rosinante25

i ride two bikes presently. my regular everyday is a specialized secteur and my rain bike is a moto cafe sprint that started life as a flatbar which i have put drops on. i'm not sure this can possibly be true but it seems that when i ride the moto i hurt either my knees or my achilles. when i ride my secteur there r no problems except for an occasional back ache. when i hurt my achilles i lower the seat and then i seem to hurt my knees. can it be that the more "hybrid" geometry of the moto causes the injuries? the moto is also slightly shorter than the elite. does this contribute to it? i'd hate to give up riding the moto but i'm getting tired of the problem. anybody have a similar experience or is it all a coincidence and in my head?

Rowan

Get a tape measure and a plumb bob. Do a measurement check on both bikes -- that includes sitbone position to handlebar hand position, pedal at the bottom of the stroke to the sitbone position, crank length and knee-over-pedal spindle.

In general, if all these measurements are identical, it's irrelevant what the geometry of the bikes is different (if you are referring to seat tube angle, head angle, wheelbase, etc).

I'd be almost inclined to suggest that there is a difference in your crank length between the two bikes. but without that data (as mentioned above) it's very, very difficult to give a diagnosis.

berner

I suspect Rowan is right in suggesting that whatever the difference between the two bikes, careful measurement will will reveal the difference and that will suggest a solution. One difference I can think of is that a more upright position will shift center of gravity aft while in a drop bar position the center of gravity is close to being over the bottom bracket. What this might have to do with knees, I don't know.

Rowan

The issue with knees and achilles tendon strongly suggests seat height, and that's why I have thrown crank length into the mix

NOS88

Yes, I suspect this is the primary area to investigate. Sometimes fore/aft saddle position can put the knees to far forward or back. This could cause similar knee / achilles tendon issues. But careful measurement of the two bikes is a good place to start.

stonefree

It's nice if you have multiple bikes, then you can use the one with the best fit (least painful rider) as a template to take the measurements from.

OldsCOOL

Can geometry cause injury?

I dont know but I've had severe headaches in Algebra.

RonH

Here's a chart/article that tsl referred me to a few months ago. You can use it to compare the geometry on both bikes. Thanks tsl.


When I saw the thread topic my first thought was, "High school geometry nearly caused my brain to explode".

AzTallRider

I have a friend who just sold the frame of his racing road bike, and is replacing it with something else, because he always feels "beat up" after riding it. This is despite the fact that it was fitted, by a pro, exactly the same as his custom Serotta, which doesn't cause the problems. He attributes it to flex, but nobody is sure what is causing the issues. He finally just gave up, and is going with something else (a Madone 6.9). There is more to ride than geometry.

alanknm

Flex, vibration damping of road buzz or the lack of it, geometry are all contributors to ride quality.

The same setup would indicate that feeling of being beat up is more from vibration fatigue. The OP's problem would seem to me to be a question of fit.

JimTjr

The importance of "FIT" is made fairly obvious on here many times. It would seem you have a fit problem with the MOTO,,, What alanknm said above, the frame, and difference in the bikes would cause some problems, but NOT pain like your feeling. Those are injury potentials I think.

tsl

Hey, Ron! How did that work out for you? I lost track of that thread.

AzTallRider

How much of an adjustment are you making: millimeters? centimeters? inches?

RonH

After swapping the handlebar ($15 from Jenson), tires (Conti GP4000 I had in the shed) and stem (replaced with a zero degree - $20) it rides great. Thanks.
Here it is.

fietsbob

I'd watch those sharp points on some of those old fashioned drafting lay out tools.
the pointy ends of a compass, and dividers , particularly.

Rowan

Sorry Ron, but for me, that outer chainring is just plain... ugly and really hurts the look of a nice bike.

tsl

Hey now, Rowan. Didn't your mother ever teach you that if you can't say something nice, don't say anything at all?

You'll notice I've said nothing at all about the aesthetic of the Ultegra 6700 crankset I put on my Litespeed. I also avoid looking at the bike's drive side.

lphilpot

I guess I'm different. I had exponentially more trouble with algebra than geometry in high school, no pun intended.

RonH

It's the SRAM Apex stuff that came on the bike. Too expensive to swap. My main ride (my wonderful Litespeed ) is full Ultegra.

RonH

I got A's in algebra. I loved it. Got a D in first semester geometry. Managed to escape with a C- in the second semester.

rosinante25

rowan, i checked out the crank lengths and found that the secteur's are 172.5 and the moto's 175. this may be the solution. previously i had my lbs mirror the two bikes in fit and altho the problems diminished they were still there with the moto. i had knees and achilles injuries in the past from sports so maybe i just need the easier cranks. i'll take the bike in to the shop & c if i need to change the gearing as well along with the cranks. thanx so much guys. i hope this is it.

oh & yeah i guess geometry isn't the culprit except maybe in school.

JimTjr

So, I am confused,, just how does the looks of the chain ring help this gentleman figure out why he has discomfort between the two bikes??

I guess some people don't communicate well, or maybe don't read so good? Maybe he thought the OP was asking how his bike looked? I don't know,,,,

Rowan

Jim, have you ever participated in a verbal conversation where there were more than one topic?

Around here, it's like a chat at the pub. Someone asks a question, someone uses an illustration to support what they say and, oh look, that's a bit odd/silly/great/fantastic, there's a little side topic goes on, then when the person asks the original question comes back with some more info, we continue where we left off.

billydonn

My money is on this.

John_V 

+1