Dura Ace 172.5 vs 175

[wisecrack]

What difference will this small difference (2.5cm) make to my riding?

 

I am quite tall 1.89m and my old crank(105 grouppo) use to be 1.75.

 

My new Dura Ace crank is 172.5 I havent really notice a difference in power.

 

I have the opportunity to swop my 172.5 crank for a 175, but wondered if this would really make a difference to let's say my climbing on hills taking in account that I'm a tall rider with rather long legs. 

[gummibear]

The shorter the crank arm the faster you can spin and the longer it is the better leverage on climbs.look here is a table for avg sizes.

 

Frame Size

Crankarm

Inseam

Crankarm

54 cm or less

170 mm

80 cm or less

170 mm

55 - 58 cm

172.5 mm

81 - 86 cm

172.5 mm

59 cm or greater

175 mm

87 cm or above

175 mm

[wisecrack]

TRhanks for this windblown.

[Icycling]

also depends on your riding style - if you like to spin or if you are a junior with restricted gears then 172.5mm are great.

 

 

 

If you like to use big gears then go 175mm or even 177.5mm

[Christie]

Won't make much of a difference. From velonews.com:

 

His studies of 16 bike racers of various heights doing maximal sprint power tests of under four seconds duration on cranks of 120, 145, 170, 195, and 220mm showed no statistical difference between crank lengths. Seat height to the pedal was maintained throughout, but fore-aft saddle position and handlebar height were not readjusted with crank length changes, despite variations with crank length of pedal-to-knee relationship and saddle-to-bar drop. This also led to Martin?s assertion that he could see no point to positioning the knee over the pedal spindle.

Further Martin tests showed no statistical relationship between metabolic cost and either pedaling rate (RPM) or crank length, using nine trained cyclists riding 145, 170 and 195mm cranks who pedaled at 30-, 60-, and 90 percent of their lactate threshold at 40, 60, 80 and 100 RPM. On the contrary, power output and pedal speed (pedaling rate times crank length), accounted for over 98 percent of the variation in metabolic cost.  

 

http://www.velonews.com/article/13978

 

 

[zerocool]

HI Christie,

 

I have the same problem! Can't decide what to do and what will work best! I have a great PowerPoint presentation by the best in the world. PM me your email and ill send it.

 

Im 185cm and went for the longer 175mm cranks.

 

[Sequoia]

Won't make much of a difference. From velonews.com:

 

http://www.velonews.com/article/13978

 

 

 

Interesting article. I agree. I have 180's on my road bike and mtb, 175's on my single speed play bike and 170's on my commuter. I can spin the 180's at the same rate as the 170's and although I *think* I can feel a difference (making larger circles and all), I chose the long cranks more for the reduction in seat height that they gave me, than for leverage advantage. I have a 98cm inseam, so my saddle is m*erse high.

But Mr Zinn is making good money out of 200+mm cranks, so there is definately a demand for longer cranks.

[Christie]

How I see it, for roadies the bottom line is that if you already have a crank, dont worry about how long it is!

If you are buying a new set, I suppose you can look at the crank length formulae, the table windblown posted above look like a good guide.

[Anticlimb]

Won't make much of a difference. From velonews.com:

 

http://www.velonews.com/article/13978

 

 

 

Interesting article. I agree. I have 180's on my road bike and mtb' date=' 175's on my single speed play bike and 170's on my commuter. I can spin the 180's at the same rate as the 170's and although I *think* I can feel a difference (making larger circles and all), I chose the long cranks more for the reduction in seat height that they gave me, than for leverage advantage. I have a 98cm inseam, so my saddle is m*erse high.

But Mr Zinn is making good money out of 200+mm cranks, so there is definately a demand for longer cranks.

[/quote']

 

I  have 180's on my full sus mtb . The problem with those are that it sometimes hits the floor and it has brought me down twice already . Was thinking of going 175 mm , but will it realy make such a difference ?

[FlyingCheetah]

 

I  have 180's on my full sus mtb . The problem with those are that it sometimes hits the floor and it has brought me down twice already . Was thinking of going 175 mm ' date=' but will it realy make such a difference ?

[/quote']

 

If it doesn't hit the floor and bring you down, I bet it WILL make a difference...

 

FlyingCheetah2008-03-20 02:40:16