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 Post subject: 165mm cranks
PostPosted: Mon Jan 23, 2017 11:30 am 
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Joined: Mon Jun 23, 2014 10:30 pm
Posts: 175
Little bit of advise requested from venerable forumites.. I am short lad (old man) with flexible hips and hams, my recent bike fit concluded what I've always suspected I had to do at some point.. and get smaller cranks.. currently running 170mm FC-9000 (DA) crankset.
So the obvious choice is to just get a set of 165mm FC-9000 cranks right..? except the £400/$500 outlay is a bit of a hurdle, but it's okay I can sell my old crankset and a carbon stem to cover some/most of it..

Or do I ignore the obvious.. take the opportunity to swap to another crankset (keeping all the other Di2 groupset parts?)
OR should I hold out for the new 9100 crankset, it should fit and work okay and it's a few grams lighter, but it's a couple of hundred more than I can really afford at the moment..

Or am I missing somewhere where I can just buy the right and left crank arms (without the cogs and fittings) for less than the price of a whole crankset.. this would make my decision easier?

All I know is I need 165mm cranks... I need some ratification of my thought process here so I don't miss an opportunity or make a bad decision.


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 Post subject: 165mm cranks
Posted: Mon Jan 23, 2017 11:30 am 


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 12:00 pm 
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Joined: Wed Apr 25, 2007 10:23 am
Posts: 1275
Location: Pack filler
If I were you i'd look for a pair of tiagra/ 105 level 165's and try them before shelling out big money on something that may or may not make any difference.

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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 12:04 pm 
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Joined: Wed Mar 05, 2014 9:20 pm
Posts: 100
yeah try em first,


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 12:15 pm 
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Joined: Fri May 25, 2007 6:43 pm
Posts: 3308
I'll be doing the same in the spring. New groupset came with 172.5mm (no 170 in stock) thought i'd be ok with that. Um. No.

Mild knee pain, some hip pain. So i'll be going the other way down to 167.5 or 165. If i was that marginal at 170 i might see some benefits to 165s. (even if it's only comfort, i can live with that.) I'll be starting with 105 or tiagra though........... (then if it works, i'll stick them on another bike and get some Ultegra or D-A for the nice bike)

Strangely i have no issue with 175s on the CX bike or the MTBs.


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 12:17 pm 
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Joined: Fri May 25, 2007 6:43 pm
Posts: 3308
And you usually find that buying a chainset piecemeal will cost you at least 30% more than just buying the whole thing complete.

Last i looked a set of rings was about £80. Then a pair of arms, near enough £120. You could pick up a complete chainset for ~£140.


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 1:12 pm 
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Joined: Wed Mar 05, 2014 9:20 pm
Posts: 100
http://www.ebay.co.uk/itm/Shimano-Tiagr ... 84-uCJZGqg


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 1:30 pm 
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Joined: Mon Jun 23, 2014 10:30 pm
Posts: 175
I didn't want to step down the range to Tiagra.
And I do 'need' the cranks the science of measurements confirms it... currently even in an optimised position there's a slight over extension at the bottom of the pedal stroke and I'm squashing my guts/diaphragm at the top of the stroke this = shorter crank requirement for a little legged short arse like me.
Attachment:
pete_angel.png
pete_angel.png [ 36.22 KiB | Viewed 1461 times ]


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 1:56 pm 
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Posts: 1275
Location: Pack filler
There is no "science of measurement", it is based on 1 persons opinion of what either a computer spits out at him, or what they think might work for you based on their previous experience.

What we are saying is, don't throw lots of money for something that is not a guaranteed success at whatever you think its going to change.
The main reason people go shorter is range of motion injuries, or for aero reasons when tt'ing.
If you change to a shorter crank length a lot of other things might need to be altered too to compensate. Its not just banging a shorter one on and away we go...

Personally I think judging from that pic, there is more that needs to be done with your basic set up, but like your fit, it is just another opinion.

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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 2:19 pm 
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Joined: Tue May 03, 2011 6:36 pm
Posts: 417
Location: France
I have a new FC-7900 53/39 I'm not going to use, PM me if interested.


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 4:14 pm 
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Joined: Sat May 15, 2010 2:01 pm
Posts: 245
Rotor do 165mm cranks.


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 4:19 pm 
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Joined: Mon Jun 23, 2014 10:30 pm
Posts: 175
jekyll man wrote:
There is no "science of measurement", it is based on 1 persons opinion of what either a computer spits out at him, or what they think might work for you based on their previous experience.

Personally I think judging from that pic, there is more that needs to be done with your basic set up, but like your fit, it is just another opinion.


It was a tongue in cheek comment. I've always felt that my knee crushing my diaphram might be helped by a shorter crank. The bike fitter measuring me after agreed.

I would be interested in your input/opinion regarding the setup based on the above.


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 4:52 pm 
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Joined: Tue Apr 18, 2006 3:03 am
Posts: 2666
Location: Islip, NY
peted76 wrote:
I didn't want to step down the range to Tiagra.
And I do 'need' the cranks the science of measurements confirms it... currently even in an optimised position there's a slight over extension at the bottom of the pedal stroke and I'm squashing my guts/diaphragm at the top of the stroke this = shorter crank requirement for a little legged short arse like me.
Attachment:
pete_angel.png



Just a quick observation. Looks like you could benefit from a flatter back by rotating your hips forward. That would give you some more real estate to work with.

I say that not knowing any of your fitness/flexibility/history so take it for what it's worth.


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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 10:04 pm 
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Joined: Tue Jan 28, 2014 6:52 pm
Posts: 1518
Quote:
It was a tongue in cheek comment. I've always felt that my knee crushing my diaphram might be helped by a shorter crank.


I felt that going from 175s to 170s. I liked it. I raised my saddled 5mms and kept my stem where it was so I ended up a little lower and more aero. The only thing I needed after was a 29 on the rear instead of the 27 I was using because with 170s I needed a little more spin on climbs.

I don't think you can go wrong. You can adapt to 165s even if they don't provide a magic transformation.

Another thing that might help is doing 10 minutes of stretching/yoga before and after every ride. That helps me immensely with on-bike comfort.

To help with the budget, you might check ebay for a used set in nice shape.

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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 11:17 pm 
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Joined: Wed Dec 30, 2015 12:41 am
Posts: 278
You know this is weightweenies,

Check your frame's BB type first. If it is BSA, PF86 or BBright then stick with Shimano as you desired.

However, if it is PF30 or BB30 then get rid of the adapter and use Sram RED BB30 crankset.
Sram's BB30 offering are more than 50 grams lighter than their GXP counterpart (which weight similar to Shimano 9100 series). And get rid of adapter BB to use native BB30 bearings (or PF30 module) will save another chunk of weight.

Then down the road when the ring worn down, replace it with Praxis Buzz chainring will save another 30-40 grams.
Light weight power meter is still an option via Stages Carbon left arm power meter (probably is the lightest power meter available since 4iii doesn't offer carbon arm).

It shift great, stiff, light and less expensive in real online market like ebay,etc. (not MSRP). Don't let fashion police stop you from crossing brands!


Last edited by Hexsense on Mon Jan 23, 2017 11:21 pm, edited 1 time in total.

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 Post subject: Re: 165mm cranks
PostPosted: Mon Jan 23, 2017 11:20 pm 
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Joined: Mon Jul 26, 2004 1:06 pm
Posts: 1094
The simple answer first. If buying new, buy an FC-9000 complete crankset (including rings). The rings are expensive to replace, relatively cheap when bought as a complete crankset. If buying used then buy whatever you can find. 165mm are hard to find as most people buy them for a reason and don't get rid of them.

I wouldn't hold out for FC-9100. Time, cost, and then your groupset isn't 'complete'.
I wouldn't go another option as Shimano chainrings just work the best...and keep the groupset complete. Call me boring.

As for your fit. Everyone will have an opinion. There is no exact science. Every fit involves a lot of subjective information and decision making, the numbers are just a tool. You have to put some faith in your fitter and give it a go. Then go back with some feedback so they can dial it in more based on that information.

You could definitely drop the nose of your saddle a bit, or slide your saddle back a bit so you sit on a narrower part of the saddle. Both of those things will roll your pelvis forward and open your hip up a bit. But that requires more core stability. If you don't have it you'll end up overusing your lumbar extensors and get back pain, or be too heavy on your hands and they'll be sore/tired/numb.

I'd say stick with what your current fit and just swap to a 165mm crankset. Don't change anything else so you can make an accurate decision on what effect the shorter cranks are having.

Who decided on 170-175mm being the crank length for 90% of the population anyway? That range is tiny compared to the range of heights, leg lengths, femur/tibia ratios etc. We definitely don't have a widely accepted scientific answer to the ideal crank length. So trying and seeing what feels best is a great option.


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 Post subject: Re: 165mm cranks
Posted: Mon Jan 23, 2017 11:20 pm 


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