mikemowbz

I'm just kicking off a build on a 25" Nishiki Prestige, and specifically looking for some input on the subject of crank length.

It seems common for tall bikes from the 1980s, like my old 25" Norco (https://www.flickr.com/photos/baddest...in/photostream), which had 170mm Shimano 600 Arabesque cranks, to have what some might consider a shorter crank than I've been recommended as ideal for my height. Presumably, these larger frames had folks my height (6'3") in mind. Yet I'm told that I ought to prefer a 175mm or perhaps a 172.5mm crank.

What's up with that? Have standards changed, or...?

In looking at a crankset to put on my sprightly Nishiki frame (thread on the frame and prospective build here: https://www.bikeforums.net/showthread...estige-25-quot), I'm tending to think that I ought to go with the longer crank arm (I'm still looking, but perhaps a Sugino VP or Maxy, an old no-frills Dura-Ace, or a Campy Centaur that I found with some scratches to bring the price down - the latter two in 175mm and the former in 172.5). This might seem like a bit of a newbie kind of a question, but is the longer crank arm a good move on my part? Like I said, 25" frame (62cm c-to-c), I'm hoping to build it up for fast rides around Vancouver's many bike routes, which means a lot of hills, but not into competition or anything like that ; I'm 6'3" with approx 35" inseam (and pretty heavy at ~250lbs).

Do I go with the extra leverage? Or do I stay true to the build typical of these bikes back in the day?

mazdaspeed

Try riding it. 170mm cranks really hurt my knees, but if you can handle it, it shouldn't be a problem.

toosahn

I'd go to 175 or 180mm on my 62cm Mikkelsen if I could

mikemowbz

I rode the 25" Norco I mentioned with 170mm 600 cranks quite a bit, but just in the city - it did seem a little troublesome for longer rides, though. What I'm dealing with now is just a frame/headset/seatpost that requires cranks and everything else to be built up. What really makes me curious is what - based on a really small sample - seems like a trend on 80s road bikes (at least Norco and Nishiki, from what I've seen) to go with these short cranks. Why'd they do it? I don't know. In any case, I think I'm a lot more likely to go with the longer cranks...

Velognome 

I ride 25" frames and prefer a longer crank, like a 185. If you think about it ( dangerous I know ) a 25" frame is roughly 9% larger than a 23". You'd expect a 170 crank on a 23", scale it up 9% and you've got a 25" with 185 cranks. Pedal strike? I ride a 25" fixed with 185 cranks, no problems.

mikemowbz

I didn't even know 185mm was an option! Mostly I've seen 180s on BMXs. I'm going to look into this more...

Because when I do think about it, it kinda makes sense! Definitely not a 170 or 172.5 set, in any case.

Velognome 

Haven't been able to find any traditonally styled new cranks sets at 185mm but I'm not that much of a style junkie unless it's a period piece intended for short rides. I'm 6'2" and like to ride long distances so the 185's are all about comfort. And really without a rule can you see the a 10mm difference? Doubt it, but you can sure feel it!

photogravity

I've got cranks ranging from 148 (shortened by Mark Stonich) up to 175 and don't have a problem with any of those lengths. I tend to spin faster on the shorter cranks but none of the cranks hurt my knees any more than another doing the rides I'm doing which range from 2 to 45 miles.

EDIT: I'm about 5' 9" tall.

choteau

Go with the 175's. My 80's miyata (25" frame ) has 165's and they tend to make my knees hurt, while my old roadster with drum brakes weighing 55+ lbs doesn't (it has 180's)

rhm

^^^Don't listen to any of 'em!

Check the bottom bracket height, clearance between pedal and ground (when leaning), and clearance between toe and front wheel (when turning). If you are absolutely convinced there's extra space, you can consider longer crank arms, but even so, don't expect them to change much or anything.

I'm 6' tall and prefer shorter crank arms, something in the 150-160 range is nice, though 165's or 170's are okay if that's the only choice.

choteau

If your a spinner go with shorter, if a masher go with longer. My Miyata with 165's cruising gear = 60.8 inchs, while my old roadster with 180's cruising gear is 61.4 inchs. Since the Miyata's are arms are 9% shorter, at any given RPM the roadster takes about 9% less effort to turn. My 54 year old arthritic knees and hips can tell the difference... 6'2" Tim ( 60-80 RPM all day )

Velognome 

Good advise about the toe overlap, really it's good sound advice.......but since you've been instructed not to listen....sigh....I'll just head out to spin some big circles with my long cranks.

PS...crank size does matter, only guys with 160mm or less will tell you otherwise

mparker326

I'm 6"5' and ride anything from 165's to 175's. Honestly, I can't tell the difference. I had 175's on my Schwinn Voyageur and had terrible toe overlap issues. I now run 165's on it and it made a difference with toe overlap.

If I were you, I'd just ride with those nice looking Shimano Arabesque 170 cranks & call it day.

zandoval 

Don't forget crank length can effect toe clearance of the front wheel when turning - This can be a real nuisance...

blaise_f

I ride 140s all the time and haven't ever noticed any issue (or ease on more modern cranks, as a matter of fact). Find what's comfortable for you.

fuzz2050

I'm also one of the crowd who just can't tell the difference. Go with what looks pretty.

mikemowbz

So this thread has definitely established that there's a diversity of opinion on the matter. I feel like I am a bit of "masher" as choteau put it, rather than a "spinner" - obviously I don't use my gears as efficiently as I could, in fact I usually made use of all of three speeds in Montreal, and 5 or so in Vancouver (which has a lot more incline built into the topography). That's how it's been up to now in any case. I'm thinking I'll stay away from an exceptionally long arm (for a couple of the reasons mentioned, mainly clearance - not to mention the difficulty of getting a set that looks 'right' for a classic kind of build). I'm intrigued, though, by the idea of a 180-185 length - even though there seems to be a lot of thinking by some to indicate that it's not a big deal, or possibly even a bad idea. I'll have to try this out, as it makes sense to me that there would be at least a nominal advantage. But hey, what do I know? For now, I think I'll aim for a nice clean Shimano 600 or Sugino crank at 175mm to add to my 25" Nishiki Prestige. Now I just have to find the right set! Maybe pick something up on a visit to NYC this coming week...

rhm

The best thing about long crank arms is that when you put them on a fixed gear bike, you can get totally airborne when you lean into a turn. Sideways, too!