Fit changes to improve bike handling?

Discuss light weight issues concerning road bikes & parts.
zefs
Posts: 438
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

wintershade wrote:
Wed Jun 05, 2019 7:18 pm
Yes, I think KOPS was how fitter set me up. He made this whole big deal out of the process of starting at the foot and working up and everything sort of magiclly falling into place ("brining the bike to my body... not bringing my body to the bike"). He noted that he also moved my foot / cleat position a bit further forward (I think it was forward) because apparently this was somehow better for my knees given I have a history of patellofemoral syndrome, and would be more similar to optimal triathlete cleat position and riding position.

If you look at the picture, you can see my knee is pretty much right over the spindle.
He was correct except about the KOPS part which a lot of good fitters disagree with because it was an old method to estimate bike sizing and not a way to set bike position. So if your knee was ending up over the pedal spindle it was the right size (although there are so many other parameters like frame geometry and body proportions that it doesn't account for since it was an old method).

Karvalo
Posts: 737
Joined: Fri Aug 10, 2018 6:40 pm

by Karvalo

Lewn777 wrote:
Thu Jun 06, 2019 12:00 am
Too much weight over the front end will restrict your control and even fairly mild corner braking can cause low sides. In wet or dirt this is even worse. You can load the rear tire because your weight is over it, and you have to load it the rear to really excessive amounts before you high-side.
You appear to be saying that putting weight on the front of the bike will make it slide, but the rear wheel doesn't slide because your weight is on it. It doesn't make a huge amount of sense...

by Weenie


TobinHatesYou
Posts: 4175
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Really more weight on the front just means it gets adventurous when you hit a bump, slick patch, hole, etc. because those are sudden negative accelerations and you could get thrown forward. In fast downhill cornering situations on dry pavement, more weight forward and low is great...until you run over the pothole you didn't notice. And ideally not at the expense of keeping the rear planted.

mattr
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Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

Karvalo wrote:
Thu Jun 06, 2019 7:49 am
It doesn't make a huge amount of sense...
it doesn't make a huge amount of difference either. Unless you are riding a bike that is massively too small, or completely "off" (bicycle gymnastics bike for riding road or something similar).
It'd pretty much be unrideable in any realistic sense before the weight shift made *that* mutch difference to handling.
Maybe buying a too small road bike frame instead if a low profile frame of the right size might be the most likely scenario. Or sitting on the top tube.

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Lewn777
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by Lewn777

youngs_modulus wrote:
Thu Jun 06, 2019 1:04 am
Lewn777 wrote:
Thu Jun 06, 2019 12:00 am
Too much weight over the front end will restrict your control and even fairly mild corner braking can cause low sides.
The only thing that “causes” low-side crashes is a loss of adhesion at one or both tires. Excessive front braking while leaned over for a corner will cause your front wheel to wash out regardless of weight distribution. If you lose adhesion in the front on pavement, you pretty much get dumped immediately (as we all know). That’s a low-side crash.

If you lose adhesion at the rear tire, you can low-side as well as long as you don’t “catch” the slide. Deliberately laying your bike down (say, to avoid hitting a chain stretched across the road and three feet above it) usually involves locking your rear wheel as part of an intentional low-side crash.
Lewn777 wrote:
Thu Jun 06, 2019 12:00 am
In wet or dirt this is even worse. You can load the rear tire because your weight is over it, and you have to load it the rear to really excessive amounts before you high-side.
Your use of the term “load” is pretty vague here, but high-sides are the result of a stick-slip condition, not weight distribution. A sliding tire that suddenly grips (like when transitioning from glare ice to adjacent dry pavement) will pivot about the newly-grippy contact patch and throw the rider. That’s a high-side crash.
Yes, insufficient grip is the cause of cornering accidents . Caused by surface contamination fluids, dust, gravel, sand slight road imprefections and rider error such as braking too hard during the corner and incorrect weight balance.

All bikes have a a natural balance point built in from years of geometry refinement. You can go too far over the rear however nothing drastic happens other than you'll wheelie going uphill. Too far forward and you hamper control during cornering and increase the bikes inclination towards endos. For an average rider it's best to dail out the bike wanting to excessively wheelie uphill, but not go any further as this is evidence of being in a balanced sweet spot for handling.

WorkonSunday
Posts: 118
Joined: Tue Jan 16, 2018 4:39 pm

by WorkonSunday

if you are after a slightly more upright position without lots of spacers then V2r will be more suitable. V1r has an unusually long headtube, so much so the pro requested it to be shorten. hence in v2r it's about 5mm shorter but still very long for modern race bikes. on the other hand, most aero bikes have very short headtube to ensure the rider can get into very low/aggressive/aero position. if you head down the colnago route, make sure you check out and compared the geometries first, colnago has some weird, measurement system.... i normalyl ride a 54 for most brands, but i fit a 49s (A1r) and 50s (V1r).

try this website :thumbup: :

https://app.velogicfit.com/frame-comparison
In the house: Colnago V1r, Colnago A1r, Wilier Cento1 Air, Scott Scale 700SL, Bianchi FSE, Colnago Concept, Colnago A1r, Specialized Ruze Pro, Wilier GTR, Argon 18 E117 Tri+, Brompton B75

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Lewn777
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Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

Karvalo wrote:
Thu Jun 06, 2019 7:49 am
Lewn777 wrote:
Thu Jun 06, 2019 12:00 am
Too much weight over the front end will restrict your control and even fairly mild corner braking can cause low sides. In wet or dirt this is even worse. You can load the rear tire because your weight is over it, and you have to load it the rear to really excessive amounts before you high-side.
You appear to be saying that putting weight on the front of the bike will make it slide, but the rear wheel doesn't slide because your weight is on it. It doesn't make a huge amount of sense...
I'm saying that too much weight over the front of the bike will screw up the bikes handling. The front wheel and rear wheel behave totally differently. You can grab handfuls of rear brake and you'll leave an easily controllable black line. You grab hanfulls of front brake in the dry on a straight good road in the right way you'll endo, do it wrong and the bike will slide in a very unpredictable way and be prone to becoming effected by any inconsistency in the road surface. Do it on a contaminated surface or corner you'll get road rash.

Surely that indicates that a front wheel and rear wheel have a totally different effect. Bicycle geometry has evolved over time to put us in a balanced position over our wheels with a rear bais. Surely you can see that extra weight on the rear tire will have minimal effect on the bikes handling but under-loading or over-loading the front tire can cause problems?

This is why moto GP riders spend hours deciding what compound and tire pressure they want to use, why mountain bikes now run different compounds, wheel diameters, widths, treads and pressures front and rear. Theres an idea floating around road bikes that front and rear tires need to match symmetrically, pressure, brand and compound, but actually it's nonsense.

TobinHatesYou
Posts: 4175
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Lewn777 wrote:
Thu Jun 06, 2019 9:37 am

I'm saying that too much weight over the front of the bike will screw up the bikes handling. The front wheel and rear wheel behave totally differently. You can grab handfuls of rear brake and you'll leave an easily controllable black line. You grab hanfulls of front brake in the dry on a straight good road in the right way you'll endo, do it wrong and the bike will slide in a very unpredictable way and be prone to becoming effected by any inconsistency in the road surface. Do it on a contaminated surface or corner you'll get road rash.

Surely that indicates that a front wheel and rear wheel have a totally different effect. Bicycle geometry has evolved over time to put us in a balanced position over our wheels with a rear bais. Surely you can see that extra weight on the rear tire will have minimal effect on the bikes handling but under-loading or over-loading the front tire can cause problems?

We're all still confused by what you are trying to say here.

More weight on the front tire means more grip, means you're less likely to go fwooop and hurt yourself. More weight on the front tire also means less weight on the rear tire, which isn't a huge a consequence because rear skids are generally recoverable.

It's extra confusing that you keep mentioning putting more weight on the rear tire and it having minimal effect. Who cares? You also can't really overload a tire ...you can however underload the other tire. I would certain prefer to "overload" the front tire if "perfect balance" is not a multiple choice option. That way the rear starting to slide is a warning to slow down.

This of course doesn't account for suddenly hitting a stone or pothole and being so far forward that you get thrown even more forward on your bike all the while accidentally steering your bars in the process. That is a very realistic situation.

zefs
Posts: 438
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

TobinHatesYou wrote:
Thu Jun 06, 2019 9:48 am
This of course doesn't account for suddenly hitting a stone or pothole and being so far forward that you get thrown even more forward on your bike all the while accidentally steering your bars in the process. That is a very realistic situation.
Another reason weight distribution and balance plays a big role. Since I switched to more saddle setback hitting bumps doesn't push me out of the saddle's sweet spot as much, usually it would through me in the front as mentioned and I had to always swift back.

Karvalo
Posts: 737
Joined: Fri Aug 10, 2018 6:40 pm

by Karvalo

Lewn777 wrote:
Thu Jun 06, 2019 9:37 am
Karvalo wrote:
Thu Jun 06, 2019 7:49 am
Lewn777 wrote:
Thu Jun 06, 2019 12:00 am
Too much weight over the front end will restrict your control and even fairly mild corner braking can cause low sides. In wet or dirt this is even worse. You can load the rear tire because your weight is over it, and you have to load it the rear to really excessive amounts before you high-side.
You appear to be saying that putting weight on the front of the bike will make it slide, but the rear wheel doesn't slide because your weight is on it. It doesn't make a huge amount of sense...
I'm saying that too much weight over the front of the bike will screw up the bikes handling. The front wheel and rear wheel behave totally differently. You can grab handfuls of rear brake and you'll leave an easily controllable black line. You grab hanfulls of front brake in the dry on a straight good road in the right way you'll endo, do it wrong and the bike will slide in a very unpredictable way and be prone to becoming effected by any inconsistency in the road surface. Do it on a contaminated surface or corner you'll get road rash.

Surely that indicates that a front wheel and rear wheel have a totally different effect. Bicycle geometry has evolved over time to put us in a balanced position over our wheels with a rear bais.
None of that is what you originally said.
Surely you can see that extra weight on the rear tire will have minimal effect on the bikes handling but under-loading or over-loading the front tire can cause problems?
Apart from by getting fatter, how do you put more weight on the rear tyre without progressively underloading the front tyre?

dricked
Posts: 184
Joined: Tue Jan 09, 2018 1:57 pm

by dricked

Nevermind

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Lewn777
Posts: 833
Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

TobinHatesYou wrote:
Thu Jun 06, 2019 9:48 am
Lewn777 wrote:
Thu Jun 06, 2019 9:37 am

I'm saying that too much weight over the front of the bike will screw up the bikes handling. The front wheel and rear wheel behave totally differently. You can grab handfuls of rear brake and you'll leave an easily controllable black line. You grab hanfulls of front brake in the dry on a straight good road in the right way you'll endo, do it wrong and the bike will slide in a very unpredictable way and be prone to becoming effected by any inconsistency in the road surface. Do it on a contaminated surface or corner you'll get road rash.

Surely that indicates that a front wheel and rear wheel have a totally different effect. Bicycle geometry has evolved over time to put us in a balanced position over our wheels with a rear bais. Surely you can see that extra weight on the rear tire will have minimal effect on the bikes handling but under-loading or over-loading the front tire can cause problems?

We're all still confused by what you are trying to say here.

More weight on the front tire means more grip, means you're less likely to go fwooop and hurt yourself. More weight on the front tire also means less weight on the rear tire, which isn't a huge a consequence because rear skids are generally recoverable.

It's extra confusing that you keep mentioning putting more weight on the rear tire and it having minimal effect. Who cares? You also can't really overload a tire ...you can however underload the other tire. I would certain prefer to "overload" the front tire if "perfect balance" is not a multiple choice option. That way the rear starting to slide is a warning to slow down.

This of course doesn't account for suddenly hitting a stone or pothole and being so far forward that you get thrown even more forward on your bike all the while accidentally steering your bars in the process. That is a very realistic situation.
Karvalo wrote:
Thu Jun 06, 2019 8:51 pm
Lewn777 wrote:
Thu Jun 06, 2019 9:37 am
Karvalo wrote:
Thu Jun 06, 2019 7:49 am
Lewn777 wrote:
Thu Jun 06, 2019 12:00 am
Too much weight over the front end will restrict your control and even fairly mild corner braking can cause low sides. In wet or dirt this is even worse. You can load the rear tire because your weight is over it, and you have to load it the rear to really excessive amounts before you high-side.
You appear to be saying that putting weight on the front of the bike will make it slide, but the rear wheel doesn't slide because your weight is on it. It doesn't make a huge amount of sense...
I'm saying that too much weight over the front of the bike will screw up the bikes handling. The front wheel and rear wheel behave totally differently. You can grab handfuls of rear brake and you'll leave an easily controllable black line. You grab hanfulls of front brake in the dry on a straight good road in the right way you'll endo, do it wrong and the bike will slide in a very unpredictable way and be prone to becoming effected by any inconsistency in the road surface. Do it on a contaminated surface or corner you'll get road rash.

Surely that indicates that a front wheel and rear wheel have a totally different effect. Bicycle geometry has evolved over time to put us in a balanced position over our wheels with a rear bais.
None of that is what you originally said.
Surely you can see that extra weight on the rear tire will have minimal effect on the bikes handling but under-loading or over-loading the front tire can cause problems?
Apart from by getting fatter, how do you put more weight on the rear tyre without progressively underloading the front tyre?
More weight on the front of a bicycle gives you more grip on a good dry road on a straight line under braking. If you are going around a corner or the road surface is contaminated and your weight is too far forward due too hard braking and/or incorrect bike position you are more likely to crash or have control issues.

Straight out of beginners mountain bike technique article:

How to Brake

Braking should be consistent and controlled. Most of your braking power comes from your front brake, but grabbing a handful of front brake will send you over the bars. Instead, lightly apply the brakes, and do so evenly on the front and back brakes (you can ignore this for road bikes you only really need front brake). Avoid sudden, fast squeezes to help prevent skidding.

PLEASE READ:
While braking, brace yourself by moving your hips back, dropping your heels down and keeping a slight bend in your knees and elbows. This body position helps you stay in control and from getting too far forward on the bike.


It's exactly what I've been trying to consistently say all along. Maybe my communication style isn't accurate or people are trying to deliberately misunderstand.

Try some reading: A Twist of the Wrist 2 by Keith Code, Sport Riding techniques by Nich Ienatsch or Mountain Bike! by William Nealy (not that good but some basic info). Obviously anything to do with the effect of an engine isn't relevant so you'll have to ignore some of the information and some of the mountain bike stuff is outdated. However I've never read a book for bicycle road riding technique, let alone seen one. Plenty on maintenace. :roll:

Karvalo
Posts: 737
Joined: Fri Aug 10, 2018 6:40 pm

by Karvalo

Lewn777 wrote:
Thu Jun 06, 2019 10:36 pm
How to Brake

Braking should be consistent and controlled. Most of your braking power comes from your front brake, but grabbing a handful of front brake will send you over the bars. Instead, lightly apply the brakes, and do so evenly on the front and back brakes (you can ignore this for road bikes you only really need front brake). Avoid sudden, fast squeezes to help prevent skidding.

PLEASE READ:
While braking, brace yourself by moving your hips back, dropping your heels down and keeping a slight bend in your knees and elbows. This body position helps you stay in control and from getting too far forward on the bike.[/b]

It's exactly what I've been trying to consistently say all along. Maybe my communication style isn't accurate or people are trying to deliberately misunderstand.
No, you were talking about handling, that article is talking about straight line braking. It is entirely inconsistent of you to conflate the two. After all, a wise man once said "But don't confuse braking with handling." Who was that man, Lew?

Discodan
Posts: 146
Joined: Mon Oct 16, 2017 2:55 am

by Discodan

Agree, braking and cornering traction are getting confused here. In terms of pure traction for cornering, having more weight on the front improves both traction and feel.

It’s a lot more obvious on a MTB where you are regularly sliding either end but if you have your weight too far back the front will tend to wash out and is not confidence inspiring.

Likewise on motorbikes, putting more weight over the front helps cornering and really lets you brake deeper and later into corners


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by Weenie


dricked
Posts: 184
Joined: Tue Jan 09, 2018 1:57 pm

by dricked

Weighting the front of a motorcycle doesn’t help with braking or turn in. When you apply the brakes you change the geometry of the bike and also flatten the tire increasing the contact patch. You want to move your body weight back to help keep the bike from lifting the rear tire and it also helps with not overloading the front tire when trail braking.

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