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Re: Too short of a crank? [Fuller] [ In reply to ]
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Better knee angle
Better torso / hip angle
Better endurance
Aero benefits (due to being able to hold position)
More watts
It just feels better. //


What if you only got two of the listed above, would that not be worth it too? You seem to be arguing from a position of you just haven't tried it yet, so someone tell me conclusively why you should get shorter cranks. Its great that your fitter has the adjustable cranks, and you both seem to agree that there is no loss of power with the shorter ones. So what are the possible downsides that everyone is talking about?? And the one you left out besides holding aero position longer, is the actual static aero position they will afford you.


Like Dave said, best to just try it out after accounting for all the other micro adjustments you must make for a really informed comparison. And it you just get one of your list, and lose nothing, seems like it would be the thing to do, no? I raced an entire pro career on 175's and now ride in a much better, more comfortable and aero position with my 155's. I got virtually all of your list, except more watts. Faster on the same watts, but no more...
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Re: Too short of a crank? [alaska848] [ In reply to ]
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alaska848 wrote:
Shorter cranks are all the rage right now and for good reason, as several other threads have noted. However, is it possible to go too short? I've come across various "studies" that show benefits of extremely short cranks but how do these play out in the real world?
I think the answer to this depends on two fairly big factors.

First, what is short? A short crank for someone who is 6'3" is generally not going to be similarly short for someone who is 5'3". A "short" crank is a relative term.

Finally, a short crank that seems to work well on the flats will not necessarily work as well for the same rider in the hills or mountains. So if you ride only flat terrain you might go one way, vs if you ride on varied terrain.

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Re: Too short of a crank? [DarkSpeedWorks] [ In reply to ]
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Length is relative; I agree. I do mean short based on height. I saw a video that talked about Frodo riding on cranks that were roughly 20% of his seat height or something along those lines. He is riding short cranks for his height compared to other riders that are much short yet use the same length. I'm just curious about the experiences of others regarding experimenting with shorter and shorter cranks. Findingfreestyle's chart is similar to what I've noticed with myself as far as seat height and crank length. Two questions for you (and everyone else):

1. How much of an impact does crank length have on climbing? Froome for example, spins at a ridiculously high cadence. Does preferred rpm impact this scenario more than crank length?

2. What about frame size and crank length? How much different would a TT position on a size 56 (for example) be compared to a size 54 with the same crank length? Just for the sake of clarity, I mean a 56 with a larger stack and reach than a 54. I know sizing varies across manufacturers.
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Re: Too short of a crank? [monty] [ In reply to ]
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Not a reply to Monty, but to some of the general sentiment that feel is not sufficient and more hard science is needed. I would gently suggest that shortening cranks at the proper time during a bike fit is often not a very subtle change. Especially for shorter riders or those who I would refer to as massively over cranked, it can be quite obvious and profound. The two most common responses are "holy shit!" and "is this the same resistance?"

Other than the time between trials aspect (usually 2 minutes or less), the process is basically the same as adjusting seat height based on rider feedback. Too low, too high, or just right, and the same resistance will feel harder or easier. In other words, manipulate certain body angles and the bio-mechanics are impaired or improved. Adjusting seat height and changing crank length are very, very similar in that regard.

Don't go down the leverage rabbit hole, unless you are ready consider leverage on the bike as a function of 7 distinct fixed levers plus one rider variable continuous lever (aka - you gears).


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Re: Too short of a crank? [FindinFreestyle] [ In reply to ]
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I reckon I'm just going to have to work this out between me and my fitter. I think if I present this as an avenue we need to go down he will oblige me and we'll work it out together. I had hoped to avoid the expense of replacing brand new parts on my Speed Concept but I may convert to a 1x front mech anyway so a different crank arm length with a power meter might be in my future.

I'd like to add that I'm really not trying to be argumentative and I appreciate everyone's take on the situation (and I didn't mean to hijack your thread Alaska848)

Maybe we can add "your crank is too long" to the inevitable "your seat is too high" when discussing the next bike fit thread.

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Last edited by: Fuller: Dec 3, 18 13:32
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Re: Too short of a crank? [FindinFreestyle] - so where does one find shorter cranks? [ In reply to ]
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Hey there- vertically challenged cyclist here. I'm 5"3 and generally fit on a 48cm frame. I'm looking to upgrade and get a new triathlon bike. I want to purchase the bike and have it built with the correct cranks, and not have to swap things out afterwards. If I wanted to move to a 155mm size, which manufacturers actually sell them???? Can they be easily put onto any chainrings? My current (old) bike is custom sized for me, with 650 wheels- and it has a compact 34/50 on it. I really do like having the compact on there, so am trying to spec that as well.

I can't see that Shimano or SRAM have these small sizes- who does?
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Re: Too short of a crank? [FindinFreestyle] - so where does one find shorter cranks? [mtrichick] [ In reply to ]
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Cobb.
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Re: Too short of a crank? [FindinFreestyle] - so where does one find shorter cranks? [mtrichick] [ In reply to ]
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Rotor has down to 150mm cranks in 30mm axle width (not compatible with BBs specc'ed for 24mm axles). They are difficult to order though.
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Re: Too short of a crank? [bloodyshogun] [ In reply to ]
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Our XS Tactical come standard with 155 crank arms and dual InfoCrank power meter.

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Re: Too short of a crank? [FindinFreestyle] - so where does one find shorter cranks? [mtrichick] [ In reply to ]
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Rotor does
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Re: Too short of a crank? [alaska848] [ In reply to ]
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alaska848 wrote:
However, is it possible to go too short?

Okay, this may be irrelevant to the Tri community but what the heck: In my lab we collected some pilot data on maximal pedaling rate with (really) short cranks. The lab record is 338rpm and that was with 95mm cranks. Lengths below that became difficult to coordinate. Yes, this was during maximal short sprints and may not be at all useful for TT or Tri cycling.
Cheers,
Jim
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Re: Too short of a crank? [imswimmer328] [ In reply to ]
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I don't think their new ones do...... just older styles. Which I guess would be OK provided I never needed to replace them like-for-like.
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Re: Too short of a crank? [FindinFreestyle] - so where does one find shorter cranks? [mtrichick] [ In reply to ]
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My experience:

Cobb to 145, no power
Rotor to 150, with axle-based power meter if desired
Infocrank to 155, with crank-arm-based power meter if desired
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Re: Too short of a crank? [dkennison] [ In reply to ]
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dkennison wrote:
Our XS Tactical come standard with 155 crank arms and dual InfoCrank power meter.

Just for highlighting purposes. What size wheels does the xs come with?

How many other companies offer a well proportioned bike for small riders?
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Re: Too short of a crank? [bluntandy] [ In reply to ]
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Our XS comes with 650 wheels.

*******************
Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
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