Road Bike, Cycling Forums banner

39 versus 42

608 views 7 replies 6 participants last post by  MShaw 
#1 ·
I am currently using a 42/53 front rings with 13-26, 8 speed in the rear. I am having a bit of a problem on bigger climbs and was wondering if changing the front rings to 39/52 would make much of a difference. Any advice from those with this experience? Steve
 
#2 ·
Three on the front = one on the back.
In other words, if you change to a 39, it will feel as if you had a 27 in back.
.
If you have Shimano, you could go as low as a 38, with a double crank.
 
#3 ·
Math

MR_GRUMPY said:
Three on the front = one on the back.
In other words, if you change to a 39, it will feel as if you had a 27 in back.
Ummmm... You're only half right - three on the front = two on the back (at least in the this case):

39/26 = 1.5 = 42/28

Going to a from a 42 to a 39 in the front would feel more like you went from a 26 to 28 in the back.
 
#4 ·
Assuming the above information provided, IMO, no you won't notice much difference. I suggest going with something like a 13-28, 13-29 or similar in the back with a 39 in the front. Or, if you are up for it:

1. Compact crank up front -- 34/50 or 36 /50
2. Triple up front
 
#5 ·
Rule of thumb (and you know how thumbs are), going back to that days when everybody rode a single speed, unless they were a Tourist.
Still used for track guys.
 
#6 ·
freewheel_steve said:
I am currently using a 42/53 front rings with 13-26, 8 speed in the rear. I am having a bit of a problem on bigger climbs and was wondering if changing the front rings to 39/52 would make much of a difference. Any advice from those with this experience? Steve
Keep the 42 and do an extra hill or two a week, soon it won't matter you're missing the 39.
 
#8 ·
All I know is that there ain't THAT much difference between the 42 and the 39. BTDT.

I DO know that there IS a distinct difference between a 23t and a 24t big cog. BTDT too!

To the OP: here's yer chance to upgrade! Go compact! Woot! Little gears that act like big gears. Rode the cross bike to work the other day with the 34/44t gearing in the front and the 'hills' between Morgan Hill and Gilroy weren't NEARLY as big. 'Course the top speed wasn't what it coulda been...

M
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top