Double to Triple
08-12-07, 06:10 AM
#1
Cries on hills
Thread Starter
Join Date: Jun 2007
Location: Central NH
Posts: 1,088
Bikes: 2007 Trek Pilot 1.2, 1969 Raleigh Sprite 5
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 83 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Double to Triple
Yet another, I know.
I have a Sakae (Sakae CX?) double, 40/52, and I measure 110mm BCD. Currently, with an SIS 30/25/21/18/15/13 freewheel. The 40/30 is good enough for most hills, but I wouldn't mind a bit more. Shifters are Z401; FD is Z202, RD is Z501--all Shimano. All components seem to be in good shape (at least I think they are).
What could be reused? Or am I looking at a new crankarm and chainrings and bolts and FD and RD?
I have a Sakae (Sakae CX?) double, 40/52, and I measure 110mm BCD. Currently, with an SIS 30/25/21/18/15/13 freewheel. The 40/30 is good enough for most hills, but I wouldn't mind a bit more. Shifters are Z401; FD is Z202, RD is Z501--all Shimano. All components seem to be in good shape (at least I think they are).
What could be reused? Or am I looking at a new crankarm and chainrings and bolts and FD and RD?
08-12-07, 08:22 AM
#2
Elitist Troglodyte
Join Date: Jun 2006
Location: Dallas
Posts: 6,925
Bikes: 03 Raleigh Professional (steel)
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
With friction shifting on the front, you need the crankset/BB and FD.
The question mark will be the RD. Your current RD only has to handle a 10T drop in the front. You might need a long cage. Z501 came in long-cage version RD-Z501-GS. Picture?
The question mark will be the RD. Your current RD only has to handle a 10T drop in the front. You might need a long cage. Z501 came in long-cage version RD-Z501-GS. Picture?
__________________
Stupidity got us into this mess - why can't it get us out?
- Will Rogers
Stupidity got us into this mess - why can't it get us out?
- Will Rogers
08-12-07, 10:12 AM
#3
Senior Member
Join Date: Jul 2005
Posts: 7,487
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked 162 Times
in
89 Posts
If the crankset has a 110 BCD as you say, another option is simply a smaller chainring. You can go as small as 33t with a 110 BCD. Doing that, you might want to put a slightly smaller big ring on, too, for better front shifting, but you could try it first. 50/34 is pretty typical for a "compact" double crank(110 BCD)-
P.S. Depending on the RD's chain wrap capacity, you might end up needing a new one even with just the smaller chainring. 50/34 with your 13 x 30 freewheel, for example, has a 33t max chain wrap requirement-
P.S. Depending on the RD's chain wrap capacity, you might end up needing a new one even with just the smaller chainring. 50/34 with your 13 x 30 freewheel, for example, has a 33t max chain wrap requirement-
Last edited by well biked; 08-13-07 at 09:27 PM.
08-12-07, 10:53 AM
#4
Cries on hills
Thread Starter
Join Date: Jun 2007
Location: Central NH
Posts: 1,088
Bikes: 2007 Trek Pilot 1.2, 1969 Raleigh Sprite 5
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 83 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Well, I looked--definately non-GS. But the distance between the plastic wheels is 75mm, which is the same as the RD on my MTB. I shifted into 40/13, and it still has some takeup left in the RD, so I could probably just drop down the chainrings.
I'm a bit hesitant now: lately, I've been riding 4th or so in the small chainring, which means decent chainline, and hopefully decent wear, along with reduced friction. If I change the chainrings, I'll wind up having to use the big gear more often. Hmm, I was hoping to use the chainrings based upon incline, and not have to regularly shift across them. But I'm not about to go swapping out all the parts. Maybe I'll dig around for a 50/34, as suggested (or maybe not as severe), and maybe swap back and forth, and see if I like it or not.
Thanks all for the help.
I'm a bit hesitant now: lately, I've been riding 4th or so in the small chainring, which means decent chainline, and hopefully decent wear, along with reduced friction. If I change the chainrings, I'll wind up having to use the big gear more often. Hmm, I was hoping to use the chainrings based upon incline, and not have to regularly shift across them. But I'm not about to go swapping out all the parts. Maybe I'll dig around for a 50/34, as suggested (or maybe not as severe), and maybe swap back and forth, and see if I like it or not.
Thanks all for the help.
08-13-07, 09:12 PM
#5
Newbie
Join Date: Aug 2005
Location: La Mancha (Spain)
Posts: 4
Bikes: Steel Columbus Genius. 46/40 and 10-speed 12/27
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I suggest you new chainrings of 38 and 50 teeth.
The gap of gearing from 38X18 to 50X21 is only sligtly bigger than the one existing between 40X18 and 52X21, so you would change between chainrings at a lower speed, but still changing from the 18 to the 21, and your chain shouldn't be less aligned.
Climbing with a 38X30 is almost the same than with a 34X27 which is more than enough for me.
It's true that you could find the 50X13 a little short when descending.
These are the speeds (miles/h) you reach pedaling at 95 r.p.m. now:
30 25 21 18 15 13
40 10,01 12,01 14,30 16,69 20,02 23,10
52 13,01 15,62 18,59 21,69 26,03 30,03
And these what you would reach with the 38/50 theeth pair:
30 25 21 18 15 13
38 9,51 11,41 13,59 15,85 19,02 21,95
50 12,51 15,02 17,88 20,86 25,03 28,88
Another option:
30 25 21 18 15 13
36 9,01 10,81 12,87 15,02 18,02 20,79
48 12,01 14,42 17,16 20,02 24,03 27,72
The gap of gearing from 38X18 to 50X21 is only sligtly bigger than the one existing between 40X18 and 52X21, so you would change between chainrings at a lower speed, but still changing from the 18 to the 21, and your chain shouldn't be less aligned.
Climbing with a 38X30 is almost the same than with a 34X27 which is more than enough for me.
It's true that you could find the 50X13 a little short when descending.
These are the speeds (miles/h) you reach pedaling at 95 r.p.m. now:
30 25 21 18 15 13
40 10,01 12,01 14,30 16,69 20,02 23,10
52 13,01 15,62 18,59 21,69 26,03 30,03
And these what you would reach with the 38/50 theeth pair:
30 25 21 18 15 13
38 9,51 11,41 13,59 15,85 19,02 21,95
50 12,51 15,02 17,88 20,86 25,03 28,88
Another option:
30 25 21 18 15 13
36 9,01 10,81 12,87 15,02 18,02 20,79
48 12,01 14,42 17,16 20,02 24,03 27,72
