Author Topic: Bike fit  (Read 6394 times)

321up

  • 59° N
Bike fit
« on: 24 January, 2015, 07:53:27 pm »
We finally got around to having a proper bike fit assessment.  Learn't a lot about ourselves that we did not know and found out what's wrong can be improved with our setup.  Most suprising is that we would both benefit from our right cranks being 5mm shorter. 

This is where we went and we are very pleased with the Pro-Fit service...

http://www.bicycles-by-design.co.uk/services/sizing-and-fitting

[edited due to poor choice of words]

Rhys W

  • I'm single, bilingual
    • Cardiff Ajax
Re: Bike fit
« Reply #1 on: 24 January, 2015, 09:47:36 pm »
The reasoning behind crank lengths based on leg length has been established for decades, it's just difficult to get decent cranks in anything except 170mm (and 172.5mm or 175mm). I'm pretty sure I'd be better off with 165mm cranks myself. One day I'll try it.

I'm very sceptical about these bike fitting services charging large amounts of money for what is basically common sense. I recently bought a bike, and the shop owner took a few measurements to determine which frame size I needed. When I went in to pick up the bike I asked him for a tape measure to check the saddle height. It was identical to my other bike, to the mm. The reason was, we both used the Hinault/Lemond formula to determine saddle height. Different bikes feel different though, and I felt low on the new one, and ended up raising the saddle by 3-4 mm.

LittleWheelsandBig

  • Whimsy Rider
Re: Bike fit
« Reply #2 on: 24 January, 2015, 09:50:51 pm »
There is remarkably little evidence relating leg length to optimum crank length. Individuals with the same leg dimensions (thigh and shin length) can have quite different optimum crank lengths, based on power output and heart rate.

HK runs 5mm different length cranks on some bikes and uses a 5mm shim under her cleat on others to compensate for a short leg, along with cycling-specific orthotics.
Wheel meet again, don't know where, don't know when...

zigzag

  • unfuckwithable
Re: Bike fit
« Reply #3 on: 24 January, 2015, 11:22:41 pm »
one online calculator suggested i should use 185mm cranks (what?!). i'm happy with my current 170mm ones thankyouverymuch. imo, there are many pseudoexperts applying pseudoscience in bike fitting business. some of them can be great if they truly listen to your needs/problems/pains. i've heard of people going to three different fitters and getting three different results for the same style of riding :D

Rhys W

  • I'm single, bilingual
    • Cardiff Ajax
Re: Bike fit
« Reply #4 on: 25 January, 2015, 08:34:28 am »
Of course there was that article in CTC magazine a few months when the writer went to 3 different bike fitting places... And came back with 3 different positions! And not by 2-3 mm either.

Re: Bike fit
« Reply #5 on: 25 January, 2015, 06:36:16 pm »
That was a good article. Position is important, and cycling clubs have given good advice for decades. However, I view the professionalisation of bike fit (under which the average cyclist is advised to spend £200 on a fitting) rather like the professionalisation of maintenance and many other things that we previously just got on with.

These things need thinking about, but are not that hard in normal circumstances. Professionals are there to help the talented get a small extra margin, and those with developing problems get advice before those become serious. Most of us will do very well as amateurs learning from our more experienced fellow-riders.

Especially when you realise that the professionals don't all come up with the same answer, so there isn't a single "right" to find.

321up

  • 59° N
Re: Bike fit
« Reply #6 on: 26 January, 2015, 09:59:25 am »
I've not seen the CTC article, sounds interesting.

I started riding with the CTC about 27 years ago, my first 200km Audax was 25 years ago, and I've been fitted for a few new bikes over that time.  So I've had lots of advice over the years and I thought my setup was about right.  However no one had noticed my legs were different lengths.  As soon as I tried the sizer cycle with the right crank 5mm shorter it felt better.  The cost of replacing both right hand cranks we bought with our last tandem will exceed the cost of the bike fit service, so in our case it would have saved us money to have had it done sooner. 

One of the things I liked about the bike fit we had was the sizer cycle allowed the reach to be adjusted as we rode.  So the reach was increased and decreased repeatedly until the most comfortable position was found - I think that this is a much better technique than trying different length stems on different rides.  In my case I've rarely changed the stem from the one I bought with the bike (i.e. I've stayed with the stem length that I chose when buying each bike).



C. is fairly tolerant of a variety of riding positions and favours what she is used to on each bike.  The sizer cycle allowed her to experience the effect of adjustments and the advice she was given was very helpful.

It remains to be seen if there will be any tangible benefit to our modified riding positions.  I hope that it will make longer rides a bit more comfortable, efficient, and help avoid injury as our mileage increases.

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Bike fit
« Reply #7 on: 26 January, 2015, 06:49:51 pm »
There is remarkably little evidence relating leg length to optimum crank length. Individuals with the same leg dimensions (thigh and shin length) can have quite different optimum crank lengths, based on power output and heart rate.

HK runs 5mm different length cranks on some bikes and uses a 5mm shim under her cleat on others to compensate for a short leg, along with cycling-specific orthotics.
I can't say I've seen anything to disagree with that!

But I did see some believable stuff about using MUCH shorter cranks; maybe 130mm regardless of leg length IIRC?  Didn't seem to get much purchase with the manufacturers ...
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

RichardH

  • All Time AUK 979 Pts
Re: Bike fit
« Reply #8 on: 28 January, 2015, 02:00:21 pm »
I used to ride with 170mm cranks, but in my 1st proper audax season I started getting knee pain after a 200km. Someone advised me to get some shorter cranks. So purchased a 165mm crankset, the knee pain completely disappeared.
A few years later I read an article on crank length, from this I worked out that I should have been using cranks slightly less then 160mm. So I scanned the secondhand market for a set of such cranks, once fitted they never felt good as my power was well down on the 165mm cranks. Strange that I could feel the difference going from 165-160mm but not from 165-170mm other than the knee pain on longer rides. You might laugh but they also made my arms ache more, probably tipped my balance point further forward. My saddle was already slammed back as far as possible.
Small frames have such a steep seatpost angle, I am now using 40mm set back posts to allow me to get a better weight distribution point. I wonder if the shorter cranks would work better now I'm sitting 20mm further back than in those days. Shame I sold them long ago.
4 x Wessex Sr. Crackpot 1998. PBP 1999.

Kim

  • Timelord
    • Fediverse
Re: Bike fit
« Reply #9 on: 28 January, 2015, 02:23:11 pm »
My take on crank length is that cranks that are too long are unambiguously Bad.  Assuming gearing and bike fit are adjusted accordingly, cranks that are too short are just less efficient, and the optimal shortness (measuring down from the point where they're not too long) is likely to be as much about riding style (which may vary between road bike, MTB, recumbent, etc) as leg length.

Re: Bike fit
« Reply #10 on: 28 January, 2015, 02:29:15 pm »
@321up.. Did they manage to couple the bike fitting up to a watt meter or something to catually measure increase/decrease in power output for various fits, or did they simply keep asking if this or that was better?

@ RichardH..When you had your 160mm cranks fitted, did you raise your h/bars to match the raised saddle position given by the shorter cranks? If you kept yourh/bars at their lower position for 170mm cranks, your body would be more forward leaning and therefore more weight/pressure on you arms.

I ask these questions as I'm constantly tinkering with me setup to try and find the most comfortable one for long distance riding. I also have fitted 160mm cranks to my audax bike and have 170mm cranks on my steel heavyweight bike. I can tell a difference between the crank lengths and yes suspect slightly less power from shorter cranks as I feel I have to put more effort in climbing with them but they feel they suit my shortish legs better somehow.

Re: Bike fit
« Reply #11 on: 28 January, 2015, 02:35:06 pm »
The first and only time that I have been measured for a bike fit was by Roberts Cycles when I had my Roughstuff tourer built in 2004.   When I got on the best I knew immediately that it was the best, most comfortable fit for a bike that I'd ever had.   The saddle had been wrongly set low as was established after the test around the block and a quick check with a tape measure back at Roberts.

Since then I have worked to reflect these measurements onto all of my machines and I have to say that my back ache which was once a permanent fixture and I was a martyr to has long since disappeared.     

velosam

  • '.....you used to be an apple on a stick.'
Re: Bike fit
« Reply #12 on: 28 January, 2015, 08:35:16 pm »
I am going to have to contemplate a fit, as I can't work out how to get ride of my RHS shoulder ache.

I have read all of Steve Hogg's stuff, Bike dynamics etc several times, but there is some basic wrong with my position.  The best I have got to is a dull ache.

RichardH

  • All Time AUK 979 Pts
Re: Bike fit
« Reply #13 on: 28 January, 2015, 08:41:08 pm »
Hi JohnR, I didn't change anything other than the crank lengths, but if I was going to try 160 cranks again I would raise the saddle by about 3mm & push it back say 3mm.
Last season I really suffered with my lower back, so have invested in a couple of 40mm setback seat posts. Now the saddle is 20mm further back & about 10mm lower. I have only done short rides of no more than 30 miles since changing the saddle position, back is less grumpy. Got to give it time before making any further adjustments. Seems to give me more endurance power on the turbo, but my cadence has suffered. Feel more balanced but knees are still in front of the center of the pedal spindle with the cranks in the horizontal.
My original position couldn't have been too bad as I managed to do 120,000 miles , but perhaps the accident I had 3 years ago has changed my requirements/tolerance.
4 x Wessex Sr. Crackpot 1998. PBP 1999.

Re: Bike fit
« Reply #14 on: 28 January, 2015, 09:11:57 pm »
Hi Richard.  What make are your 40mm seaports and where did you get them.

Re: Bike fit
« Reply #15 on: 29 January, 2015, 09:00:02 am »
Hi Richard, thanks for reply, interesting reading your setup changes.

I changed to 160mm cranks for a couple of reasons:
1 To alleviate toe overlap with front wheel on my Giant OCR.
2 To enable me to bring my knee rearward nearer KOPS.
3 To see if I needed shorter cranks.

My current setup I feel is nearly perfect except when I did the winter solstice, I was fine until the last bit from Old Ma's coffee shop where I started with pain in my hands (and backside!), presumably due to my weight being slightly too far forward resulting in too much weight on my hands. I cannot lift my hand off the bars without either falling forward or sitting more upright, so I probably need my saddle moving further back - as you have done.

RichardH

  • All Time AUK 979 Pts
Re: Bike fit
« Reply #16 on: 30 January, 2015, 01:45:51 am »
Hi freeflow, I found a couple of Nitto s84 seat posts secondhand on ebay, but 1 had to come from the states.
A company called Hub Job sell them new for £89   

http://hubjub.co.uk/index.php/store/seat-posts/nitto-s84-seatpost-detail

I see they are not 40mm but 37mm, must have measured them incorrectly.
They are a little on the heavy side.

I also have a Velo Orange Grand Cru post which has 30mm set back, but much lighter/cheaper

http://www.ebay.co.uk/itm/Velo-Orange-Grand-Cru-27-2mm-Alloy-Seat-Post-with-30-2mm-of-set-back-/201191013567?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item2ed7eb3cbf

JohnR I also have trouble with toe overlap due mainly to the fact that I have short wide feet, therefore have to use shoes 2 sizes larger. So I have to position the cleats way back on the shoe. 50mm of toe overlap, no problem until the cycle path gates.
When using shorter cranks my knees go more forward of KOPS unless I move the saddle back to compensate.

Be careful not to move the saddle back too far as this could cause lower backache. You need to be pedaling quite hard in order to lift your hands from the bars, a thing best done on the turbo. This is why when your legs start getting tired it puts more weight onto your arms. I tend to slow down more when my arms get tired.

This more rearward position is still early doors for me, but it feels good & more powerful. The 1st 200k of the season will tell me a lot. 
4 x Wessex Sr. Crackpot 1998. PBP 1999.

Re: Bike fit
« Reply #17 on: 30 January, 2015, 11:24:53 am »
Richard

Thanks for the update.  I'm aware of Nitto seatposts but unfortunately they only come in 27.2mm.  I have a velo orange seatpost but again this is 27.2 and my new frame needs 31.6.  I'm currently using an FSA sl-K which has 32 mm setback and have seen, but not investigated,

http://www.ebay.co.uk/itm/eXotic-Cross-Country-Road-Cobra-Carbon-Monocoque-Seatpost-31-6-300-mm-Seat-Post-/140715332255?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item20c349929f

Which are claimed to have a 40 mm setback (but what looks like a breakage prone rail clamp).

Re: Bike fit
« Reply #18 on: 30 January, 2015, 12:36:34 pm »
Richard

Thanks for the update.  I'm aware of Nitto seatposts but unfortunately they only come in 27.2mm.  I have a velo orange seatpost but again this is 27.2 and my new frame needs 31.6.  I'm currently using an FSA sl-K which has 32 mm setback and have seen, but not investigated,

http://www.ebay.co.uk/itm/eXotic-Cross-Country-Road-Cobra-Carbon-Monocoque-Seatpost-31-6-300-mm-Seat-Post-/140715332255?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item20c349929f

Which are claimed to have a 40 mm setback (but what looks like a breakage prone rail clamp).

You can buy a seat post shim for about a fiver. USE make some nice plastic ones, that will also help avoid electrolytic bonding of said post with farme (if materials are dissimilar)

Mike

zigzag

  • unfuckwithable
Re: Bike fit
« Reply #19 on: 30 January, 2015, 12:57:15 pm »
Richard

Thanks for the update.  I'm aware of Nitto seatposts but unfortunately they only come in 27.2mm.  I have a velo orange seatpost but again this is 27.2 and my new frame needs 31.6.  I'm currently using an FSA sl-K which has 32 mm setback and have seen, but not investigated,

http://www.ebay.co.uk/itm/eXotic-Cross-Country-Road-Cobra-Carbon-Monocoque-Seatpost-31-6-300-mm-Seat-Post-/140715332255?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item20c349929f

Which are claimed to have a 40 mm setback (but what looks like a breakage prone rail clamp).

another (more exciting) option is to sell a frame and get a new better fitting one. easier said than done though as majority of frames come with steep seat tubes, especially on smaller frames.

Re: Bike fit
« Reply #20 on: 30 January, 2015, 02:18:20 pm »
Quote
another (more exciting) option is to sell a frame and get a new better fitting one

Just done that.  New frame plus SL-K seatpost means I can get most saddles on the bike BUT not Brookes (except my Cambium), Still about 1-1.5 cm short.  I have a very nicely broken in Team Pro whose rails are still a little short for my position.  And my new frame has a 71 degree seat tube angle.  I think I'm just a weird shape.

zigzag

  • unfuckwithable
Re: Bike fit
« Reply #21 on: 30 January, 2015, 02:42:57 pm »
that is a big layback indeed! longer cranks and cleats slid right to the back may help, as long as that doesn't cause other issues.

Re: Bike fit
« Reply #22 on: 30 January, 2015, 04:02:54 pm »
Its the consequence of a bike fit that has proved very successful.  Resolved lots of problems I was having with numb (for several days)  fingers in my left hand, hot foot in my left foot, left sit bone, and neck and shoulder ache.  I can now do 300k Audax in relative comfort so I'm reluctant to change.  Currently if you do the kops measurement I'm about 0.75 inches behind the spindle with my cleats at the furthest back position they will go.  If I use a shim (which I'm reluctant to do) then I could go for

http://www.bike-discount.de/en/buy/humpert-ergotec-futura-seatpost-27.2mm-222225

except I'm about 20 kg over the weight limit. 

Also, my weird shape fits into 5' 11".

GrahamG

  • Babies bugger bicycling
Re: Bike fit
« Reply #23 on: 30 January, 2015, 05:30:59 pm »
Quote
another (more exciting) option is to sell a frame and get a new better fitting one

Just done that.  New frame plus SL-K seatpost means I can get most saddles on the bike BUT not Brookes (except my Cambium), Still about 1-1.5 cm short.  I have a very nicely broken in Team Pro whose rails are still a little short for my position.  And my new frame has a 71 degree seat tube angle.  I think I'm just a weird shape.

Nah, Brooks have just neglected to actually re-design their saddles for modern bikes, you're buying saddles with rails designed for 100 year old slack-as-hell-seat-angle frames.
Brummie in exile (may it forever be so)

321up

  • 59° N
Re: Bike fit
« Reply #24 on: 04 November, 2015, 10:11:13 am »
Update...

Moving our saddles further back has definitely improved our comfort.  It seems that in the past I unwittingly compensated for the saddle being too far forward by having the saddle too high and sitting too far back on the saddle.  I wish I'd had a proper bike fit years ago.  I'm not sure if we've found our perfect bike fit yet, but its definitely a big improvement and every bike I've adjusted thus far has become more comfortable.  It's difficult finding and expensive buying non standard parts though.  I've fitted 35mm offset Specialized Alias Alloy Seatposts to our Dolan Tandem & my old Thorn Club Tour but they are not available in the smaller diameters needed on C's bicycles.  Affordable new bikes and off the shelf frames (Audax/cyclocross/touring) with seat tubes <72 degrees seem to be non existent.

I'm interested in having another pro bike fit to refine our riding positions and verify I've got our bike setups right.  We spoke to someone on a ride who described having his riding position analysed by a computer system with a video camera - who does that?  What bike fit services would you recommend?