension performance, but the force is so small, relative to everything else happening in an impact event.
4. Once the clutch is in motion, the dynamic friction and spring force simply add to the spring and damper forces of the suspension.
5. The motion of the clutch is so small. Work = force × distance. The force is small: you can easily move it with one finger; think of how small that is, compared to the impact. The distance is small: the clutch rotates only a few degrees. Thus, the work to overcome is it virtually nothing.

So, why did Gwin and Mulally have great results without chains? It certainly wasn't because of the "improved" suspension performance from not having kickback and/or clutch interference. My guess is they knew they had to be super smooth, since they couldn't recover from a mistake with some pedaling, so they rode with fewer errors and perfectly executed the "slow in, fast out" philosophy of corners.



P. S. Regarding the discussion of EXT shocks in this thread: I ride an EXT Arma. It's really nice. Difficult to say whether it's worth the price, but it really is nice. Did I mention it's nice?


 
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