|Is their a width difference between a DA and SRAM 9speed||Lone Gunman|
Aug 30, 2003 4:21 PM
|chain? Recently replaced some Ultegra parts for DA and a stock shimano ring for a TA specialties ring. I notice a slight tinging noise when in the 39x12 combo which is the chain ever so slightly touching the big ring in 1 or 2 spots. Pryed on the rings a bit to spread them but am wondering if the SRAM chain is a smidge wider than DA that is causing the noise. May just swap out the chain as well and go DA to find out as the chain does have about 1500 miles on it.|
|re: Is their a width difference between a DA and SRAM 9speed||Rusty Coggs|
Aug 30, 2003 5:31 PM
|DA 9 speed 6.6mm wide , Sram 6.9 wide. What are you dong in the 12x39 unless you have an 11?|
|Been riding it that way since day 1||Lone Gunman|
Aug 31, 2003 8:40 AM
|it nas NEVER been a problem. Frame is a Lemond Zurich, the original ring was a 42t. Got probably 12000 miles out of the original parts, the only reason I switched anything is I wanted to try a 39t ring on my triple setup, and needed to use a DA FD to make it work and keep my Ultegra crank.
So what I am thinking was correct, SRAM is a smidge wider which probably accounts for the chain touching the big ring. I see a Wipperman is on sale @ Nashbar for the same price I could get a DA and Connex link. Might a Wipperman be superior to a DA or is that splitting hairs in performance?
|Been riding it that way since day 1||Rusty Coggs|
Aug 31, 2003 9:52 AM
|Part of it is the circumference diff between the 42 and 39. Duno why you think you had to have a DA FD to make a 39 work??|
|Based the need for a DA FD on an article @ Peter White Cycles||Lone Gunman|
Aug 31, 2003 4:46 PM
|I bought a TA 39t ring for my Ultegra triple crank from White. According to White, who does not sell DA stuff so he has no reason to "push" DA components, Shimano Ultegra triple FD does not work when the difference in teeth between middle and big ring exceeds 10 teeth. I was using a 105 triple FD that was on my back up bike as I had stripped out the fix bolt on my Ultegra, and it did not appear to be fixable so I need a new FD anyway. I have no reason to doubt what White is saying in his article, as he is selling a product (TA rings) that is supposed to be Shimano compatable and he has a large customer base who want to customize their drivetrains. I always wondered why Shimano never offered a middle chainring for an Ultegra crank that is 39t, probably because of the +10 tooth difference thing and need to swap out the FD to change to a 39t ring. Can't use a DA 39t middle ring unless you do some metal shop work as the 30t ring bolts to the 39t ring, not the crank like Ultegra.|
|That's alot of BS||Rusty Coggs|
Sep 1, 2003 9:18 AM
|What shimano actually says is that the difference between the middle and big should be AT LEAST 10 teeth. Alot of people have used an ultegra or 105 triple ftont with 32/52-39 rings, including me.|
|riding 39/12 just wastes energy and wears out faster||Kerry Irons|
Aug 31, 2003 5:35 PM
|The sharper angles of going around the 12 means more drive train friction than the same gear ratio (85 inches) with a 53/16. Also, since your chain is engaging fewer teeth in the rear, the load is higher on both the teeth and the chain links, resulting in faster wear. What's the point? Finally, you must be a strong rider to move the gear (23-25 mph at 90-100 rpm cadence). Move to the big ring and ditch that triple?|
|As always, Kerry's advice is solid! Listen to it.... nm.||russw19|
Aug 31, 2003 8:39 PM
|There are hills in my area||Lone Gunman|
Sep 1, 2003 8:05 AM
|standing, in a 30x25, I am going 4mph, and sitting the front wheel pops off the ground with each pedal stroke. If all I did was tool around on MUTS paths, I'd ditch the whole drive train and ride a single speed. The smallest double chainring I had ever ridden prior to swapping out my 42t for a 39t was a 40t on my retro bike. The difference I notice 39vs42t is I ride a smaller cog in the rear, not a real big deal. I have no reason at all to ditch the triple, all that would do is cost me more money at this point.|
|OK, so ditch the 12||Kerry Irons|
Sep 1, 2003 5:10 PM
|If the hills are so steep that you need a 30x25, then there's no point in pedaling down the other side at 35 mph. You can coast faster (or at least as fast) and save the effort for the next climb. Start your cassette with a 13 and get another cog where you need it (maybe the missing 16, so you can have a 53/16 that will be the same ratio as your 39/12).|
|Need the 12 for the big ring||Lone Gunman|
Sep 1, 2003 5:54 PM
|Routinely catch 50-55mph downhill in these parts, usually spin out the 12x52, I use the full range of gears, I'm happy with what I have, just trying to eliminate a little chain rub.|
|And all I wanted to know was the different width of 2 chains nm||Lone Gunman|
Sep 1, 2003 1:32 PM
|And all I wanted to know was the different width of 2 chains nm||MShaw|
Sep 2, 2003 9:30 AM
|Yeah, but the question you asked means either no one ever told you to avoid the big/big and small/small combos, or you've just "forgotten." The tow extremes are BAD for the bike: wears things out.
Since you asked a beginner's question, you're getting remedial help.
The "prying apart the outer ring" thing scares me too. Don't do that! If the chain's rubbing, ride another gear that feels the same. That's the reason you HAVE gears! Rubbing and grinding are sounds that bikes make when they're not happy.
Anyway, the OP has been answered, along with a lot more information than you wanted.
Hope that helps (more),
|Found the same thing when crossing it over the other way||LC|
Sep 1, 2003 2:31 PM
|I can't see why you would use 39x12, but I do use 53x25 sometimes in a race up a short hill. On my Cannondale crossing it over it seems fine with SRAM chains. On my Ti bike it flexes and the SRAM chain rubs when I go hard so I use a Dura Ace chain and no noise. Seems that each bike has it's own preference of chain brand.
I would try to avoid the 39x12 cause if the frame flexes and you catch one of the bigs rings's teeth just right bad things can happen.