Leg fatigue and pain when riding downhill fast.

[EMTB Rider]

I always thought that I needed to exercise more to strengthen my legs to remedy this problem. I recently notices that when riding my Specialized Enduro bike downhill that I didn't have the pain, but when riding my Trek Rail and all the other bikes that I have owned within in minutes my right leg was on fire. This is what causes the problem: Bike geometry, Suspension setup, and type of rear suspension. Both of my bikes are setup properly. The Specialized suspension and geometry is better than most bikes out there. The rear suspension moves rearward during its suspension cycle thus making brake bumps and square edge hits feel invisible. This suspension style will take the stress off your legs and give you the strength to ride all day. Geometry and Suspension setup will greatly help with this but good rear suspension is the cure.

Bike Geometry: Bike must fit you properly for the type of riding you do

Suspension Setup: Front and rear suspension must be setup properly. Sag balanced front and rear, High and Low speed Rebound, and Compression.

Rear Suspension: Purchase a bike that the rear suspension moves in a rearward direction during its suspension cycle.

 

[Mteam]

Rear Suspension: Purchase a bike that the rear suspension moves in a rearward direction during its suspension cycle.

dont think its as simple as that.... plus do you know that the rear wheel on the trek does move backwards a little in the early part of the stroke?

see the 4th chart in this review - it doesnt move back by much, but it is rearward.

(7) 2022 Trek Rail 9.9 Review - EMTB Forums

in fact if you compare to this review of the enduro (see chart toward s the bottom of the article)

Specialized's Launches All-New Enduro 29 - The Loam Wolf

The trek rail has about the same rearward movement as the enduro.

 

[Mikerb]

A rearward arc of the rear wheel under compression is nothing new despite Spesh making it sound like one on the V3 Levo. Most bikes set up for Enduro rather than trail type riding will be set up that way. Designers choose a pivot point and shock tune, that delivers the right compromise between pedal efficiency and rear wheel bump compliance in line with the requirements for whatever type of riding the bike is aimed at.

You complained of pain in one leg. First thing you need to think about is whether that is your lead foot or not; then whether the pain comes on when on the saddle or up on the pedals.
If the pain is when you are up on the pedals ( and I assume level pedals) your lead foot takes more of your weight and does more of the pushing with ankle down. The difference between your different bikes is therefore ( in that scenario) the balance of your weight taken on your arms/hands compared to your legs and that is a cockpit fit issue.

 

[dobbyhasfriends]

[prepares popcorn and waits for Gary.....]

 

[KnollyBro]

So many variables, so little time. For everything else, there is MasterCard!

 

[Gary]

That popcorn better be sweet Dobs

Specialized suspension and geometry is better than most bikes out there. The rear suspension moves rearward during its suspension cycle thus making brake bumps and square edge hits feel invisible

Lol
No it doesn't.
Neither of the bikes Mteam mentioned have a rearward axle path.
both bikes axle paths move an absolutely a miniscule amount (around 1mm ish) of rearward movement BEFORE their sag point. ie. not actually in use over rough unforgiving terrain
The rest of the axle path is forwards arcing.
anyone who suggests this is a rearward axle path is holding a well and truely stacked kool-Aid loyalty card

 

[Gary]

do you ride left leg forwards?
A large part of the reason your legs are getting tired descending is from using too much rear brake

 

[dobbyhasfriends]

That popcorn better be sweet Dobs

salty, like you

I had this and still do after a whole day at the bikepark but then I watched Ben Cathro's video on body position in the 'how to bike' series and realised straight away it was my bad body position.
I found I was squatting constantly on the bike and once i got the 'boss stance' sorted I was ok but it was weird at first cos I was higher up and further over the front so I had to change other things about my riding, all of which were good !!

 

[jimbob]

do you ride left leg forwards?
A large part of the reason your legs are getting tired descending is from using too much rear brake

Would you mind explaining a little bit more about why that is?

Genuine question BTW. Struggling to work out how that would affect the legs!

 

[RustyIron]

When I'm done with a ride, my legs hurt, my arms hurt, my shoulders hurt, and if there are any parts leaking red juice, they're gonna hurt, too. Clearly, I need to watch some videos and buy a Specialized.

 

[Gary]

Would you mind explaining a little bit more about why that is?

Genuine question BTW. Struggling to work out how that would affect the legs!

Firstly it alters your body position and puts more load through your legs.
Secondly it reduces the effectiveness of the bike's suspension and reduces rear grip.
Your rearward foot also takes more of the pummelling than your forward foot.
Planning and choosing your braking points and braking when required rather than dragging your brakes not only allows you to ride faster with more grip it allows you to ride with less fatigue.

 

[KnollyBro]

Firstly it alters your body position and puts more load through your legs.
Secondly it reduces the effectiveness of the bike's suspension and reduces rear grip.
Your rearward foot also takes more of the pummelling than your forward foot.
Planning and choosing your braking points and braking when required rather than dragging your brakes not only allows you to ride faster with more grip it allows you to ride with less fatigue.

OP Quote:
"I always thought that I needed to exercise more to strengthen my legs to remedy this problem. I recently notices that when riding my Specialized Enduro bike downhill that I didn't have the pain, but when riding my Trek Rail and all the other bikes that I have owned within in minutes my right leg was on fire."

Although the OP's post is tad anecdotal, your suggestion of dragging the back brake (which is bad), does not explain why the OP notices a difference within minutes. Also, if the majority of load is not goin thru the legs (downhill), then more load would have to go thru your wrists and hands (I choose legs!) My hands always give out long before my legs. My wife is the opposite. Her right leg gives out. She says I use too much rear brake.

 

[Doug Stampfer]

Firstly it alters your body position and puts more load through your legs.
Secondly it reduces the effectiveness of the bike's suspension and reduces rear grip.
Your rearward foot also takes more of the pummelling than your forward foot.
Planning and choosing your braking points and braking when required rather than dragging your brakes not only allows you to ride faster with more grip it allows you to ride with less fatigue.

Good God Man I think you're talking sense there. I am going to put that to the test on the next ride.
The only problem with your solution is that for me, riding faster is not a priority but keeping the speed within my zone of reactionability is.

 

[StuR]

I'm no pro downhiller and i certainly don't fully understand the science of it but I find actively pushing my heels down instantly relives any and all pain in my legs when descending
I keep my feet level as much as possible, apart from loading the outside foot more when cornering
The moment I get lazy and forget to drop my heels my thighs burn like hell , push my heels down and the pain instantly stops
I guess it has something to do with different muscle groups being used.
Try it sat on the sofa and you'll notice different muscles working
As I said, I don't claim to fully understand it , but it works for me instantly everytime

 

[Gary]

does not explain why the OP notices a difference within minutes.

complaining your legs are on fire after just a few munutes descending is pretty clearly because of lack of strength/fitness.
Nonsense typed regarding suspension axle path also tells us what he's feeling is more than likely also partially down to placebo effect. Although suspension performance under braking is far from equal between all rear suspension designs and in this respect some bikes will feel more harsh than others.

I wouldn't waste too much time worrying about the anecdote.
bottom line is strength, fitness and technique will all help more than worrying about axle path between different forward arcing axle path frames.
Optimum suspension set-up, tyre set-up/pressures and the actual rear shock can also make a big difference to the performance of any bike. The information we have before us is far too vague to come up with any definative conclusions as to why the OP has less pain riding the spesh Enduro.

 

[EMTB Rider]

The bike I am referring to is the Specialized Enduro Comp pedal bike " none ebike"
Less Hang-Up, More Speed
If speed is your objective, square-edged bumps are your enemies. They cause your rear wheel to hang up momentarily on impact, which you feel as a sudden backwards yank on the pedals. The impact your suspension should be absorbing is instead transferred to both you and your frame. You wind up more tired and a lot less fast.

Taking inspiration from the new Demo, we moved the Enduro’s main pivot forward and raised the bike’s instant center, which minimizes rear wheel hang-up by giving the bike a more-rearward axle path in key stages of the wheel travel. Impact energy is transferred into the suspension, where it belongs, instead of into you. Voila, you just got faster.

 

[Mteam]

The bike I am referring to is the Specialized Enduro Comp pedal bike " none ebike"
Less Hang-Up, More Speed
If speed is your objective, square-edged bumps are your enemies. They cause your rear wheel to hang up momentarily on impact, which you feel as a sudden backwards yank on the pedals. The impact your suspension should be absorbing is instead transferred to both you and your frame. You wind up more tired and a lot less fast.

Taking inspiration from the new Demo, we moved the Enduro’s main pivot forward and raised the bike’s instant center, which minimizes rear wheel hang-up by giving the bike a more-rearward axle path in key stages of the wheel travel. Impact energy is transferred into the suspension, where it belongs, instead of into you. Voila, you just got faster.

we can all read the marketing blurb, but the reality is that the amount of rearward axle movement when the suspension compresses is about 2mm (ie not very much) for the demo and the enduro (and the trek rail that causes your leg to hurt) , and all that rearward movement is before the suspension reaches its sag point.

Go and have a look at a 2010 enduro, that had more (not hard to have more TBH ) rearward axle movement.

The rearward axle path is not why your leg hurts less on the enduro - I have no idea why your leg hurts less when on the enduro, but its not purely because the enduro has a (very slightly by 2mm , and before the sag point) rearward axle path.

Stop drinking the cool aid - as the yanks say.

 

[slippery pete]

Both of my bikes are setup properly.

Pound to a pinch, this is unlikely to be true.

 

[KnollyBro]

The bike I am referring to is the Specialized Enduro Comp pedal bike " none ebike"
Less Hang-Up, More Speed
If speed is your objective, square-edged bumps are your enemies. They cause your rear wheel to hang up momentarily on impact, which you feel as a sudden backwards yank on the pedals. The impact your suspension should be absorbing is instead transferred to both you and your frame. You wind up more tired and a lot less fast.

Taking inspiration from the new Demo, we moved the Enduro’s main pivot forward and raised the bike’s instant center, which minimizes rear wheel hang-up by giving the bike a more-rearward axle path in key stages of the wheel travel. Impact energy is transferred into the suspension, where it belongs, instead of into you. Voila, you just got faster.

If you are serious about getting some advice from the vast wealth of informed riders from around the world, it would really help to post a video of yourself, riding down a section of trail where you experience leg pain. Make sure it is a video of you riding the bike (not POV) so that your body position is clearly visible. You would need to show both bikes on the same section of trail.
I make videos all the time. You would be surprised what they reveal about what you think you are doing compared to what you actually are doing. If a picture is worth a 1000 words, a video must be worth more.

 

[Mikerb]

So you believe rearward wheel path is the holy grail.............what about wheel rate ( leverage ratio + shock compression ratio) and what that means in terms of digressive, linear and progressive rear suspension designs.

Interesting to note that you can effectively nullify the carefully worked out design by changing shock travel, shock tune, or simply not setting up the rear shock correctly.

Rear wheel hang up can be felt as a pedal kick ( or not depending on how good the rear suspension design is) and apart from wheel path and wheel rate other design criterea like anti squat (acceleration) and anti rise (braking) are effected by the compromise decided on in the rear suspension between pedal efficiency and rear wheel bump compliance/grip. Even such things as the freehub degree of engagement (smaller = potentially more pedal kick) what gear you are in, and what size chain wheel is being used make a difference.

The design of rear suspension is complex and always a compromise...but a compromise that best suits the type of riding the bike is prioritised to excel at. So a trail bike will not behave in the same way as an enduro bike............and examples of both can be either good or pretty poor.

 

[EMTB Rider]

Interesting comments. I'm confused, at this time, all I really know is that my Specialized Enduro Comp is less painful to ride chunky fast downhill trails. Its probably a combination of fitness and the bike geometry.