Mondraker Summum

PB Forum :: Downhill
Mondraker Summum
Author Message
O+
Posted: Dec 27, 2018 at 0:11 Quote
jonty4 wrote:
With you on this one like, tried it longer and it just wasn't as snappy for our tight UK trails haha

It was horribly unresponsive for me with the stock head angle
The -2 headset made it "snappy" the -1 feels right to me.
Adding some length back in in the back makes it so you dont have to protect the rear as much.

What springs you fellas using,
At 190 i found a 375 gave 30% sag with 1mm preload but, it just feels way too soft.

Posted: Dec 28, 2018 at 12:30 Quote
englertracing wrote:
jonty4 wrote:
With you on this one like, tried it longer and it just wasn't as snappy for our tight UK trails haha

It was horribly unresponsive for me with the stock head angle
The -2 headset made it "snappy" the -1 feels right to me.
Adding some length back in in the back makes it so you dont have to protect the rear as much.

What springs you fellas using,
At 190 i found a 375 gave 30% sag with 1mm preload but, it just feels way too soft.

I'm 155lb and use a 400x2.8 on the aluminium frame.

My ideal spring weight is 396lb so if you're 190 then 375 us gonna be waaaaay soft.
If you're on a carbon frame you should have a ~500lb spring

O+
Posted: Dec 28, 2018 at 13:04 Quote
oldmanDan wrote:
englertracing wrote:
jonty4 wrote:
With you on this one like, tried it longer and it just wasn't as snappy for our tight UK trails haha

It was horribly unresponsive for me with the stock head angle
The -2 headset made it "snappy" the -1 feels right to me.
Adding some length back in in the back makes it so you dont have to protect the rear as much.

What springs you fellas using,
At 190 i found a 375 gave 30% sag with 1mm preload but, it just feels way too soft.

I'm 155lb and use a 400x2.8 on the aluminium frame.

My ideal spring weight is 396lb so if you're 190 then 375 us gonna be waaaaay soft.
If you're on a carbon frame you should have a ~500lb spring

Interesting,
the leverage ratio is 2.93,
I weighed myself and the bike, 125lbs on rear wheel
2.93x125=366 required spring rate for 1" shock sag
but was really shooting for 0.900" sag, well, the 375 got me to exactly the sag I was shooting for with 1 turn preload.......
was expecting it to be right as rain.
however in riding it this way it feels wrong.

I had the 550, and I currently have a 475, the 550 was horrible, the 475 is bad, the 375 is too soft for sure.
what sag are you getting with your current setup, how much preload?

with the 475 and no preload I was only getting low 20% sag

Posted: Dec 30, 2018 at 7:53 Quote
englertracing wrote:
oldmanDan wrote:
englertracing wrote:


It was horribly unresponsive for me with the stock head angle
The -2 headset made it "snappy" the -1 feels right to me.
Adding some length back in in the back makes it so you dont have to protect the rear as much.

What springs you fellas using,
At 190 i found a 375 gave 30% sag with 1mm preload but, it just feels way too soft.

I'm 155lb and use a 400x2.8 on the aluminium frame.

My ideal spring weight is 396lb so if you're 190 then 375 us gonna be waaaaay soft.
If you're on a carbon frame you should have a ~500lb spring

Interesting,
the leverage ratio is 2.93,
I weighed myself and the bike, 125lbs on rear wheel
2.93x125=366 required spring rate for 1" shock sag
but was really shooting for 0.900" sag, well, the 375 got me to exactly the sag I was shooting for with 1 turn preload.......
was expecting it to be right as rain.
however in riding it this way it feels wrong.

I had the 550, and I currently have a 475, the 550 was horrible, the 475 is bad, the 375 is too soft for sure.
what sag are you getting with your current setup, how much preload?

with the 475 and no preload I was only getting low 20% sag

These are the recommended spring rates from mondraker.
They are different to what most calculators give you due to the progressive stroke on the rear.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.mondraker.com/uploads/images/bike/docs/summum-carbon-pro-20180213114554-setup.pdf&ved=2ahUKEwiI0v7I88ffAhUlzIUKHc3wC64QFjAAegQIBBAB&usg=AOvVaw1UiCcAoxPuh3lAJ8wBt6DC
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.mondraker.com/uploads/images/bike/docs/summum-20180213114531-setup.pdf&ved=2ahUKEwiI0v7I88ffAhUlzIUKHc3wC64QFjABegQIBxAB&usg=AOvVaw06Btm0dOvc6Oh1HHwFzT8U

O+
Posted: Dec 31, 2018 at 16:23 Quote
Ive seen it, notice how its in 50lb increments...



I know how to select a spring, i can calculate it manually, but i made a spring calculator in excell, i have been working with suspension for over 20 years, motocross forks and shocks to super moto, off road buggy and truck shocks to dirt stock cars. I can service and revalve anything ive had custom springs made before from cannnon racecraft, can calculate a springs rate roughly from only dimensions. I can also calculte cut and re close and grind a spring to increase rate for vintage motorcycle applications.

So again, 375 was calculated correctly by me to provide 33% sag with 1 turn preload, was damn near perfect, shock eye to eye was measured with a pair of 12" calipers to measure sag which came in at 0.980" or 35%

Then you ride it and it is a bit soft

What are you measureing for sag?

Posted: Jan 2, 2019 at 4:03 Quote
englertracing wrote:
Ive seen it, notice how its in 50lb increments...



I know how to select a spring, i can calculate it manually, but i made a spring calculator in excell, i have been working with suspension for over 20 years, motocross forks and shocks to super moto, off road buggy and truck shocks to dirt stock cars. I can service and revalve anything ive had custom springs made before from cannnon racecraft, can calculate a springs rate roughly from only dimensions. I can also calculte cut and re close and grind a spring to increase rate for vintage motorcycle applications.

So again, 375 was calculated correctly by me to provide 33% sag with 1 turn preload, was damn near perfect, shock eye to eye was measured with a pair of 12" calipers to measure sag which came in at 0.980" or 35%

Then you ride it and it is a bit soft

What are you measureing for sag?

If you're 28 (as your profile says) then I find the above comment hard to believe....

Your calculation is wrong. The leverage ratio as you quoted before actually has a rising rate. You didn't account for that....
I'm pretty sure anyone who understands even the basics of suspension kinematics would realise that, especially someone with such an accurate eye as yourself...
And my Sag sits at 32% on a 400lb. And I'm lighter than you.
Work that out.....

Posted: Jan 2, 2019 at 6:43 Quote
oldmanDan wrote:
englertracing wrote:
Ive seen it, notice how its in 50lb increments...



I know how to select a spring, i can calculate it manually, but i made a spring calculator in excell, i have been working with suspension for over 20 years, motocross forks and shocks to super moto, off road buggy and truck shocks to dirt stock cars. I can service and revalve anything ive had custom springs made before from cannnon racecraft, can calculate a springs rate roughly from only dimensions. I can also calculte cut and re close and grind a spring to increase rate for vintage motorcycle applications.

So again, 375 was calculated correctly by me to provide 33% sag with 1 turn preload, was damn near perfect, shock eye to eye was measured with a pair of 12" calipers to measure sag which came in at 0.980" or 35%

Then you ride it and it is a bit soft

What are you measureing for sag?

If you're 28 (as your profile says) then I find the above comment hard to believe....

Your calculation is wrong. The leverage ratio as you quoted before actually has a rising rate. You didn't account for that....
I'm pretty sure anyone who understands even the basics of suspension kinematics would realise that, especially someone with such an accurate eye as yourself...
And my Sag sits at 32% on a 400lb. And I'm lighter than you.
Work that out.....

Seems like a troll to me mate

O+
Posted: Jan 2, 2019 at 9:59 Quote
oldmanDan wrote:
englertracing wrote:
Ive seen it, notice how its in 50lb increments...



I know how to select a spring, i can calculate it manually, but i made a spring calculator in excell, i have been working with suspension for over 20 years, motocross forks and shocks to super moto, off road buggy and truck shocks to dirt stock cars. I can service and revalve anything ive had custom springs made before from cannnon racecraft, can calculate a springs rate roughly from only dimensions. I can also calculte cut and re close and grind a spring to increase rate for vintage motorcycle applications.

So again, 375 was calculated correctly by me to provide 33% sag with 1 turn preload, was damn near perfect, shock eye to eye was measured with a pair of 12" calipers to measure sag which came in at 0.980" or 35%

Then you ride it and it is a bit soft

What are you measureing for sag?

If you're 28 (as your profile says) then I find the above comment hard to believe....

Your calculation is wrong. The leverage ratio as you quoted before actually has a rising rate. You didn't account for that....
I'm pretty sure anyone who understands even the basics of suspension kinematics would realise that, especially someone with such an accurate eye as yourself...
And my Sag sits at 32% on a 400lb. And I'm lighter than you.
Work that out.....

Started turning clickers as a little kid racing a cr80.... Wink
Took my first forks apart at 15, start the timer when ever you prefer.
My grandpa assembled sattelites and my dad designs and builds rock crushers and concrete plants, so i was encouraged from a young age to work on my own stuff



http://linkagedesign.blogspot.com/2014/12/mondraker-summum-cf-2015.html?m=1
Sure looks to me like the leverage ratio chart shows 3 at 70mm sag....which is what i used in my spreadsheet.
I also weighed the bike front and rear with me on it in "attack mode" or the position in which i would ride approaching a jump. 100lbs front 125lbs rear
45.35kg front, 56.69kg rear


Perhaps your measuring sag quite over the rear wheel while im measuring in a neutral position?
The 375 did deliver 24mm sag at the shock witb 1mm preload,
Im not trying to argue, simply trying to understand whats wrong. There must be something I am missing. Im open to hear anything you have to say, you seem sharp.

O+
Posted: Jan 2, 2019 at 10:19 Quote
jonty4 wrote:

Seems like a troll to me mate

Absolutely not, I was just wondering if people around here just slap on whatever mondraker or johnny o a the bike shop guesses is good and takes their word for it and run it without measuring sag.

A lot of the locals here are that way.
LOCAL- "such and such at bobbys bikes set my clickers and air pressure for me (even though he has never seen how or where i ride and also doesn't even ride this brand of bike) I don't remember what its set at though and I also guess at my tire pressures"

further more, I wanted to know if anyone who does pay attention found mondrakers choice to use a 550lb spring horrible or if people just ride it like that and think its bitchn. Just turn the compression all the way out and let her rip right???? ummm no thanks.

I really wanted to know if other people that do measure their sag landed directly on mondrakers suggestions or found them to be off.

Thanks,
Aaron Englert.

Posted: Jan 2, 2019 at 10:47 Quote
englertracing wrote:
jonty4 wrote:

Seems like a troll to me mate

Absolutely not, I was just wondering if people around here just slap on whatever mondraker or johnny o a the bike shop guesses is good and takes their word for it and run it without measuring sag.

A lot of the locals here are that way.
LOCAL- "such and such at bobbys bikes set my clickers and air pressure for me (even though he has never seen how or where i ride and also doesn't even ride this brand of bike) I don't remember what its set at though and I also guess at my tire pressures"

further more, I wanted to know if anyone who does pay attention found mondrakers choice to use a 550lb spring horrible or if people just ride it like that and think its bitchn. Just turn the compression all the way out and let her rip right???? ummm no thanks.

I really wanted to know if other people that do measure their sag landed directly on mondrakers suggestions or found them to be off.

Thanks,
Aaron Englert.

Weighing yourself on the bike while it is level won't give you the correct bias of weight between the wheels, as we rarely are on level ground while riding dh.
Plus, rider weight is massively dynamic and the weight applied to each wheel changes dramatically while riding.

When I first Rode my summum, it felt too soft with the stock 400lb spring. But the Sag was just below 23mm (32%).
After riding it, I came to the conclusion that the frame has a huge ramp up at the end of the stroke. When you have a rising rate like that, usually the designer (if they are any good) allows the beginning stroke to be more supple, with a gentle rising rate until the ratio steepens.
This gives more Sag, and thus more grip and small bump sensitivity.
So this is where the lsc comes into play.
If you know what spring you want/need, and it doesn't feel right (but the numbers say it is) then you need to start tuning your damper to make it feel right for you. Some like it firm and slow, some like it lively and fast. Both can be achieved with the same spring, and a little bit of knowledge.

The lsc on the summum is very important, the hsc is less important due to the natural progressive stroke.
Without lots of low speed compression, the bike feels wallowy and too soft because of the leverage ratio at the beginning stroke. The bike feels too soft because the frame is pitching under your movements.
Controlling this is the key to the summum.

My lsc is one click away from full on, my hsc is about 2 clicks in.

It solved the 'too soft' feeling immediately for me, and it's made it probably the fastest bike I've ever ridden.

O+
Posted: Jan 2, 2019 at 11:05 Quote
oldmanDan wrote:
englertracing wrote:
jonty4 wrote:

Seems like a troll to me mate

Absolutely not, I was just wondering if people around here just slap on whatever mondraker or johnny o a the bike shop guesses is good and takes their word for it and run it without measuring sag.

A lot of the locals here are that way.
LOCAL- "such and such at bobbys bikes set my clickers and air pressure for me (even though he has never seen how or where i ride and also doesn't even ride this brand of bike) I don't remember what its set at though and I also guess at my tire pressures"

further more, I wanted to know if anyone who does pay attention found mondrakers choice to use a 550lb spring horrible or if people just ride it like that and think its bitchn. Just turn the compression all the way out and let her rip right???? ummm no thanks.

I really wanted to know if other people that do measure their sag landed directly on mondrakers suggestions or found them to be off.

Thanks,
Aaron Englert.

Weighing yourself on the bike while it is level won't give you the correct bias of weight between the wheels, as we rarely are on level ground while riding dh.
Plus, rider weight is massively dynamic and the weight applied to each wheel changes dramatically while riding.

When I first Rode my summum, it felt too soft with the stock 400lb spring. But the Sag was just below 23mm (32%).
After riding it, I came to the conclusion that the frame has a huge ramp up at the end of the stroke. When you have a rising rate like that, usually the designer (if they are any good) allows the beginning stroke to be more supple, with a gentle rising rate until the ratio steepens.
This gives more Sag, and thus more grip and small bump sensitivity.
So this is where the lsc comes into play.
If you know what spring you want/need, and it doesn't feel right (but the numbers say it is) then you need to start tuning your damper to make it feel right for you. Some like it firm and slow, some like it lively and fast. Both can be achieved with the same spring, and a little bit of knowledge.

The lsc on the summum is very important, the hsc is less important due to the natural progressive stroke.
Without lots of low speed compression, the bike feels wallowy and too soft because of the leverage ratio at the beginning stroke. The bike feels too soft because the frame is pitching under your movements.
Controlling this is the key to the summum.

My lsc is one click away from full on, my hsc is about 2 clicks in.

It solved the 'too soft' feeling immediately for me, and it's made it probably the fastest bike I've ever ridden.

Interesting take
Are you running the dhx2?


I bought a 400, and im trading my 475 which also felt really bad for a 425, so hopefully ill be able to find what i like without owning the entire catalog of springs. though obtaining a 450 may still be necessary.

Posted: Jan 3, 2019 at 14:43 Quote
englertracing wrote:
oldmanDan wrote:
englertracing wrote:


Absolutely not, I was just wondering if people around here just slap on whatever mondraker or johnny o a the bike shop guesses is good and takes their word for it and run it without measuring sag.

A lot of the locals here are that way.
LOCAL- "such and such at bobbys bikes set my clickers and air pressure for me (even though he has never seen how or where i ride and also doesn't even ride this brand of bike) I don't remember what its set at though and I also guess at my tire pressures"

further more, I wanted to know if anyone who does pay attention found mondrakers choice to use a 550lb spring horrible or if people just ride it like that and think its bitchn. Just turn the compression all the way out and let her rip right???? ummm no thanks.

I really wanted to know if other people that do measure their sag landed directly on mondrakers suggestions or found them to be off.

Thanks,
Aaron Englert.

Weighing yourself on the bike while it is level won't give you the correct bias of weight between the wheels, as we rarely are on level ground while riding dh.
Plus, rider weight is massively dynamic and the weight applied to each wheel changes dramatically while riding.

When I first Rode my summum, it felt too soft with the stock 400lb spring. But the Sag was just below 23mm (32%).
After riding it, I came to the conclusion that the frame has a huge ramp up at the end of the stroke. When you have a rising rate like that, usually the designer (if they are any good) allows the beginning stroke to be more supple, with a gentle rising rate until the ratio steepens.
This gives more Sag, and thus more grip and small bump sensitivity.
So this is where the lsc comes into play.
If you know what spring you want/need, and it doesn't feel right (but the numbers say it is) then you need to start tuning your damper to make it feel right for you. Some like it firm and slow, some like it lively and fast. Both can be achieved with the same spring, and a little bit of knowledge.

The lsc on the summum is very important, the hsc is less important due to the natural progressive stroke.
Without lots of low speed compression, the bike feels wallowy and too soft because of the leverage ratio at the beginning stroke. The bike feels too soft because the frame is pitching under your movements.
Controlling this is the key to the summum.

My lsc is one click away from full on, my hsc is about 2 clicks in.

It solved the 'too soft' feeling immediately for me, and it's made it probably the fastest bike I've ever ridden.

Interesting take
Are you running the dhx2?


I bought a 400, and im trading my 475 which also felt really bad for a 425, so hopefully ill be able to find what i like without owning the entire catalog of springs. though obtaining a 450 may still be necessary.

on my old summum alloy i ran a 450 sls spring in a dhx rc4 kashima and im 182 lbs and i found it really good pretty sure oldmandan gave me a base set up for it and i changed it slightly

Posted: Feb 27, 2019 at 8:23 Quote
29er wheels on summum carbon?
With adjustable chainstay rear wheel will fit with no problems... Fox 49 or boxxer 29 to fit front wheel...
But bb will be a little raised up.
Any ideas to lower it? Fit a 216x63 shock?

O+
Posted: Feb 27, 2019 at 10:30 Quote
Have a spacer put inside the shock,
I bet you can get someone like steve at vorsprung to do something like that.
The 29" will raise it 3/4" or 19mm.
The leverage ratio at 19mm is 3.3-1
So youll need to reduce the shocks length by 5.75mm,
Personally i think the bb is way low and id run 4.5 to 5mm.
Or hit the easy button and grab that 216x63
Smile

Posted: Mar 1, 2019 at 3:10 Quote
englertracing wrote:
Have a spacer put inside the shock,
I bet you can get someone like steve at vorsprung to do something like that.
The 29" will raise it 3/4" or 19mm.
The leverage ratio at 19mm is 3.3-1
So youll need to reduce the shocks length by 5.75mm,
Personally i think the bb is way low and id run 4.5 to 5mm.
Or hit the easy button and grab that 216x63
Smile
Thanks!
I just need a new fork and a 29er wheelset now! maybe too much for an experiment..... Big Grin Eek


 
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