bakalboy
XC Rider
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Posts: 112
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Post by bakalboy on Mar 23, 2008 19:59:40 GMT 8
just purchased(pay when able ;D) roadbike and installed the new tiagra compact crank coz the 54/39 truvativ touro that came with the bike is too large for me. problem is the cranks shifting is far from ok. question #1: - are there really no spacers for the tiagra's outboard BB? pardon my ignorance coz i'm used to mtb BB's with 3 spacers. question #2: - should i change my fd? i've messed with the limiter screws and cable slack, still no luck with the shifting on the cranks. i'm contemplating to put a spacer on the drive side of the BB. hope you can enlighten a newbie roadie. thanks i advance.
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Post by enzo on Mar 23, 2008 22:49:01 GMT 8
just purchased(pay when able ;D) roadbike and installed the new tiagra compact crank coz the 54/39 truvativ touro that came with the bike is too large for me. problem is the cranks shifting is far from ok. question #1: - are there really no spacers for the tiagra's outboard BB? pardon my ignorance coz i'm used to mtb BB's with 3 spacers. question #2: - should i change my fd? i've messed with the limiter screws and cable slack, still no luck with the shifting on the cranks. i'm contemplating to put a spacer on the drive side of the BB. hope you can enlighten a newbie roadie. thanks i advance. brad, If your bottom bracket shell is 68mm, then you need spacers. Congrats nga pala sa new roadbike mo.
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bakalboy
XC Rider
today is the best day to ride!
Posts: 112
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Post by bakalboy on Mar 27, 2008 12:35:42 GMT 8
an answer from the D' Man himself. the bb shell is 73 sir. i guess the problem is the fd. the one installed is a campy avanti. it's shifting ok now but not as fluid as i wished it would. i'll try to replace the fd. thanks sir enzo!
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Post by flipnidaho on Mar 27, 2008 19:43:43 GMT 8
if you went from regular to compact, you also have to adjust the height of the derailleur. When in the biggest ring, the bottom of the derailleur cage should be aboue 2 or 3mm above the chainring's teeth and perfectly parallel with the chainrings (as viewed from the back of the bike). You may also need to subtract some links from your chain as well...
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bakalboy
XC Rider
today is the best day to ride!
Posts: 112
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Post by bakalboy on Mar 29, 2008 10:01:37 GMT 8
if you went from regular to compact, you also have to adjust the height of the derailleur. When in the biggest ring, the bottom of the derailleur cage should be aboue 2 or 3mm above the chainring's teeth and perfectly parallel with the chainrings (as viewed from the back of the bike). You may also need to subtract some links from your chain as well... thanks for the reply sir flipnidaho. already did what you said but i still can't get smooth shifting . i'm guessing that the fd cage is too wide for the chain. thanks again for the reply sir.
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Post by flipnidaho on Mar 29, 2008 19:48:46 GMT 8
the cage would only be too wide if: 1. The original crank was a 2 ring crank and the new one is a triple. 2. The original crank was a 9 spd and the new one is a 10 spd (or 8spd to a 9 spd)...
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Post by wcoastbo on Mar 30, 2008 13:25:53 GMT 8
If the FD was shifting fine with the other crankset, then it should shift fine with the compact. My guess would be an adjustment problem. How was the shifting with the old crank installed? What exactly is the problem? -not shifting into the big ring properly? -not shifting into the small ring properly? -chain drops off when shifting to small ring? -chain drops off when shifting to big ring? -chain rubs on FD when you're in certain gears on the cog? -are there ramps and pins on the big ring? -is the FD properly aligned vs the rings? I would try to fix the problem before upgrading to a new FD or you risk having the same problem. www.parktool.com/repair/readhowto.asp?id=75
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Post by king on Mar 30, 2008 14:06:15 GMT 8
some derailleurs don't shift compact rings as well. something about the shape or the length. some of the newer ones are designed for both. fsa makes a compact specific fd as well. i have an old shimano ultegra that shifts a compact just fine though. you might want to check the specs of the avanti if it's compatible for compacts as well.
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bakalboy
XC Rider
today is the best day to ride!
Posts: 112
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Post by bakalboy on Mar 30, 2008 20:29:42 GMT 8
the cage would only be too wide if: 1. The original crank was a 2 ring crank and the new one is a triple. 2. The original crank was a 9 spd and the new one is a 10 spd (or 8spd to a 9 spd)... sir the orig crank also had 2 rings but i read a marking in the tiagra crank that it can handle a 10spd drivetrain though the new tiagra gruppo is still 9spd. thanks.
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bakalboy
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today is the best day to ride!
Posts: 112
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Post by bakalboy on Mar 30, 2008 20:52:55 GMT 8
If the FD was shifting fine with the other crankset, then it should shift fine with the compact. My guess would be an adjustment problem. How was the shifting with the old crank installed? What exactly is the problem? -not shifting into the big ring properly? -not shifting into the small ring properly? -chain drops off when shifting to small ring? -chain drops off when shifting to big ring? -chain rubs on FD when you're in certain gears on the cog? -are there ramps and pins on the big ring? -is the FD properly aligned vs the rings? I would try to fix the problem before upgrading to a new FD or you risk having the same problem. www.parktool.com/repair/readhowto.asp?id=75shifting was ok when the old crank(truvativ touro) was installed. but the old bb(68mm) has 2 3mm spacers installed. the bottom bracket shell is 73mm. i installed a tiagra crank with no spacers. from the small to the big chain ring. it will shift ok, but i have to give the shifter a good push for it to shift. had to limit the h screw as to not derrail th chain out of the big ring but i can live with it. the problem comes when i shift from the big to the small ring. the chain gets caught between the rings. have to back pedal just so the chain rails with the small ring. but back pedaling on climbs? i'm using a dura-ace chain. do a 10spd and a 9spd chain differ in width? thanks for the link sir. it was very helpful. and thanks also for the suggestions. much appreciated.
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bakalboy
XC Rider
today is the best day to ride!
Posts: 112
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Post by bakalboy on Mar 30, 2008 20:54:29 GMT 8
some derailleurs don't shift compact rings as well. something about the shape or the length. some of the newer ones are designed for both. fsa makes a compact specific fd as well. i have an old shimano ultegra that shifts a compact just fine though. you might want to check the specs of the avanti if it's compatible for compacts as well. will check it out sir. thanks for the reply.
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Post by enzo on Mar 31, 2008 15:03:36 GMT 8
brad Nesty,
yup! the 10 speed chain is narrower than the 9th.
There is no way the chain should ever get stuck in between the two rings, unless you are using the 10 spd chain or there is a thin spacer in between the rings. Which I doubt.
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Jan Atienza
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Post by Jan Atienza on Mar 31, 2008 17:37:44 GMT 8
Question Gurus - hope this is on topic
If I change my cassette from 12-25 to 11-28 while retaining the standard size chainrings, will this simulate the compact crank ratio whatchamakulit? Or do I still need to change to a compact crank?
TIA.
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Post by wcoastbo on Apr 2, 2008 5:13:44 GMT 8
I agree with enzo, and have never come across a chaing getting stuck between the big and small ring. This does not sound like a FD adjustment issue. It's possible that one of the rings was mounted the wrong way (there is a left/right, front/back). pretty obvious for the big ring, not so easy to tell for the small ring. It's possible that someone up the distribution chain swapped out the original rings for some generic ones. I'm not familiar with this crankset, but the big ring should have ramps and pins. If you have a simple SS type ring, then shift performance will be negatively affected. Can you take a closeup pic of the inside portion of you crankset, ideally with a the chain between the two rings. As king mentioned, not all FDs are great with compacts. You might have to live with it the slow shifting to the big ring.
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Post by wcoastbo on Apr 2, 2008 5:47:50 GMT 8
Question Gurus - hope this is on topic If I change my cassette from 12-25 to 11-28 while retaining the standard size chainrings, will this simulate the compact crank ratio whatchamakulit? Or do I still need to change to a compact crank? TIA. Just do the math, while holding all else constant (such as crank length). 39/28=1.39 34/25=1.36 this tells me that you new low end gear would be very close to a compact with the old cog. I doubt one could tell the difference between the two gears. 53/11=4.82 50/12=4.17 mating a compact with your current cassette would have you spinning quite a bit on fast downhill sections over 40 mph. if you don't spend a lot of time pedalling at speeds over 40 mph, not a problem. mating a new cogset with your standard crank would give you a very tall top gear, pretty useless unless you're moving at speeds over 35-40 mph. IMHO the best setup is a compact with an 11-28 (for my type of riding... touring, endurance, climbing/descending). This would give you the range close to a triple without the weight penalty or complexity. This is not the best setup for crit racing, not enough middle gears. Most tend to want ratios that are close to each other. As usual, depends on your needs and riding style.
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Jan Atienza
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Post by Jan Atienza on Apr 2, 2008 17:51:23 GMT 8
wcoastboThanks! sleepy during math eh. Anyway, wasnt sure so I just mated a compact with the 11-28...buti na lang this is what you'd eventually recommend kaya perfect for me (same style of riding as yours <touring part only>)
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bakalboy
XC Rider
today is the best day to ride!
Posts: 112
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Post by bakalboy on Apr 2, 2008 19:44:04 GMT 8
brad Nesty, yup! the 10 speed chain is narrower than the 9th. There is no way the chain should ever get stuck in between the two rings, unless you are using the 10 spd chain or there is a thin spacer in between the rings. Which I doubt. thanks sir enzo! i might be using a 10spd chain. it's not actually stuck in the middle of the rings, it just doesn't rail on the small ring. oh man, guess i have to buy a new chain. thanks again da man!
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bakalboy
XC Rider
today is the best day to ride!
Posts: 112
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Post by bakalboy on Apr 2, 2008 20:00:06 GMT 8
I agree with enzo, and have never come across a chaing getting stuck between the big and small ring. This does not sound like a FD adjustment issue. It's possible that one of the rings was mounted the wrong way (there is a left/right, front/back). pretty obvious for the big ring, not so easy to tell for the small ring. It's possible that someone up the distribution chain swapped out the original rings for some generic ones. I'm not familiar with this crankset, but the big ring should have ramps and pins. If you have a simple SS type ring, then shift performance will be negatively affected. Can you take a closeup pic of the inside portion of you crankset, ideally with a the chain between the two rings. As king mentioned, not all FDs are great with compacts. You might have to live with it the slow shifting to the big ring. whoa! have to read your answer a few times before i fully understood it ;D. sadly my camera is busted so i can't take pictures of the crank. i inspected the crank and the rings seems to be in order. the big ring is ramped while the smaller one is not. both the rings have shimano's patented marks so i think the crank's fine. i'm guessing that the fd is the culprit. saw the cage of a tiagra fd from a fellow rider's bike and it is narrower than the avanti installed in my bike. it seems that the avanti is for a triple. i will replace the fd first then post an update here. thanks for the informative answer sir wcoastbro.
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Post by wcoastbo on Apr 3, 2008 4:30:25 GMT 8
Yes, a triple FD could be a problem with a compact. lots of good info to be found on the late sheldon brown's site, one of my favorite places to visit. In case you haven't checked it out yet... sheldonbrown.com/front-derailers.htmlI'm glad you found the problem. Odd that the bike was spec'd with a triple FD to begin with. Soon, you'll be an expert mechanic as you learn from the web, sure beats the way I learned before the internet... by trial and error, mostly error ;D
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