|53X39 VS. 53X38.. OR MAYBE 52?||bicycle268|
Aug 25, 2003 12:25 PM
Lately I've been contemplating my gearing. I have always ran a 53x39 combo up front and currently run a D.A. 12-27 cassette. I've noticed that I tend to spend a good deal of 'big chainring' time in 17-23t and my 'lil ring' time is spent in the 15-27 range (lots of short, steep hills).
question: would switching out chainrings to a 53x38 or 52x38 open up my use of the 12-15 portion of the cassette?
|Doubt you'd feel a difference--I know I wouldn't.||retro|
Aug 25, 2003 1:55 PM
|One tooth just isn't enough to make a difference, at least not to me. You could calculate the gear inches and see what it would give you: Number of teeth in the chainring divided by the number in the cog times 27, the nominal diameter of the rear wheel in inches. A 53/17 would be about 84 inches, a 52/17 about 82.6. That's what, about 2 percent?
FWIW, I'm running a 46-36-26 triple. That REALLY opened up the small end of my cassette.
|I've been meaning to ask...||Frith|
Aug 25, 2003 3:19 PM
|What are the options on a shimano double crank (ultegra if it matters) what's the bcd and what chainrings could I get away with? |
sorry b268 not trying to steal your thread... just seemed like the right time to ask.
Aug 25, 2003 3:54 PM
|'cross guys are running 38/46-48t rings on 130mm bolt pattern cranks. 38t is as small as you're going to be able to get away with on a 130mm bolt circle.
The short and dirty way to figure gears is that one tooth in the back is worth 3 in the front. If you're running 50x12, it'll feel like a 53x13, etc...
The other thing you can do is go 110mm. Then you can go as small as 32-34t & 42-44t. Then you can run a smaller cassette (saving weight!) and get the same gear ratios. I think Rivendell still sells road double 10mm cranks.
|I THINK smallest is 38 or 39,...||retro|
Aug 25, 2003 4:02 PM
|Don't those use a 130mm bolt circle (I don't have any around to measure)? If so, I think the smallest possible is 38 or 39. I built my Atlantis with Rivendell's Sugino triple, which uses 110/74 circles and lets you go down to 34 teeth or so for the middle ring. The 46-36-26 is perfect for me, an aging recreational rider with big mountains all around.
Riv also has a Ritchey double with a 110 circle that it sells with a 46-34, I think it is. If I had to go back to two rings, that's what I'd use. With an 11-28 cassette, you'd have a range of 33-113 gear inches.
|Why do you want to use smaller cogs?||Kerry Irons|
Aug 25, 2003 4:44 PM
|This will increase chain wear and increaase drive train friction. Of course changing one tooth in front would have minimal impact, so it's purely academic.|
|re: 53X39 VS. 53X38.. OR MAYBE 52?||LC|
Aug 25, 2003 5:26 PM
|39 to 38 is not worth it and may not even fit with out some filing. 52 is nice, but you will hardly notice it unless your are racing or TT If you really want to make a difference then you should get a 50T big ring and a 36T small which means you need a whole new crankset with 110 BCD.|
|Go with a 50/38.......||Len J|
Aug 26, 2003 3:16 AM
|For most recreational riders, the only thing a 52 or 53 chainring is good for is giving you gears to pedal on descents.
You can get a 50 C/R from T/A in a 130 bcd, it will open up more of the gear range for you.
OPf course the more of a spinner you are, the faster the speed you can go in your smaller chainring, and the less you will use the big ring anyway.
|definitely a spinner||bicycle268|
Aug 26, 2003 6:15 AM
|I usually cover around 220-250 miles a week and consider myself a reasonably fit cyclist. Don't get me wrong, I love my 53x39 set up, it's just that cause I'm a spinner, I'm often not in the 12-13-14 on the flats and in the 15 only once in a while. I guess a one tooth decrease up front wouldn't make much of a difference afterall. It seems the only time I need the smaller cogs is in a time trial.|
Aug 26, 2003 6:25 AM
|I would definatly go with smaller front rings to open up more gears for normal riding. Look at what Tyler did for the tour because It was too painful to stand & hammer, he put on a 48/38 so he could spin the climbs.
|THANKS ... (NM)||bicycle268|
Aug 26, 2003 6:50 AM