BG fit – mixed feelings

When drugs don't work: training and health tips!
lef
Posts: 672
Joined: Sun Jun 20, 2010 12:31 pm

Re: BG fit – mixed feelings

Postby lef » Thu Nov 29, 2012 21:17 pm

ALIHISGREAT wrote:
lef wrote:
ALIHISGREAT wrote:
Herbsman wrote:Shouldn't the bike adjust to the rider, not vice versa?

My bike fit (not BG) felt good straight away.


No.

You ride for however many miles (not an insignificant number) in the wrong position.. so your body adapts to this position and muscles become accustomed to working in that position.

You then get put in a bio-mechanically correct position.. and your body has to adjust back.

If you fit the bike to someone who is adjusted to a bad position.. you end up in a bad position.


When I had my bike fit my saddle went up ~4cm too.. taking me to 28degrees leg extension -> back of the knees didn't feel right for the first few rides.. then it settled down.


A correct position for a rider should not create discomfort, and in my view if it does it is not correct for the rider at that given time and worse case cause injury. A fit intending to achieve a comfortable position for a rider needs to understand the riders comfortable range of motion, weaknesses and so on, at the time of the fit and allow for them. The bike is then adjusted to suit this.


Ok so lets use a theoretical example...

I have a bad position on the bike -> leg extension is way off, and this is causing my hamstrings and calves to tighten up as my leg isn't straightening enough, and there is likelihood of knee pain due to too much stress on the knees.

I then get put in a proper position on the bike with leg extension at around 30degrees... the previous tightness in my hamstrings and calves now puts more pressure on my back.. and I get back pain.


What should we do in this situation? According to you we keep the bad fit? which is biomechanically incorrect and will cause problems down the road with the knees (if its not already causing problems).

According to me.. we use the new fit which is correct.. then we solve the back problem at the root of the cause. (which is likely to be contributed to be the poor bike fit anyway)


I would suggest gradual changes if creating discomfort / pain and make the changes in addition to an off the bike flexibility & core program. A good fitter will say come back for further consultation if you are experiencing any problems, not suggest you continue to ride through the pain, and dont worry it will go away soon enough. If someone has been riding for years in the wrong position why the urgency to suddenly shoehorn them into the 'perfect' position.

lef
Posts: 672
Joined: Sun Jun 20, 2010 12:31 pm

Re: BG fit – mixed feelings

Postby lef » Thu Nov 29, 2012 21:24 pm

Herbsman wrote:GO back to Specialized and explain that your new position is uncomfortable.


Absolutely. Get back there. They may suggest to reduce the changes by a half for a few rides so less of a jump (if the changes were significant)

mamba80
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Joined: Fri Nov 06, 2009 13:06 pm

Re: BG fit – mixed feelings

Postby mamba80 » Fri Nov 30, 2012 08:33 am

Setarkos wrote:BG Fit's 30 degree figure is definitely one of the lowest among bike fitters, so they do put you quite high. I would try it for at least 10 rides and if pedalling doesn't become smoother go back by 5-10mm.


I understood the 30 degree knee angle puts you quite low on the bike? not high - 25 to 30 being a normal range if using knee angle to set seat height.

the changes the OP has had ie 4.5cm, 4cm and 1.5cm increases in reach, height and setback are huge, so hardly surprising it feels odd - BG fits arnt cheap so go back and ask for a 2nd fitting ?

Simmo72
Posts: 200
Joined: Wed Jun 02, 2010 11:51 am

Re: BG fit – mixed feelings

Postby Simmo72 » Fri Nov 30, 2012 12:35 pm

GiantMike wrote:If you got another BG bike fitting (at a different shop or with a different bike fitter) would you get a different result?

Do you think the fitting system was correctly applied and it didn't suit you, or was the fitting system incorrectly applied?

A good question but I think the fitting was carried out correctly using the BG science, I've spoken to a couple of friends who have had the same assessment and all the same checks were made. Its a very set routine with BG, I'm not slating the process, I'm sure it works for the majority.

Simmo72
Posts: 200
Joined: Wed Jun 02, 2010 11:51 am

Re: BG fit – mixed feelings

Postby Simmo72 » Fri Nov 30, 2012 12:40 pm

mamba80 wrote:
Setarkos wrote:BG Fit's 30 degree figure is definitely one of the lowest among bike fitters, so they do put you quite high. I would try it for at least 10 rides and if pedalling doesn't become smoother go back by 5-10mm.


I understood the 30 degree knee angle puts you quite low on the bike? not high - 25 to 30 being a normal range if using knee angle to set seat height.

the changes the OP has had ie 4.5cm, 4cm and 1.5cm increases in reach, height and setback are huge, so hardly surprising it feels odd - BG fits arnt cheap so go back and ask for a 2nd fitting ?


Put it this way, with the seat as the new height my toes can't touch the floor (and I'm a size 48), femur length has an impact on leg angle. I had a go on the rollers last night with 1cm lower and 2-3mm futher forward and it felt more comfortable, should hopefully find out more tomorrow.

Setarkos
Posts: 234
Joined: Sun Oct 16, 2011 09:39 am

Re: BG fit – mixed feelings

Postby Setarkos » Fri Nov 30, 2012 14:26 pm

mamba80 wrote:
Setarkos wrote:BG Fit's 30 degree figure is definitely one of the lowest among bike fitters, so they do put you quite high. I would try it for at least 10 rides and if pedalling doesn't become smoother go back by 5-10mm.


I understood the 30 degree knee angle puts you quite low on the bike? not high - 25 to 30 being a normal range if using knee angle to set seat height.

the changes the OP has had ie 4.5cm, 4cm and 1.5cm increases in reach, height and setback are huge, so hardly surprising it feels odd - BG fits arnt cheap so go back and ask for a 2nd fitting ?


Where did you get that information? Normal recommendations are afaik around 35°. 30° as used by BGFit is the lowest figure I know from any BikeFit and of all the people I know who had the BGFit, every single one was put higher on the bike.
The angle they measure 180-knee angle.

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ALIHISGREAT
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Re: BG fit – mixed feelings

Postby ALIHISGREAT » Fri Nov 30, 2012 17:35 pm

Setarkos wrote:
mamba80 wrote:
Setarkos wrote:BG Fit's 30 degree figure is definitely one of the lowest among bike fitters, so they do put you quite high. I would try it for at least 10 rides and if pedalling doesn't become smoother go back by 5-10mm.


I understood the 30 degree knee angle puts you quite low on the bike? not high - 25 to 30 being a normal range if using knee angle to set seat height.

the changes the OP has had ie 4.5cm, 4cm and 1.5cm increases in reach, height and setback are huge, so hardly surprising it feels odd - BG fits arnt cheap so go back and ask for a 2nd fitting ?


Where did you get that information? Normal recommendations are afaik around 35°. 30° as used by BGFit is the lowest figure I know from any BikeFit and of all the people I know who had the BGFit, every single one was put higher on the bike.
The angle they measure 180-knee angle.


The acceptable range for the Trek fit I had done was 25-35degrees.

mamba80
Posts: 2415
Joined: Fri Nov 06, 2009 13:06 pm

Re: BG fit – mixed feelings

Postby mamba80 » Fri Nov 30, 2012 18:10 pm

25 to 35 is what my 2 bike fitting friends use and the 30 to 35 is reserved for folk with issues.
One is an ex BG fitter who rides way higher than 30' probably 25'
Or another way 145 to 155' knee angle relative to full leg extention.

If the op cannot even touch the ground at all then i suggest his original knee angle is probably more in the region of 20 to 25' and the heel drop was wrong when they set the 30' in the first place.

Setarkos
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Joined: Sun Oct 16, 2011 09:39 am

Re: BG fit – mixed feelings

Postby Setarkos » Fri Nov 30, 2012 18:56 pm

Okay my apologies, seems to be a fairly recent development though. Gave it a quick google and most sources are between 27 and 37 degrees... but I found an article suggesting what you said.

I suspect that the different figures result from different methods of measurement...
BGFIt (and all other bike fits I know) measure from the hip bone through the knee joint to the ankle and I am pretty sure that recommendations for that method range from 30 to 40 degrees.


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