NeoteriX

I’m getting knee pain when I ride, and at first I figured it was some of the usual suspects--seat height too low, seat not properly adjusted fore/aft. But even after making sure the seat was high enough, doing the plumb line/knee test, and even getting the pedal extending “kneesavers,” I’m still getting some knee pain. I love my Tern Verge x10 folding bike (and it fits in my New York apartment great), and I’m just trying to figure out what the problem is here (whether it’s me, whether it’s the bike, whatever) so I can keep riding.

Some people here have at least suspected that some people’s knee pain can be isolated to just folding bikes and their geometry (versus regular sized road bikes): https://www.bikeforums.net/showthread...bike-any-ideas

Either way, I don’t want to necessarily take it back to my shop; part of the issue here is that folding bikes largely don’t have the same options for fit and customization, so their staff isn’t necessarily skilled in assessing such things. I also would prefer not to (if I can avoid it) going to some road bike shop that is skilled in fit issues just for them to jump to the conclusion that folding bikes are rubbish and what I need is another expensive custom-fitted road bike when it’s going to be big and cumbersome to deal with in the city and my apartment.

The other thing is, my problem might lie at some unknown intersection of the standard bike fitting/geometry stuff and some more esoteric geometry issue: ever since I could walk, my knees have been a little weirdly aligned so that my feet splay outwards quite a bit, especially when bent. A bike shop may only be able to diagnose the former regular bike fit issue, a sports doctor without bike specific knowledge may only be able to diagnose the latter issue in a limited, non-biking related way. If it's just a "I have messed up knees and maybe biking isn't for me" issue, this would be useful to know before dropping another two grand on a new custom road bike or a fitted Bike Friday bike.

Anyway, I know this isn’t a place for medical advice, but I just wanted to see if anyone can spot some basic issues I might be overlooking before I had to go with the expensive race bike shop route or sports doctor route (or give up biking altogether).

There’s a high speed video of me biking as well as screencaps showing that I think everything looks ok, I can't identify any of the basic issues other than maybe my foot being angled too much (seat too high?). It feels good biking with my feet like that though, and feels most powerful at this height ("If it had been too low before, your bike will feel lighter and faster with the new riding position.")

Video:

Screencaps:

fietsbob

Do you have a road bike that does not have the issues you are noticing?

Saddle setback, at its base, is a measurement, from a Plumb line through the BB axis,
to where your butt contacts the saddle can be measured.

and compared to the Regular bike that is fine..

Old guy, I deal best with things in front of me not on videos.

maybe you are just turning too high a gear in quest of 'a better Work-out'.. IDK.

NeoteriX

Unfortunately, I have no other basis for comparison--I just got into biking within the past year, and given the whole small apartment/city life thing, went straight for a folding bike. It fits my life perfectly, I just hope that I can get this knee thing sorted out.

Maybe there's a too high gear thing, but how far can one really compensate with a lower gear and higher cadence? My cadence can really only get as high as 110ish on my trainer without my butt bouncing around... I can't imagine getting much higher than that spinning.

Thanks for taking a look!

fietsbob

Best would be a Sports Orthopedic, medical specialist, ergonomics analysis..
of course they need familiarity with cycling..

you done the Knee over pedal axis test?

crank at 3; &9:00, ie, level, plumb line from front of knee cap, front foot, falling through pedal axis.

part of a knowing fit by referring to numbers..

Thigh length changes , individuals are.. different. , ..

crank length and pushing the seat back & forth on its rails just part of the adjustments..

[I have too slow a computer to see the vid, anyhow.. ]

badmother

Hmm, can`t help thinking you may have started out too hard, expecting too much from your knees.
https://www.tri247.com/article_2670.html

https://www.bikefitting.com/English/S...roduction.aspx

https://www.peterwhitecycles.com/fitting.htm

https://sheldonbrown.com/frame-sizing.html

https://www.rivbike.com/kb_results.asp?cat=23

The film made me think your saddle is high, too high.

I support fietsbobs suggestion on finding somebody that can "read" your body that ia also into cycling. they must be out there. Maybe as you say stay away from peopel who would only try to sell you a new bike.

badmother

Here they actually talk about knee and foot angle (in the begining of the film) and about correcting it. This is film number two, there should ba a number 1 and maybe more.

https://www.youtube.com/watch?v=umUSVWf5604

Several others also as you can see. Much more info than you need and confusing, but I think in your case it may be worth it reading several peopels opinion, watch some films and then go back to what makes sense for you.

dynaryder

Yeah,from what I could tell from the video,it looks a little high. Also looks like you could move the saddle forward a tad. You want your kneecap over the pedal spindle when the crank is straight forward/parallel to the ground.

Where in your knee does it hurt? Are you using platform or clipless pedals?

NeoteriX

Hey all, thanks for the feedback!

I'll check out the videos and articles.

To answer a few questions:

I'm using platforms, but with power grips. The Power grips are loose enough so that my feet can splay out a bit and aren't held straight. They are a fairly new addition though, and I was getting knee pain without them just on platforms. The knee hurts generally below the kneecaps and around that area.

As for overdoing it at first, that was definitely true--when I started out on the bike, the seat was way way way too low and I hurt my knees like that on the very first day, but as I rode it, I kept adjusting it upwards for a week or two at a time until I got to the height seen on the video. The thing is, I didn't ride for December and part of January, and figured that would be a good break, but when I started up doing intervals again on the trainer, I'm definitely feeling weakness and some pain.

I've already moved the seatpost down a few notches and will see how that feels.

Regarding the plumb line and saddle--in the screencap images I drew lines:
https://www.bikeforums.net/attachment...1&d=1361130679
https://www.bikeforums.net/attachment...3&d=1361130685
To me that looks pretty good, but maybe I'm not seeing it right--what do you all think?

smallwheeler

i would recommend you go see or talk to David Lam. he is the most knowledgeable person regarding folding bikes and fit in new york city. call him and see if he can help you. at very least, he will be able to point you in the right direction. although, dont be too surprised if you have the urge to trade in the tern for a bike friday..

https://www.bfold.com/

https://plus.google.com/108183351053...79/about?hl=en

NeoteriX

Haha this is the very bike shop I bought my Tern from. They're a great set of guys, I guess it wrongly never occurred to me to ask about fit. All the videos I've seen on the internet regarding fit are in big stores with computers, cameras, angle measurement devices and such and I guess that's what my expectation was for the kind of experience I'd need to have--the bfold shop is a gadget/bicycle lover's dream with bikes, tools, and stuff everywhere, but crammed into a small modest basement space; I guess a kinda different image than what I had in mind from a fitting perspective.

I'll go ahead and drop by sometime to ask. Thanks!

a.

smallwheeler

well, yeah. he's not going to put you on some high tech fit machine. but, he can help, i'm sure of it. particularly since you are already his customer! dont wait too long to do it..

test ride a Bike Friday while your'e in there.

Folding-Bikes

Looks like you are sitting a little too far back, this shouldn't affect your knees but it will affect your handling.


If you go to Bfold test ride the Reach while you are at it too, its more of a bike that folds than a folding bike.




Juan

BassNotBass

In all honesty to me it looks like your seat is a little too low for your pedaling technique. Your ankle seems to be pretty rigid with toes pointing downwards most of the time so at the bottom of your stroke your leg doesn't extend as much as I think it should. Alternatively at the upper stroke your knee is bent more than I think it should be. Not to say your technique is improper, I'm just suggesting that because of it, your knees seem to be subjected to the same conditions as if your seat were too low which is usually a cause of knee stress/pain.

What length is your inseam and what length cranks do you have on the Verge? Also what is your usual pedaling cadence?

pacificcyclist

Do you have any prior sports related injuries? Hips and lower back? Any chronic pain on the lower back area near the pelvic bone and do you sit on the chair in the office a lot? Is your left knee more painful compared to the right?

NeoteriX

The seat is in fact all the way back, but I put it there in the effort to get that knee-plumb-line test to line up correctly. At least I think if you see in the photos when you click to expand them, I think it's lining up properly.

Also I think the Pacific Cycles IF-Reach is an awesome bike... if they came out with an IF lightweight version with drops, I would throw my money at it.

Interesting observation... I'll try experimenting with a higher seat, although if my memory serves correct, at seat heights higher than the video it begins to feel like I'm reaching. I'll try it though.

My inseam is roughly 32-33" (which is my pant size, I haven't actually measured with tape). Josh Hon from Tern says the stock crank is 170mm. I've been trying to increase my cadence in order to reduce knee pressure, but I'd say that on the road my typical cadence is probably around 80ish rpms.

No, I haven't had any major sports related injuries, but I think in prior years from running I might have had some knee weakness and foot plantar fasciitis. Hips and lower back are ok as far as I know, sometimes if I'm at the computer too long I'll feel a little soreness but nothing huge. Yeah I sit in the office a lot. And, I get knee pain in both knees--though it varies which feels worse; when I've done a lot of stop and go biking for example, my right knee can feel more sore since it's the pedal I mash on to get the bike going. That said, sometimes the left knee feels worse for whatever reason too. Ever since I started noticing knee pain, I've tried icing both after all my rides.

1nterceptor

From watching your leg extension in the video, it looks like you can raise the seat post a bit more.
Assuming of course you're not at the max limit yet. 80 RPM is a bit low, try 90 and up:

https://www.youtube.com/watch?v=Jea4lv48bDQ

pacificcyclist

Runners Knee or Chondromalacia Pattelae (around the knee cap) is a known major sports related injury related to imbalances of the muscles groups (quad and hamstring). Typically, physical therapy will help restore muscle balances around the knee cap around and core strength exercises and stretches to lengthen the quads and hamstrings since you sit a lot. Sitting a lot is a major contributor to shortening of the ligaments and tendons on the hamstring and quad, so when you start running or biking, tightness on the hip area will usually result in your moving the hip to go forward by collapsing on the pelvis (tilting side to side). I saw in the video that you do have an abnormally high movement in this area. This means when you pedal, your knees will keep collapsing and this joint is trying to overcompensate a motion that it should not have to do if your hips are looser, hamstring and quad muscles are working properly. This can result with what is called Runners Knee. Since you have had it while running, you have yet to address this issue, so even if you start biking or even spending more money on bike fit, you will still have muscle group imbalance. Perhaps a well fitted bike can lessen the pain, but as you bike longer, the pain will eventually come back.

I would highly suggest that you see a Sports physio and have him or her evaluate your posture and riding style. Keep in mind that most people pronate as they walk so the knee will collapse somewhat inwards. Usually if you have a strong core, this collapse is mitigated by pelvis stability due to the use of the Transversus Abdominus that helps stabilizes it. The end result is that, the core keeps a level pelvis and the legs go straight down like a pair of pistons. Same with runners with strong core that the pelvis remains relatively level as they run slow or fast. Despite what you think, shock from the road does not cause knee pain and usually you have running shoes with materials that absorb the shock really well.

Hope this helps.