Author Topic: lateral tracking of the patella - talk to me about knees, cranks and PE  (Read 14153 times)

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #25 on: 12 October, 2015, 07:27:58 pm »
buy the exact same ones in a different length (model number will be on them somewhere, but they might not be easily available any more, depending on how old they are

(click to show/hide)

The tourer is - I was told - a 2012 Dawes Galaxy. *googles* The catalogue says the chainwheel is a "Shimano 48/36/26"  So not overly helpful, perhaps.


The chap I bought the hybrid off also gave me a printout of a web page with what he said was the spec: it says "Chainset: Shimano FC-TX 71 28/38/48 tooth chainrings".
*googles*
This looks convincing: https://www.paul-lange.de/support/shimano/explosionszeichnungen_archiv/FC/FC-TX71.PDF and has spare part numbers too ...but my Google-fu stops there.

From the diagram, though, it does look like I'll have to buy a whole crankset.
From the illustration of part 2, can I deduce that it's a square taper? Are there variants within that, or will any square taper fit the middle bit? (Is that what the bottom bracket is, or is that something different?)



Kim

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #26 on: 12 October, 2015, 08:27:12 pm »
It's academic, as they probably don't make them in less than 170mm anyway.  Higher-end Shimano stuff is available down to 165.

Yes, that's square taper.

Square taper comes in JIS (the one that everyone uses) and ISO (what Brompton used to use, and undoubtedly appears on random exotica) variants.  You can, I believe, mismatch them successfully, with a poorly defined effect on chainline.

Other than that, it's about the length of the BB spindle required to achieve the correct chainline, but since it's already set up for a triple, it's probably not that critical.  (Ultimately limiting factors on a non-folding bike being the chainring fouling the chainstay, or the front mech not being able to reach the big ring.)

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #27 on: 12 October, 2015, 08:50:46 pm »
Square taper comes in JIS (the one that everyone uses) and ISO (what Brompton used to use, and undoubtedly appears on random exotica) variants.  You can, I believe, mismatch them successfully, with a poorly defined effect on chainline.
Campag are ISO, so quite a lot of exotica.

If you put ISO cranks on a JIS BB, the cranks don't go on as far as is ideal, so the chainline is a bit further out. It pays to do the crank bolt up tighter than normal.
If you put JIS cranks on an ISO BB, the cranks go on further than normal, with the result that the crank bolt may bottom out on the end of the axle before the crank is properly tight. If that happens, you can wreck the crank in a relatively short ride.

Kim

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #28 on: 12 October, 2015, 08:57:55 pm »
Campag are ISO, so quite a lot of exotica.

Ah, I didn't know that.

I admit that I don't pay much attention to Campag, as incompatible high-end road groupsets are, to me, only marginally more useful than a chocolate teapot.  Nikki can safely ignore them for not entirely dissimilar reasons.

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #29 on: 13 October, 2015, 07:33:16 am »
My opinion on this is you should firstly rest, then perform restricted movement exercises until the tendons and cartilages have developed to match the strength of your muscles.

Riding a bicycle is an excellent ‘restricted movement’ exercise for the knees, but should not be taken to excess. Most gymnasium exercise ergometers won’t simulate steep hills. Some are a set gear ( @ 80” ) and the resistance mechanism simulates a gradient, up to approx. 5%. They are engineered like this so people new to cycling don’t go crazy and wreck their knees.

To be quite brutal, and for folks with youngsters, start cycling soon after you have learned to walk. Start gently and work up over fifteen years to where no hill is a problem.  :thumbsup:

simonp

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #30 on: 13 October, 2015, 09:30:00 am »
I used to have lots of knee issues and was told the don't push a big gear thing.

These days I ride almost exclusively fixed and have far fewer knee issues. What else has changed:

 - I think I got my position dialled in
 - I stopped using Brooks saddles. B17 was too wide causing problems. The sagging in the wet also changes the position over time.
 - I've switched to 165mm cranks on my fixed bikes
 - Strength training

I'm not completely free of it but things are massively improved.

Kim

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #31 on: 13 October, 2015, 12:38:37 pm »
Yeah, I don't think the "don't push a big gear" rule is, well, fixed.  I'm certainly able to push much higher gears (on uprights[1]) without injury than I ever used to be.

But it seems like good advice for people who haven't developed strong cycling muscles, and certainly if the ergonomics aren't quite right.


[1] I maintain that mashing on recumbents is still a terrible idea.  Even if you don't fall over, being able to use the full strength of your legs against the seat is bad news for your drivetrain, as much as your knees.

Marco Stefano

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #32 on: 13 October, 2015, 08:47:08 pm »
Sorry to hear about your pains, Nikki.

This sounds similar to something that seems to occur in rowing, chondromalacia patella, which I believe is due to muscle imbalance pulling the patella over to one side so it rubs underneath. In rowing, depending on how boats are rigged the last set of muscles that straighten the leg get less work to do than the previous 3 sets, or rather the legs cannot straighten completely, i.e. it is an ergonomic issue. Throw in loads of miles on the water and there you go; I have had it mildly myself.

Various exercises to reintroduce muscle balance (like the one in the picture upthread straightening the leg under leg weight alone) seem to work for rowers, but not sure about cycling-specific problems. Hope you can get sorted out soon.

hellymedic

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #33 on: 13 October, 2015, 09:12:38 pm »
I had patello-femoral maltracking problems about 30 years ago (enough to cause an effusion). As I was working in orthopaedics at the time I did the static quads exercises the boss was foisting on his victims prescribing for his patients.
I had little trouble after this though I'm pretty knock-kneed.

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #34 on: 13 October, 2015, 10:20:15 pm »
I popped in to Kim's Engineering Works this evening, where we proved we1 could get the cranks off the hybrid ...and then temporarily put some shorter ones on just because we2 could.

One of my aims when I started cycling was to lose enough weight that I wasn't constantly hitting thighs against belly on each turn of the pedals. Shortening the cranks may get me there faster, but I'm not sure it's a metric of weight-loss the consultant will accept!  :facepalm:

After a quick circuit around the adjacent streets, we put the bike on the turbo and experimented with saddle height and knees. Turns out the way to focus Kim's attention on something is to put electrical tape on it  ;)

It seems my left knee does flick out a bit towards the bottom of the stroke, in a way consistent with our amateur understanding of what a weak VMO muscle might cause. With concentration/contraction I could minimise the effect, but I'm a long way off being able to do that for any useful length of time.

My right knee, however, seems to be a bit figure-of-eighty and have a tendency to sometimes swing out towards the top of the stroke. Hips suspected to be a contributing factor there. Will quiz the physio on Thursday.

Thanks for your well-wishes, Marco Stefano. From a quick Google chondromalacia patella does sound to be at least in a similar ball-park to what's going on with me. There seem to be several overlapping terms. So many nuances in the ways knees can go wrong!

Static quadding as I type... *determined face*



[1] Kim
[2] Kim3
[3] Thanks Kim!

simonp

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #35 on: 13 October, 2015, 11:27:09 pm »
I've done those drills. At relatively easy loads my knees track very well these days. Under heavier loads not so much as I found out with this morning's force intervals.

If there's an imbalance of the muscles around the hip then looking at your knee might not be sufficient and physio might well be helpful.


Cudzoziemiec

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #37 on: 15 October, 2015, 11:19:11 am »
In addition to the shorter cranks, ISTR a thread quite some time ago where you were asking about a shorter stem or bars with less reach. Putting the two together (assuming it was the same bike) might suggest the whole bike is too large for you. Could be that stretching to fit an oversized bike exacerbates pre-existing muscular-skeletal issues? Though of course in that case the underlying problem would still be there whatever bike you rode.
Riding a concrete path through the nebulous and chaotic future.

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #38 on: 15 October, 2015, 01:18:43 pm »
frame size has *nothing* to do with crank size
<i>Marmite slave</i>

hellymedic

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #39 on: 15 October, 2015, 01:25:18 pm »
Many frames are designed for men, who often have longer reach for a given leg length. A woman might wish to address this by choosing a shorter stem.
Shorter top tubes can risk foot/front wheel interactions.

Kim

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #40 on: 15 October, 2015, 02:51:27 pm »
It wasn't the same bike anyway.  The reach issue was a result of those weird curly handlebars on nikki's Galaxy, which isn't getting a lot of use because knees.


frame size has *nothing* to do with crank size

Because, in classic Bill Gates style, 170mm should be enough for anyone.   >:(

I'm all for customisation in the interests of a better fit, but far too many small bikes are fitted with 170mm cranks by default by lazy manufacturers.  I expect the same applies to big bikes too, but that's much less of a problem.  People are used to swapping stems to fit, but cranks tend to be overlooked.

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #41 on: 15 October, 2015, 05:36:46 pm »

It's cartilage damage, I think, rather than ligaments - MRI appointment early next month to find out...
I have learned a lot about protein over the last couple of months as part of the diet change, though. I'm sure it would have been quite useful to have been taught this stuff at school!  ::-)

In addition to the shorter cranks, ISTR a thread quite some time ago where you were asking about a shorter stem or bars with less reach. Putting the two together (assuming it was the same bike) might suggest the whole bike is too large for you. Could be that stretching to fit an oversized bike exacerbates pre-existing muscular-skeletal issues? Though of course in that case the underlying problem would still be there whatever bike you rode.

That was Project Handlebar on the Galaxy, and I mentioned feeling a bit achey on the Wiltshire tour, too. It's not hugely different in size or relative placement of end of stem or saddle etc compared to the hybrid, which is to say, yes, it's not outside the realms of possibility that they're both too big.

The Galaxy is a 43cm frame. Maybe Eldest Cub can swap me for his Islabike when he's done with it...
I'm not sure how far off my feet are from the wheel, but certainly I'd be worried about shorter-top-tube-induced thigh and bar end lever interactions. Too many bruises already!

I think it was the extra few inches of stretch to get to the hoods/levers that I was feeling in Wiltshire, what proportion of that was because I'm no longer used to long days in the saddle, I don't know.



Today was a double physio day: the 3rd session with the 3rd physio for the knee, and the first you've-been-refered-to-us-let's-have-a-look session about last year's torn ankle ligaments on t'other leg.

Knee physio coped well with my list of questions. Might get to try taping at some point as a fall-back for when I know I'll be working the knee hard. He did pick up a leg length difference of a few mm (I stressed to him that this was the sort of accuracy I needed), and he says it'd be silly to try and avoid hills. They've just had their staff development training session on patellar femoral pain, though and he's urged me to go back to doing the knee dips and squats type exercises: open chain / closed chain controversy, apparently. Pain has gone up in the last week (since stopping them), as has knee popping and having to encourage kneecap back into position, so will do so cautiously.

Ankle physio said that cycling is a Good Thing and that I should be looking to increase the loading and push harder with the exercise.

Love a bit of contradictory instructions from medical professionals.
Sorry, did I say "love"? I meant it's horrible.

*grump*


Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #42 on: 15 October, 2015, 05:39:51 pm »
Oh, and it'll be six weeks before Spa Cycles get any more of http://www.spacycles.co.uk/products.php?plid=m2b0s109p2000 in in the 160mm flavour.

barakta

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #43 on: 15 October, 2015, 05:50:07 pm »
Love a bit of contradictory instructions from medical professionals.
Sorry, did I say "love"? I meant it's horrible.

*grump*

BTDT a lot. Then it comes down to you trying to interpret a load of medical gubbins which you know you can't possibly really grok and take the "best guess" approach, or decide who you feel gave you the best examination and responded best to you as a patient/client. 

I find I am often in the position where even the best bods are hmmming at me in that "well what do you think" kinda way and it ends up being a dialogue where we have to decide between us what to try, sometimes "pick one" and then evaluate etc.  I think you're into insisting on senior physios territory "I have had SO much conflicting advice, I need to know I can trust the experience of whoever I have" which isn't guaranteed but cuts out those doing it by numbers in their earlier years. 

Hope you manage to navigate a path through which works and doesn't cause more damage.

simonp

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #44 on: 15 October, 2015, 05:51:40 pm »
Swimming was useful for me. I found breast stroke kick not so good for my knee as front crawl. If you find either kick problematic, then you could use a pull buoy.

Cudzoziemiec

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #45 on: 15 October, 2015, 06:03:26 pm »
Just remembered I used to have a book called Knee Health, now on the YACF Lending Library.
https://yacf.co.uk/forum/index.php?topic=31979.0
Probably your particular problem is a bit beyond it (several years since I had it so can't remember) but could be worth a read, particularly as no one seems to be reading it now.
Riding a concrete path through the nebulous and chaotic future.

Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #46 on: 16 October, 2015, 02:39:09 pm »
Oh, and it'll be six weeks before Spa Cycles get any more of http://www.spacycles.co.uk/products.php?plid=m2b0s109p2000 in in the 160mm flavour.
The Stronglight Impact is also a version of the Sugino XD2 and is pretty much the same, and is available in 160 mm. It depends on whether the extra £24 is more important than the extra 6 weeks or not.
The 6 weeks will likely be subject to change.

Kim

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #47 on: 16 October, 2015, 02:49:38 pm »
Oh, and it'll be six weeks before Spa Cycles get any more of http://www.spacycles.co.uk/products.php?plid=m2b0s109p2000 in in the 160mm flavour.
The Stronglight Impact is also a version of the Sugino XD2 and is pretty much the same, and is available in 160 mm. It depends on whether the extra £24 is more important than the extra 6 weeks or not.

Good spot, and the extra £24 might be worth it for the better selection of chainring sizes (bearing in mind that you'll want to drop the ratio by a couple of teeth to compensate for the shorter cranks[1]).  I reckon 46/36/26 is a good match for a 160mm crank and a 11-34 cassette on a load-carrying bike.  46/34/24 might be a more knee-friendly option.


[1] Gear inches become useless at this point, and you have to calculate in gain ratios.

tonycollinet

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #48 on: 16 October, 2015, 06:19:58 pm »
Knee savers seem to have solved my (minor) knee pain.

http://www.kneesaver.net/

Available at SJS
http://www.sjscycles.co.uk/kneesavers-pedal-extenders-prod14725/

No idea if they'd help for you of course.

Kim

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Re: lateral tracking of the patella - talk to me about knees, cranks and PE
« Reply #49 on: 16 October, 2015, 08:59:18 pm »
Knee savers seem to have solved my (minor) knee pain.

Probably only going to make a difference if you're already using clipless.  I've got a pair of 20mm ones somewhere if nikki would like to try them.