Crash_Man

I'm going to replace the Ultegra Triples on my new Trek 5000. The stock 62cm came with 175mm cranks. But since I am going to replace them, I have the opportunity to go with 180mm.

What advantage would 180mm's give me? How do I know that I can successfully employ them with my leg length? I don't have a current inseam, but I'm 6'4", thats why I am getting a 62c bike.

Thanks

my58vw

Well I have a 175 on my road bike and a 180 mm on my mtb and their is a slight difference. Because of your height you will getr a little bit better extention in the crank, so you can have the saddle posistioned a little differently. You will sacrefice ground clearance though which could be a problem. It aslo seems like you will have to move your legs farther on each stroke. Of course it is only 5 mm difference...

wattsy_rules

There's been lots of discussion on this topic over the years. I read an article once (about 3 years ago) where the author argued that 175mm was just not enough length for some people. He had an algarythm that supposedly worked out the exact length each individual required. I'm 6" and according to this guy my ideal length was 182mm, but then I do have longer legs and a shorter body. I currently ride with 175's (Cause I can't afford Dura Ace) and would like to try the 180's.

galen_52657

If you ride a 62 cm frame and it fits, you need 180's

phantomcow2

Well still keep in mind 5mm is not a huge difference here. But since your tall 180 is probably a better buy. Im still growing and spent all this money buying parts for a guy whos 5' 8" and now im 6'

AndrewP

Its an extra 5 mm at the top and bottom of the stroke so you will have a total 10 mm extra leg movement

Fox Farm

I'm 6'2" and have been riding 175 cranks for 28 or so years. I borrowed a bike from a friend while traveling and the frame was just a little too small for me (58 C/C). On a hill, I stood up to crank and found that something just felt different in the way that my torque seemed to be transfered to the wheels. During a break, I looked at the inside of the crank arm and sure enough, it was a 172.5 So, you will feel or notice the difference in 5mm, but probably with regards to when you need to shift to an easier gear. It's like driving a car with small diameter wheels vs one with taller wheels. With shorter crank arms, the motor (you) will lug and need to be shifted when you hit grade. You can't just torque it as easy as with longer crank arms as the leverage is not the same with the shorter arms.

Crash_Man

I'm just worried about causing injury. Anyone have a formula or guide that will give me a better idea?

Gibbygoo

https://www.peterwhitecycles.com/fitting.htm

JavaMan

Longer legs need longer cranks. With 180's you will have more leg motion, more torque and probably lower cadence. If you get them instead of the 175's, don't forget to lower your seat 5 mm. I'm 6'4" and have had 180 mm cranks since 1990. I wish they were longer. I believe the 180's are only available in Dura Ace, which is about $100 more than the Ultegra.
Tom

fujiacerider

I'm 6'6" and recently switched to 195mm cranks. They RULE! On my favourite hill, I gained 31 seconds over the 175s I had on there before.
They also make our bikes look a little less weird.

Cole

53-11 alltheway

195's........yeah there was a guy on ebay selling those....he had two pairs. They would be too long for me sitting....but if I was standing I could probably leverage any hill with 'em in any gear

P.S. You might want to lone that pair of 195's to galen_52657 (with a little red star next to it) cuz he(inexperienced n00b rider compared to 53-11 ATW) is gonna need them when he races me......either that over a super duper quadruple chain granny special.

53-11 alltheway

I was just thinking about this during my ride Today.....Back when I had 175mm 105 cranks I wasn't really sure if the 180mm cranks would be faster. Honestly I bought the 180mm cranks just because I wanted a fuller range of motion. Coming from a weight training background Fuller range of motion exercise usually burn more calories and make for better exercise.

It turns out the 180mm cranks were faster...I also feel like I am getting a more complete workout than I used to with 175mm cranks. You knees come up a little higher after repositioning the seat with the 180mm cranks and It feels like i AM Working more of my legs.

For tall people who have been riding 170mm cranks for many years the 180mm cranks will seem awkward.....kind of like the guys in the gym who only do "half squats"......as soon as they try to do a full squat they notice the weakness in the muscles at the bottom of the lift.

The cranks I bought were about $200 ( 7701 9 speed DA cranks), but considering how much people spend on carbon fiber stems( which do nothing but save <10 grams of weight) it was a high value purchase in my case.

galen_52657

195's might be a little too long for me...I wonder if he coasts around the all the corners... but 185's (readily available!) might be fun to try.

Personally, I would not adjust my seat height with different length cranks. I have 177.5’s on my old bike and the seat height is the same as the newer bike with 180’s, as measured from the center of the crank.

Longer cranks allow the rider to stay seated longer, apply more leverage to the pedal and carry a larger gear up a hill and particularly, over a rise. They do not necessarily reduce cadence. They may slightly inhibit acceleration, but IMHO, sprinters are born, not made and they guys with a lot of fast-twitch will win no mater what crank length they are running….

53-11: Perhaps you would like to compare district medals???? Before or after I lay waste to your large arse…???

bikerski

where can I order longer cranks on line?

galen_52657

This should get you started....


https://www.peterwhitecycles.com/zephyr.asp

https://aebike.com/site/page.cfm?PageID=30&SKU=CR0837

https://www.branfordbike.com/crank/part/cr1pr2.html

https://www.excelsports.com/new.asp?p...jor=1&minor=13

bikerski

thanks

Thylacine

I think everything should be in proportion to your size, it makes sense. Cranks are no different.

I'm 6ft 4ins and run DA 177.5's. I could probably easily go to 180's, but trying to find 180+ cranks to replace my 180's on my singlespeed would probably cause me headaches.

Apparently Roger Durham of Bullseye cranks fame is still making a few cranks. I might have to look him up one of these days.

53-11 alltheway

Galen.......Where are 185's readily available?

You mention Peter white, but he will only sell you 185's if you buy a complete bike?

JavaMan

I'm curious about why you think you might be injured from using longer cranks? Do you mean injury due to greater leg movement, injury due to a crank arm hitting the ground, or what? When walking, you probably take longer strides than someone of average height. Has the extra leg movement caused you any injury?

As far as a formula or guide, divide your inseam by the average inseam and multiply by 170. For example, if your inseam is 36" and the person of average height (who uses 170 mm cranks) has an inseam of 32", then 170*36/32=191.25. There, in this example, you should have 191 mm cranks.

I think bike makers discourage longer cranks because they would have to raise the bottom bracket, which would require more fixtures, patterns or whatever.
Tom

53-11 alltheway

If anything it should be easier on knees in any given gear!

P.S. Wider handlebars go great with longer cranks.....makes for very nice riding position.

My older bike had 40cm handlebars (which I mistakenly thought would be more aero....except for the fact you can drop more comfortably with wider bars....so it cancels out and probably is in the 46cm handlebars favor)

Crash_Man

I have a knee that tends to get "cranky" when I don't treat it with due respect. This Trek 5000 is my first road bike. It's sitting in a warehouse waiting for me to pay it's bail. Once I get on it, I want it to be set up for me and not cause me any undo pain.

Looks like 180's are the way I'm gonna go. Now I just have to go find them.

53-11 alltheway

please tell me you are getting 46cm bars with those......especially a guy who is 6'4".

JavaMan

You'll wonder how you ever got along without them
Tom