I ride a variety of bikes with a variety of crank lengths. Being short- I like to use 165mm cranks on the road bikes or at the most 170. I only have a 30" inseam but I find that the 165's are more comfortable on the hills as I can keep the cadence higher.
Can hear you all saying B.S. at that but in fact I cannot feel any difference between the 165's and 170's. MTB's though and I use 175's. No idea why but probably the replacement cranks were bought on a deal and this was probably the only size available.
But Yesterday- My Son-in-Law (Ross) bought his bike round for a service. He is commuting to work now and 100 miles a week and the bike is getting worn. This is the FCR1 that I bought for my "Possible" commute- and he used to borrow my TCR-C when he rode with me. He now has the FCR on permanent loan and he is using it.
So up on the stand and clean the chain-1,000 miles on it and still not worn. Rear cassette OK but the big chainring is getting worn. Didn't like the look of it but I did not have any spare chainrings available. But sitting in the roof of the shed is my spare Compact Crankset from when I changed the TCR to a triple. So I changed the complete crankset. Easier than changing chain rings but as this was not a shimano version- I had to change bottom bracket aswell. Bit of adjustment on the Front derailler and I lost the rubbing he had in the small ring and large cog on the cassette. Few other minor things to do but 30 minutes and the bike was ready to roll again.
Then I got the phone call tonight. "What the Hell had I done to the bike"? My mechanicing skills are superb as he managed a higher speed on the flat on the commute into work. The hills seemed a lot easier and in fact must have been as he was one gear higher and the bike felt a lot more comfortable. Then on the commute home he rides with a few of his workmates for about 5 miles and they always have a competitive edge to them. One of the work mates races for a local club and Ross always managed to stay with him on a slight rise but struggled. Tonight and Ross Pushed him all the way and at the end felt good. "So what had I done to the Bike"?
So I told him- I had swopped his cheap Shimano Crankset for another one and he now has 175 cranks on it. Only a Truvatif Elita but this was the set that the shop supplied wrong to me on the TCR I had bought as it was not the 165's I normally use. The original Shimano set were 170 but as he has longer legs than me- I thought he might enjoy a longer crank. He apparantly does.
I have always said that a 5mm change in crank length will not make a difference to the average rider. 10mm did for me and that is why I had a spare crankset that I could afford to lose. But the way Ross is raving about the bike tonight- I am beginning to wonder. Just changing the crank length has made a lot of difference for him- So I might have to try out the 170 cranks on Boreas. After all- My spare crankset is now that size--- Even if it does have a worn ring on it.