Login required to started new threads

Login required to post replies

Bike fit question
Quote | Reply
Hi all,

I got a digital camera for Xmas and have been using the self-timing feature to take pictures of myself on the tri-bike... trying to see if I am in a correct position. I've been to the slowtwitch bike fit section and to bikesports bike fit page and have left a little confused. Near as I can tell, when the pedals are at 6 o'clock, Demerly thinks my femur and shoulder to hip joint should make a 90 degree angle while Empfield thinks my hip joint to pedal axle and shoulder to hip joint should make a 90 degree angle. Which is it?

Also, Demerly criticizes positions as being "too high on the bike" and too "upright." Are these synonyms? If not, what is "high?"

(For those who are really motivated to help me out, check out [url] http://meg.nscteam.com/bike.htm [/url] where I've attempted to compare my fit to one of Demerly's favoirte.)

Thanks,

Meg.
Last edited by: Meg: Jan 6, 03 7:39
Quote Reply
Re: Bike fit question [Meg] [ In reply to ]
Quote | Reply
Looks okay to me. Do you work on any flexibility exercises? I would not say that you are too high on the bike, especially compared to some I have seen.

I would consider seeing a qualified fitter to confirm this, however.
Quote Reply
Re: Bike fit question [Meg] [ In reply to ]
Quote | Reply
what you descibe as the divergence between my view and tom's is really quite small. we're both saying almost the same thing, and when you take into account the range of 3cm in armrest drop in my formulae, the more aggressive side of that range would pretty-much correspond with what tom's site espouses.

Dan Empfield
aka Slowman
Quote Reply
Re: Bike fit question [Meg] [ In reply to ]
Quote | Reply
Hi Meg, I looked at your photo (thanks for providing the URL)and I thought, based strictly on what I see from the photo, that your position is very good- perhaps approaching optimal or at optimal- it's tough to say from just a photo. When I fit someone I do it in a "dynamic" setting where they are pedalling on an indoor trainer. It is worth noting (and giving credit) to Dan for his fitting innovations and insights. I am not a contemporary of Dan Empfield, but rather an honored student of his. The majority of what we use to fit a (triathlete) person here at Bikesport we learned from Dan Empfield or from people who learned it from him. I'm attending his fit clinic in February along with a couple other guys from the store. Dan's ability to analyze problems and approach fit without an attachment to previous paradigms (while maintaining a knowledge and respect for them) is a powerful resource to us. Put it this way- one of the resons I'm going to the fit clinic is for Dan to look at MY position. I wish we could see yours in person, but it looks like you have done an excellent job and are also sensitive to the importance of your position. I say good job. Perhaps my one question or observation is that you do pedal at what appears to be the outer (long) limit of leg extension: Again, just a casual observation- tough to tell without seeing the pedal stroke and measuring the joint angle in person.

Tom Demerly
The Tri Shop.com
Quote Reply
Re: Bike fit question - active front view?[Tom Demerly] [ In reply to ]
Quote | Reply
I can't help but notice the emphasis on a side view for fitting... when I was first fitted some 13-14 yrs ago (and one other time since then), my fitter concentrated on FRONT view as much as the side view (using a videocam - pretty hi-tech for the time).

Unfortunately, from what I gather by what I read and see posted on sights the concentration is too much on those issues surrounding seat height, H.bar height, crank lenghth, frame size and how it relates to a side profile fit. In my opinion, frontal views provide as much information as does side views. By that I mean, many ITB problems (solved with orthodics) are issues of vertical knee movements and less with knee angle.

IMHO, front view video camera shots provide a much need addition to the total bike fit. As for efficiency, it is what the wind hits first that determines that element which defines resistance. In other words, increase frontal surface area means more resistence. Whether or not this is excessively simplistic, I think those in "aero-dynmanic" know could be a much better judge. But, from a fit standpoint...I think a look at a biker while in motions FROM THE FRONT would be a notable advantage. And, yet I see only side pictures emphasized.

FWIW Joe Moya
Quote Reply
Re: Bike fit question - active front view? [Joe M] [ In reply to ]
Quote | Reply
Again, this is why I don't think you can do it from photos.

Tom Demerly
The Tri Shop.com
Quote Reply