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Conference noted::bicycle

Title:	Bicycling
Notice:	Bicycling for Fun
Moderator:	JAMIN::WASSER

Created:	Mon Apr 14 1986
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	3214
Total number of notes:	31946

860.0. " CHANGING CRANK & CHAINRING SIZE " by USMRM5::MREID () Thu Sep 08 1988 20:44

    I recently changed the crankset on my bike:
    
    From: Shimano 600		To: Sugino 75 Carbon Fiber
          172.5 cranks		    175.0 cranks
    	  52 x 42 rings		    54 x 42 rings
          (2 years on this setup)   (2 weeks on this setup)
    
    I mainly ride time trials & road races, so I didn't care about the
    loss of cornering angle in going from 172.5 to 175.0 cranks. I was
    hoping the larger cranks would give me more power (leverage) in
    my time trialing & hillclimbing. The 54 x 12 is also a massive gear
    that is great for big downhills. I'm 5'11" and weigh 165.
    
    I haven't seen any improvement in my TT times yet. Last night I
    rode the Wayside Inn TT a little slower than usual (first time doing
    the TT with the new cranks...)                                       
    
    THE QUESTION IS:  has anyone else experimented with changing crank
    length or chainring size? Does it just really take a while to get
    used to? (I have 100-200 miles on the new setup). Did you change
    your seat height? Has anyone found or heard of any advantages or
    disadvantages of longer cranks & larger chainrings? 
    
    Mark

T.R	Title	User	Personal Name	Date	Lines
860.1	Read note 181 and its replies	CESARE::JOHNSON		`Fri Sep 09 1988 07:23`	12
	You probably got them at Bike Markbar on sale, right? Well, I think you may have paid too much. Another year after note 181's replies were written, I can't claim any performance improvement. Don't get me wrong, I wouldn't part with my 175s, but I think of the choice as something peculiar to my tastes, not an "edge". MATT PS -- Replacement rings cost a fortune for that set-up, and you're eventually going to need something besides the 54. (You can pay them now, or pay them later....)
860.2	my $.02	UMBIKE::KLASMAN		`Fri Sep 09 1988 12:50`	15
	< Note 860.0 by USMRM5::MREID > -< CHANGING CRANK & CHAINRING SIZE >- About a month ago I switched from a 52 to a 53 and I am riding faster than before. I've taken about 2.3% off my usual TT time (from 29:00 to 28:20 on an 11.2m course) and about 3.7% off of my Century PR (from 5:27 to 5:15, thou on vastly different courses). I don't know if its the 53, but I'm somewhat surprised that I could push it, and consequently I feel very strong. I've always ridden 170 cranks, which is long if you go by what Shimano is shipping on new bikes in my size (165's on 52cm frames). I would definitely not go down to 165's, since I'm comfortable with the 170's. I would fear a loss of power. Kevin
860.3		PSG::BUCHANAN	Bat	`Fri Sep 09 1988 17:57`	32
	1) I'v often wondered why frames, stems, bars, toe clips, etc. all come in different sizes but crank arms arms were one-size-fits-all. While this is begining to change I would say that >90% of the bikes still come with 170's. Does anyone know that something like the FIT-KIT says about this? When I put together my bike I asked if I shouldn't have longer cranks (I'm about 6'1" and ride a 58 frame). I had 175's on a mountain bike which I would ride on the road with cleats and could spin just as fast with no problem. I got 175's and to tell the truth I can't feel a bit of difference. Or maybe I do feel a defference but it's masked by being a different bike. I asked the shop owner what the pros use and he said that Greg LeMond who's about 5'6" used to use 175's but was currently using 172.5's. It's just something that you work out, what do you want to maximize, leverage/torque or spin. 2) Switching to a 53 (or even 54) would give you a higher TOP gear but what about the gears in the middle? For any given terrain you want to find the perfect gear, but you only have 14 (of which 4 you never use) so you settle for one that is closest. If you are riding a 52x20 switching to a 53x20 might be too high so you must go to a 53x22 or switch to the 42 chain ring. Before you switch make a gearing chart and see which one give a better selection of gears. You will find that some combinations offer a bunch of duplicate gears which is a waste. I use 175 cranks and gears of (42,53) - (13,15,17,19,21,23,26). While some supermen would call 42x26 a granny gear there are times I wish I had lower, not higher gears.