The Chainlink

Bike Fitting (BG) and Custom Bike Fitting

I am confused about bike fit. I am 6'1 and ride a 58cm Specialized Secteur Bike. I had a BG fit done and my stem shorted down to 90 mm to relieve some upper body back pain (originally 110) . The fit seemed to work. Recently I went to have a fit kit fitting done to explore having a steel touring bicycle built. I did the fit kit and learned I have about an 88cm pubic bone height and a lot of other measurement were taken.  After the fit, the bike fitter told me I had very short femur bones I think 16 inches or something like that . I was told I need a very steep seat tube angle to get my foot over the center of the peddle spindle. He suggested my present bike be modified with a zero offset seat tube and he moved my seat 2.5 cm forward and we added a 110 mm stem angled upward.

Ok I am very confused how does one bike fitter set me about 7cm aft of the bottom  (measuring bottom bracket through the center of the seat)bracket and another suggest a zero  offset tube and place  the saddle all the way forward.

I was told because of my short femur to get the ball of my foot over the spindle I need to bring my foot forward.  Still I could have sworn I had my foot over the spindle when the seat was back, and now have it over the spindle with the seat forward. The problem is I am pretty far forward on my bike now and it feels like I need to push my bars out even further.

I did some riding with the new position and got some pain on the lower outside of my left knee that I didn't have before. When I was on the fit kit machine it felt really great, but applied to my present bike it seems a bit weird. 

What confuses me more is I want the bike for touring. Is it normal to have a touring bike with a 75 degree seat angle? I guess I am sort of confused by bike fitting. 

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Permalink Reply by Gene Tenner on January 8, 2013 at 5:54pm

So, you fit more and your femur is far more fore more. Maybe you should adjust the mumbling shaft with kanuten valve and do what feels best to you with your own adjustments. Ride, adjust and repeat.

Permalink Reply by Doug Haynes on January 8, 2013 at 7:29pm

It is not just about having the ball of your foot over the pedal spindle it is about having your knee over the pedal spindle.

Bike fit is not a exact science like many would like to believe that it is.  Unless you are a competitive racer and/or setting bike up just to train/compete on there are not exactly solid rules on what does, or does not, fit properly.  To further confuse matters different shops/systems/people all have different opinions on what fits properly and is most comfortable.  There is no right answer on the subject; do a google search on bike fit and setup and you will find about eleventy-billion things out there half of which think all the others are wrong.

Take is all with a grain of salt and go with what your body tells you works.

Permalink Reply by Lanterne Rouge on January 8, 2013 at 7:37pm

a 75 degree STA is incredibly steep. Most touring or relaxed geometry bikes will have a STA angle between 72 and 73.5.

Are you all torso? I'm between 5'8 and 5'9 and have a PBH of 83cm.I think you should ride a couple of 60cm/62 cm frames; you might be pleasantly surprised.

Permalink Reply by Dave D on January 8, 2013 at 7:56pm

Thanks Jim I might just do that. I think I am going to take my road bike back to the way it was before with the regular tube not the zero offset and put the seat back.  When I do get that touring bike I think I will look at 60 cm perhaps. My inseam is 88cm I am 6'1 so I guess I have a bit of torso. I didn't even know my femur was way short for my height. 

Jim S said:

a 75 degree STA is incredibly steep. Most touring or relaxed geometry bikes will have a STA angle between 72 and 73.5.

Are you all torso? I'm between 5'8 and 5'9 and have a PBH of 83cm.I think you should ride a couple of 60cm/62 cm frames; you might be pleasantly surprised.

Permalink Reply by Dave D on January 8, 2013 at 7:57pm

Thanks Dug I have been googling the more I google the more confused I get. 

notoriousDUG said:

It is not just about having the ball of your foot over the pedal spindle it is about having your knee over the pedal spindle.

Bike fit is not a exact science like many would like to believe that it is.  Unless you are a competitive racer and/or setting bike up just to train/compete on there are not exactly solid rules on what does, or does not, fit properly.  To further confuse matters different shops/systems/people all have different opinions on what fits properly and is most comfortable.  There is no right answer on the subject; do a google search on bike fit and setup and you will find about eleventy-billion things out there half of which think all the others are wrong.

Take is all with a grain of salt and go with what your body tells you works.

Permalink Reply by Dave D on January 8, 2013 at 8:00pm

I misspoke I mean my knee or top of my tibia bone over the pedal spindle.

notoriousDUG said:

It is not just about having the ball of your foot over the pedal spindle it is about having your knee over the pedal spindle.

Bike fit is not a exact science like many would like to believe that it is.  Unless you are a competitive racer and/or setting bike up just to train/compete on there are not exactly solid rules on what does, or does not, fit properly.  To further confuse matters different shops/systems/people all have different opinions on what fits properly and is most comfortable.  There is no right answer on the subject; do a google search on bike fit and setup and you will find about eleventy-billion things out there half of which think all the others are wrong.

Take is all with a grain of salt and go with what your body tells you works.

Permalink Reply by Dave D on January 8, 2013 at 8:18pm

I just might do that.

Gene Tenner said:

So, you fit more and your femur is far more fore more. Maybe you should adjust the mumbling shaft with kanuten valve and do what feels best to you with your own adjustments. Ride, adjust and repeat.

Permalink Reply by Lanterne Rouge on January 8, 2013 at 8:43pm

What you're saying makes sense. 

I have the opposite problem; my femur is gargantuan and I need to be pretty far behind the bottom bracket to be comfortable. I imagine that if you were to ride a 60 or 62 cm touring bike, you could appreciate the comfort in a larger size. I had been riding 50-53 cm frames and riding a 57cm frame recently was a revelation.

Dave D said:

Thanks Jim I might just do that. I think I am going to take my road bike back to the way it was before with the regular tube not the zero offset and put the seat back.  When I do get that touring bike I think I will look at 60 cm perhaps. My inseam is 88cm I am 6'1 so I guess I have a bit of torso. I didn't even know my femur was way short for my height. 

Jim S said:

a 75 degree STA is incredibly steep. Most touring or relaxed geometry bikes will have a STA angle between 72 and 73.5.

Are you all torso? I'm between 5'8 and 5'9 and have a PBH of 83cm.I think you should ride a couple of 60cm/62 cm frames; you might be pleasantly surprised.

Permalink Reply by Dave D on January 8, 2013 at 8:46pm

I wish it wasn't so expensive to build a custom bicycle. 

Jim S said:

What you're saying makes sense. 

I have the opposite problem; my femur is gargantuan and I need to be pretty far behind the bottom bracket to be comfortable. I imagine that if you were to ride a 60 or 62 cm touring bike, you could appreciate the comfort in a larger size. I had been riding 50-53 cm frames and riding a 57cm frame recently was a revelation.

Dave D said:

Thanks Jim I might just do that. I think I am going to take my road bike back to the way it was before with the regular tube not the zero offset and put the seat back.  When I do get that touring bike I think I will look at 60 cm perhaps. My inseam is 88cm I am 6'1 so I guess I have a bit of torso. I didn't even know my femur was way short for my height. 

Jim S said:

a 75 degree STA is incredibly steep. Most touring or relaxed geometry bikes will have a STA angle between 72 and 73.5.

Are you all torso? I'm between 5'8 and 5'9 and have a PBH of 83cm.I think you should ride a couple of 60cm/62 cm frames; you might be pleasantly surprised.

Permalink Reply by We all have an inner Beast... on January 9, 2013 at 12:58am

Wouldn't the angles of the actual bike frame have some kind of influence as well? Did you change bikes? Do you change your riding "stance" (sorry, I don't know what it's called...maybe "position" ?) during the fitting as compared to when you actually pedal?

The bike that you will be having built, will it have the same angles as the one you ride now?

Those are just some questions that I would ask of myself....I have never had a "fitting" (maybe someday I will) and I just tinker around with it. Some years I am heavier, I have grown or shrunk. So, I have to make minor adjustments (seat more to the rear, seat height, seat angle, haven't changed anything else yet...LOL !) I just think that I need to be comfortable when I ride my bike. ( I guess being uncomfortable on my bicycle would make me ride faster, but I would be unhappy. And I have no clue how long I could really keep that "motivation" up...LOL!)

Everyone has given you some good advise on here, though.

Sort through it, and make the best possible decision.

Good luck with your new bike.

 

Respectfully,

Manny

Permalink Reply by Dave D on January 9, 2013 at 7:25am

I love the advice I get on this forum. Well, based on the machine I was fitted on we incorporated changes to my present bike which included a steeper seat tube and moving my saddle 2.5cm forward and a110 stem increase  from a 90mm stem angled upward. It may have worked on the machine where you could move the front in out to balance the seat angle, but on my present bike I got knee pain and it has drastically shortened my reach. I will probably go back to my original fitting. It doesn't mean a custom would not work, but it has left me sort of puzzled how different fitters have such different ideas on bike fit. My body has not changed. 

Permalink Reply by JMinHP on January 9, 2013 at 11:51am

If the builder is suggesting such a steep seat angle (75 degrees), visit a bike shop and try out a tri bike.  Tri bikes typically have steeper seat angles, usually anywhere between about 74 degrees and 80 degrees. Easy way to see if the fit might work before investing so much in a custom frame.

Dave D said:

I wish it wasn't so expensive to build a custom bicycle.

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