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-   -   new drive train and knee pain (http://www.bikeforums.net/general-cycling-discussion/776416-new-drive-train-knee-pain.html)

chandltp 10-19-11 12:50 PM

new drive train and knee pain
 
So a month or two ago, I got an entirely new drive-train put on my bike. New bottom bracket, cranks, front chain-rings, and cassette (from a freewheel), and new wheel.

The following weekend I had a charity ride that I rode two and from. For the first time ever, I had knee pain by the end of the ride.

I've played with the seat height, but it was marked so they got it back reasonably close. Nothing else has changed on the bike.

I've tried suspending my morning recreational rides for the last 2 weeks (the rain helped that choice) with no improvements. I've stopped doing the stretched for my hip pain for about a month now (I started those about the same time).

I still commute 2 miles to work, but I wouldn't think that would be enough to prevent healing. It's nice and flat.

Should I stop commuting and see if it gets better? Just walk? Any other suggestions? Is it possible there's something minorly different about the drive-train that requires another adjustment on my bike?

Editted to add:

It was a Trek 7000 with all stock parts. The LBS put on a Shimano Hyperdrive set on the front. Don't know if that matters.

Nightshade 10-19-11 12:54 PM

Did you change the cranks in any way? Somehow you've changed the geometry of your pedal stroke and your legs/knees don't like the change.

fietsbob 10-19-11 01:07 PM

You trying to push a big gear to go fast? spin a lower one ,
and stay on top of the gear.
Accept the slower pace, ... in fact savor it.
the spin does not have to be fast, just enough to feel like it's a light pedal effort.

tagaproject6 10-19-11 01:57 PM

Crank arms change in length? Cleat position...toe-in, toe-out, farther back, too far forward??

chandltp 10-19-11 01:59 PM

Quote:

Originally Posted by Nightshade (Post 13386707)
Did you change the cranks in any way? Somehow you've changed the geometry of your pedal stroke and your legs/knees don't like the change.

Yea, I just don't know how. The cranks were changed, but I assume they would have put on the same length, but are there other variable to cranks?

chandltp 10-19-11 02:00 PM

Quote:

Originally Posted by fietsbob (Post 13386777)
You trying to push a big gear to go fast?

Pedaling the same I have been for the last 2 years, as far as I can tell. Still as slow as ever.

chandltp 10-19-11 02:02 PM

Quote:

Originally Posted by tagaproject6 (Post 13387088)
Crank arms change in length? Cleat position...toe-in, toe-out, farther back, too far forward??

Sounds like I need to go ask the bike shop what the differences might be between the cranks they put on an the ones they replaced. I didn't think it was possible for such a small change to make a difference, but it sounds like it is so I'll go ask.

No cleats to deal with, same platforms I had before.

Editted to add: Might be a couple days before I make it in. I dislike running errands while it's raining. Don't mind the commute, but I hate coming back out and getting on a wet bike.

chandltp 10-19-11 02:13 PM

I forgot to mention, that it seems to alternate between knees.

the_freewheeler 10-21-11 12:11 AM

There is no way to compare it with this test since it has already been switched out, but do this to check on the crank length and seat position...

1. Sit on the bike in a stationary position (a trainer is ideal, holding onto a door frame or having a friend hold you up works too).
2. Place your feet on the pedals as you would normally ride with your platforms.
3. Rotate the crank to be parallel with the ground and hold a plumb bob on the front of your knee cap (if no plumb bob try to look closely at your knee position in relation to the toe of your foot).

If you were to drop a plumb bob, the cap of your knee should be aligned with the front of your foot. This is one theory and it works for many for fitment as a general rule and can easily be tested at home. Good luck!

chandltp 10-21-11 05:49 AM

Quote:

Originally Posted by bowermb (Post 13394139)
If you were to drop a plumb bob, the cap of your knee should be aligned with the front of your foot. This is one theory and it works for many for fitment as a general rule and can easily be tested at home. Good luck!

Thanks, I should have mentioned that I've already checked this. It doesn't seem any different, but as you said, I don't have the old setup to compare it to. I'm hoping to make it into the bike shop tomorrow (time permitting), and hopefully we can look at a stock Trek 7000 and see what might be different. At the very least, I might be able to eyeball the differences. I think once I know that it will give me a good idea what adjustments to make (unless the width between the pedals changed or something that I can't correct)

work4bike 10-21-11 06:19 AM

Cycling is a very repetitive activity and can lead to muscle imbalance, because it uses some quite a bit in comparison to others. Do you do any other type activity? I'm pretty active and also hike and run, but I keep my body strong by weightlifting in order to ensure all the muscles/tendons/legiments are exercised. I started weightlifting because I use to have really bad knee pains years ago, which I blame on my cycling; I'm also a commuter, making cycling my primary activity.

Of all the times I've changed out my drivetrains I've never experienced knee pains, nor from bike changeouts, so I'd recommend looking at other activities to work parts of the body that are somewhat ignored by cycling.

chandltp 10-21-11 10:34 AM

Quote:

Originally Posted by john gault (Post 13394540)
Do you do any other type activity?

Home improvement. I really want to get back into weight lifting again, but I can't seem to develop a good habit with that.

I have 3 or 4 bikes I swap and I only briefly had a problem last winter when I switched to my winter bike.

triumph.1 10-21-11 11:06 AM

if everything is the same except the new crank. Read the length on the inside of each arm. You may have been given longer crank arms than you had previously. I recently went from 175 down to 172.5 and that made a big difference in a good way for me. The 175's were a bit stressful on my old knees. If your shoes are the same the seat is the same there isn't much else that could cause a sudden difference.

cleon 10-21-11 11:18 AM

+1

I ride 170s on my road bike and bought a used mtn bike with 175s, and they are killing my knees (I noticed it immediately - just felt way too wide of a diameter stroke). Going to replace them asap. Might even try to find 165s for the my road bike based on all of the calculators I see out there. Anyway, that's the first thing I would check to see if it changed.

Quote:

Originally Posted by triumph.1 (Post 13395701)
if everything is the same except the new crank. Read the length on the inside of each arm. You may have been given longer crank arms than you had previously. I recently went from 175 down to 172.5 and that made a big difference in a good way for me. The 175's were a bit stressful on my old knees. If your shoes are the same the seat is the same there isn't much else that could cause a sudden difference.


deep_sky 10-21-11 12:15 PM

Your q-factor (basically your stance, how wide apart your feet are) might have changed too. Not all cranksets are equal in this regard.

cleon 10-21-11 12:21 PM

Is this typically published in the crank specs?

Quote:

Originally Posted by deep_sky (Post 13396020)
Your q-factor (basically your stance, how wide apart your feet are) might have changed too. Not all cranksets are equal in this regard.


hybridbkrdr 10-21-11 01:44 PM

Quote:

Originally Posted by cleon (Post 13396060)
Is this typically published in the crank specs?

I read once road cranks are closer to the frame while mountain cranks are wider. I don't know if they publish that information.

If you get really desperate, I'd just get a new Trek 7000. Nothing beats being able to bike. :D

chandltp 10-21-11 01:57 PM

Quote:

Originally Posted by hybridbkrdr (Post 13396446)
If you get really desperate, I'd just get a new Trek 7000. Nothing beats being able to bike. :D

I considered that, and had I known I would have had these problems, I would have considered it. I spent $240 on new wheels, cassette and crankset. For another $100 that's a new Trek 7000. Granted, if I buy new, it will be a different style bike, so I guess that doesn't hold.

I'm starting to wonder if they didn't put on wider cranks, since it's the inside of my knees that are bothering me.

Hopefully I'll be able to make it in this weekend or sometime next week when the weather is a bit nicer for a visit.

chandltp 10-21-11 01:59 PM

Quote:

Originally Posted by triumph.1 (Post 13395701)
if everything is the same except the new crank. Read the length on the inside of each arm. You may have been given longer crank arms than you had previously. I recently went from 175 down to 172.5 and that made a big difference in a good way for me. The 175's were a bit stressful on my old knees. If your shoes are the same the seat is the same there isn't much else that could cause a sudden difference.

Problem is I doubt it will be written on the old ones (that I don't have anyway, they were pressed together and toast).

I have noticed it's harder to spin (I start bouncing and I didn't used to), so maybe that did change.

Boy, you guys are giving me motivation to blow off home improvements tomorrow afternoon and go to the LBS.

work4bike 10-21-11 08:16 PM

When I first started doing squats I was told NOT to go below parallel (break parallel, e.g. http://www.youtube.com/watch?v=Iy7yS...eature=related), because it's bad for the knees. However, I later learned that you should break parallel or else you're not exercising completely.

If your crank arm is a little long I don't really see a problem, yes maybe your knee isn't use to it, but I see it as a weakness in the knee more than a problem with the bike. Much like when I started doing deep-bending squats it hurt my knees and I couldn't go all the way down, had to condition myself to do it, but now I have no knee issues.

I don't mean to down play the importance of correct bike fitting, but on the flip side it is not an exact measurement that must be maintained down to a few mm's. Maybe for the pros, but for us regular joes...well suffice it to say I don't really worry too much about exact geometry fitting when I change out my drivetrain, or even get a new bike.

Interesting read about crank length http://sheldonbrown.com/cranks.html

chandltp 10-22-11 05:44 PM

Well, I went to the bike shop and they said it should be identical, except the new BB was possibly 4mm wider. They don't see that would cause knee pain like I'm experiencing.

So next week I'm going to try to schedule an appointment with a physical therapist that specializes in sports injuries. He has the capability to record an analyze me on my bike on a trainer to figure out if I have some sort of bio-mechanical issue. Ideally, he might find the cause of my hip pain that regular medicine has been unable to resolve or diagnose.

deep_sky 10-22-11 08:26 PM

Quote:

Originally Posted by chandltp (Post 13400631)
Well, I went to the bike shop and they said it should be identical, except the new BB was possibly 4mm wider. They don't see that would cause knee pain like I'm experiencing.

Bet they haven't ever had a fit problem on the bike, either. There are some people, and I am one of them, where millimeters do indeed matter, and even 1-2mm makes a noticeable difference.

triumph.1 10-22-11 09:27 PM

Quote:

Originally Posted by deep_sky (Post 13401134)
There are some people, and I am one of them, where millimeters do indeed matter, and even 1-2mm makes a noticeable difference.

This for sure


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