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Is my front derailleur bent?

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Post: #1
Is my front derailleur bent?
Hi all. I'm new to repairing my bike myself, but I got so fed up with the dishonest or incompetent shops in the area that I've decided to just do things myself. So far all I've done are change a flat tire (and install rim tape and wheel liner while doing that) and just now I replaced a gear shift cable.

anyway the background to my question is as follows. A couple months ago one of my pedals broke off. Although I had already started fixing some stuff myself, I brought it to a shop to fix as I didn't have a pedal laying around, not expecting that to break, and I need my bike, I ride it a lot. The guy at the shop said he couldnt get the pedals off and needed to replace the crankset. ($75) Ok, fine, gotta do what I gotta do, I need my bike.

When i picked it up, I noticed that the chain sounded like it was rubbing against something or something, (yes, very technical Wink ) but I didn't think much of it, not knowing what might be wrong. After a time, I think because the chain kept slipping, i tried shifting gears to see if it was misaligned. instead of shifting, though, the cable broke. i figured i would just change it myself, but i only recently got around to getting one and trying to do it. when i went to do it, however, i discovered why it broke: the derailleur doesnt fit over the larger gear, making it unable to move more than a little bit. since the calbe was a bit older, it broke.

i took the bike back to the guy and said the he put the wrong size crankset on. he said that once he finished his lunch (he happened to be eating when i came in) he would take a look at it. once he finally did, he said that the derailleur is bent and needs to be replaced, and thats why it doesnt fit, not that the crankset is too big.

so, the question is, is this true? it looks the same to me as it always did, and i never had this problem before. its an older bike, so im guessing its possible that standard crankset sizes have changed, or maybe theyre different between mountain bikes and road bikes. (this is a road bike.)


some pics of the derailleur: (if you need a different angle, let me know, ill try to get it.)

[Image: IMG_4763_zps07093557.jpg]

[Image: IMG_4762_zpsee06eb67.jpg]

[Image: IMG_4761_zpsf4389424.jpg]


thanks for the help.

-RF
Apr 8, 2013 04:39 PM
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nfmisso Offline
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Post: #2
RE: Is my front derailleur bent?
RF;

Looks like the FD is rotated around the seat post and too low.

$75- for a $35- crank set !!!

Your bike needs a LOT of TLC. What is your budget? If you are close to one of us, we could probably help.

At this stage, I would just remove the front derailleur, or lock it in place with the limit screws over the smaller (or middle if a triple) chainring, and remove the cable.

Nigel
Apr 9, 2013 08:08 AM
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1FJEF Offline
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Post: #3
RE: Is my front derailleur bent?
And oil & check the chain for stretch.
Apr 9, 2013 12:10 PM
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RE: Is my front derailleur bent?
(Apr 9, 2013 08:08 AM)nfmisso Wrote:  RF;

Looks like the FD is rotated around the seat post and too low.

$75- for a $35- crank set !!!

Your bike needs a LOT of TLC. What is your budget? If you are close to one of us, we could probably help.

At this stage, I would just remove the front derailleur, or lock it in place with the limit screws over the smaller (or middle if a triple) chainring, and remove the cable.

thanks for the reply.

rotated around? you mean a little bit or that it should be on the other side? i think the rotation is good, it lines up with the gears, it just cant pass over them. (i probably should have mentioned that in these pics, the chain had fallen off and i hadnt replaced it yet, and it still has a piece of the old broken gear cable hanging down, probably making the cable look funny.)

the guy at the LBS said that its bent becasue it should be conforming more to the curve of the gear, rather than being far away in the front of it and too close in the back. he did show me on some bikes that they were like that, but those were mountain bikes. when i searched for road bike front derailleurs online, they looked more like this, though it was hard to tell since the pics werent of it actually on a bike.


i had a feeling it was overpriced, but i was in a pinch. no wonder he's so lazy, though. when you gouge people that badly, you only need to do a job or two per day to make a living.


yeah, theres a few other problems with the bike as well, although its in pretty good condition overall. the biggest other thing is one of the brakes got messed up trying to get my bike out from under some idiot who locked up his next to mine, but luckily not through mine. (he actually did that twice... :o ) the brake works, but only with the lower handle, not the upper one, that one cant apply enough pressure anymore, it mustve gotten caught on something. im in brooklyn, ny, if anyones nearby.


i thought about just moving the derailleur up, but then the chain would be pulled up by it and constantly rubbing against it rather than just sliding through it. although i suppose its rubbing a bit now, anyway. now that i replaced the cable, i have it positioned as close to over the smaller gear as possible. it still slips a little now and then, but its much better than before when it was off to the side a bit and kept falling off whenever i hit a biggish bump or pedaled too hard. should i just move it up so that it can move freely? (assuming it doesnt need to be replaced.)

thanks again.
Apr 9, 2013 05:56 PM
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nfmisso Offline
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Post: #5
RE: Is my front derailleur bent?
Yes, move it up. You will probably have to release the cable to the FD before you can move it up.

Nigel
Apr 9, 2013 06:25 PM
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DaveM Offline
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Post: #6
RE: Is my front derailleur bent?
The derailleur is bent. The curve at the bottom of it should roughly follow the curve of the chainrings.
You could try moving it up a little so it doesn't hit the chainrings though you might have trouble with the chain rubbing on it.

I think your best options are either to remove it and just have the bike stay in one gear in the front or buy a replacement ($15 part or so, but you may need a couple tools, like a chain breaker to install it yourself.)

And put some oil on your chain...seriously Smile
Apr 10, 2013 08:54 AM
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nfmisso Offline
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Post: #7
RE: Is my front derailleur bent?
The other problem your are running into is that the Shimano Altus is a MTB group, not a road group.
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/ALTUS/SI_6NMFA_001/SI_6NMFA_001_En_v1_m56577569830621467.pdf
The Altus FD is good for 48T chainrings MAX, and some versions are 42T max.

If you replace it; get one of these:
http://www.amazon.com/Shimano-FD2300-Front-Derailleur-Braze-On/dp/B002UZFRMO/

Nigel
Apr 10, 2013 11:56 AM
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Joe_W Offline
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Post: #8
RE: Is my front derailleur bent?
Careful, there is a "braze on" version and one with a clamp. You can also get last-or-before-years FD in higher quality for that money or less. I think I paid about 10 EUR (15 USD?) for a Shimano 105 two years ago (of... dunno, yesteryear's group, or that one before... or older?). Shop around, Amazon is not the only source of bike parts. (well, I don't know about the US, I have to admit).
Apr 11, 2013 06:43 AM
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RE: Is my front derailleur bent?
(Apr 10, 2013 11:56 AM)nfmisso Wrote:  The other problem your are running into is that the Shimano Altus is a MTB group, not a road group.
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/ALTUS/SI_6NMFA_001/SI_6NMFA_001_En_v1_m56577569830621467.pdf
The Altus FD is good for 48T chainrings MAX, and some versions are 42T max.

If you replace it; get one of these:
http://www.amazon.com/Shimano-FD2300-Front-Derailleur-Braze-On/dp/B002UZFRMO/

i need a chain breaker first before i remove or replace it. i ordered one, but its coming from hong kong, so its gonna take a while. ill see what i do when that comes. for now ill try moving it up and see how that goes. if i do replace it, theres two options for the one you recommended, the braze on or the other. whats the difference and which would i need?

oh, i just had an idea. if i move it up, the chain will probably rub on the bottom of the derailleur. i bet i could put a plastic ring on it so that it spins that instead of rubbing the derailleur. now i just gotta find one.


(Apr 10, 2013 08:54 AM)DaveM Wrote:  The derailleur is bent. The curve at the bottom of it should roughly follow the curve of the chainrings.
You could try moving it up a little so it doesn't hit the chainrings though you might have trouble with the chain rubbing on it.

I think your best options are either to remove it and just have the bike stay in one gear in the front or buy a replacement ($15 part or so, but you may need a couple tools, like a chain breaker to install it yourself.)

And put some oil on your chain...seriously Smile

what kind of oil is best? would wd-40 work?
Apr 14, 2013 10:04 AM
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Joe_W Offline
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RE: Is my front derailleur bent?
WD 40 is no oil do not use it on the chain, it will very definitely ruin it!

http://bicycletutor.com/no-wd40-bike-chain/

WD40 can be used as a penetrating agent when bolts have corroded in place. It will flush out any lube from the chain and leave a very sticky residue that attracts dirt like crazy.
Apr 14, 2013 11:05 AM
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RE: Is my front derailleur bent?
oh, great. now my axle broke while riding the other day. i thought the wheel just got misaligned but i redid it and it still messed up when i tried it out. i took off the wheel and the axle was in two pieces. im guessing thats not supposed to be like that... Wink is there much variance in axles that i need to be aware of in buying a new one or will pretty much any one fit?
Apr 14, 2013 11:33 AM
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Joe_W Offline
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RE: Is my front derailleur bent?
Ouch. Axle replacement is... tricky. While it in principle can be done I belive it is usually hard to find the parts. Good luck!
Apr 14, 2013 12:55 PM
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nfmisso Offline
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Post: #13
RE: Is my front derailleur bent?
FD:
*. you need a clamp on FD; not braze on.
*. measure the diameter of the seat tube (where the FD clamps on to the seat tube). Most likely it will be 28.6mm
*. in the Amazon link I posted above, you will see a size tab with some choice, one of those must match the diameter of seat tube, OR by adding a shim, match that diameter. I have gotten several FD for 34.9mm the used a shim made of 1/8" wall, 1¼" OD aluminum tube, cut to length and split in half lengthwise. Often the 34.9mm FD are cheaper on ebay, but you have to be able to come up with a shim of the correct dimensions.
*. you need a FD that has a maximum chainring capacity bigger than the biggest chainring that you are using. (hint: not MTB FD).

Axle:
*. front or rear ?
*. metric or English thread? Metric is M10 x 1; English is probably 3/8"x24tpi or 3/8"x26tpi
*. pictures ?
*. can you get the bearing cones and all the hardware off your present axle?
*. lots of choices on Amazon; search for rear axle in cycling:
http://www.amazon.com/s/ref=nb_sb_sabc?url=search-alias%3Dsporting&pageMinusResults=1&suo=1365972092567#/ref=sr_nr_n_0?rh=n%3A3375251%2Ck%3Arear+axle%2Cn%3A%213375301%2Cn%3A3403201&bbn=3375301&keywords=rear+axle&ie=UTF8&qid=1365972101&rnid=3375301
*. your bearing balls are shot; need new ones.
*. good chance that the bearing surfaces in the hub are shot - requiring a new hub.
*. I would replace the hub and spokes and rim - I build my own.
(Apr 14, 2013 12:55 PM)Joe_W Wrote:  Ouch. Axle replacement is... tricky. While it in principle can be done I belive it is usually hard to find the parts. Good luck!
easy to find the parts if you know what you have to find (metric, English, length, thread pitch, etc) on Amazon. Hardest part is figuring out what you need.

But likely the bearing surfaces inside the hub are shot - which means a new hub.

Nigel
Apr 14, 2013 01:45 PM
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RE: Is my front derailleur bent?
ok, so, thankfully i was able to fix the axle. i walked about 1/2 hour over to a lbs ive never been to before with the broken one and got a new one. i think it wasnt quite the right thing, as some of the piece that touches the bearings didnt fit into the wheel, just onto it, but i was able to use the ones from the old one and fix it. took it out for a quick spin, and it seems to be riding fine, other than the chain rubbing on the derailleur since i moved it up. im gonna try rigging something for it to spin on instead of just rubbing, but it that doesnt work ill try to take it off for now as i just noticed that it looks like theres a screw at the bottom of it holding it together, so i might be able to get it off without a chainbreaker. my only concern with that is the chain falling off as the rear gear i usually ride on is off to the side from the smaller front gear. before i replaced the cable when the derailleur was off to the side, it kept falling off and im worried that might happen with no derailleur. do you think it will?

(Apr 14, 2013 01:45 PM)nfmisso Wrote:  FD:
*. you need a clamp on FD; not braze on.
*. measure the diameter of the seat tube (where the FD clamps on to the seat tube). Most likely it will be 28.6mm
*. in the Amazon link I posted above, you will see a size tab with some choice, one of those must match the diameter of seat tube, OR by adding a shim, match that diameter. I have gotten several FD for 34.9mm the used a shim made of 1/8" wall, 1¼" OD aluminum tube, cut to length and split in half lengthwise. Often the 34.9mm FD are cheaper on ebay, but you have to be able to come up with a shim of the correct dimensions.
*. you need a FD that has a maximum chainring capacity bigger than the biggest chainring that you are using. (hint: not MTB FD).

i measured the seatpost, and without getting exact with calipers, it looks like its about 28.6 mm. will the one you linked before work, then? the larger chainring is 52 teeth.

thanks again for the help.
Apr 14, 2013 06:14 PM
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nfmisso Offline
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RE: Is my front derailleur bent?
chain coming off without a FD - can happen, especially if there is a lot of chain angle.

The Shimano FD-2300 http://www.amazon.com/Shimano-FD2300-Front-Derailleur-Braze-On/dp/B002UZFRMO/ will work - IMPORTANT - make sure you use the Size drop down menu and pick "28.6/31.8" and not "Braze-On" This FD is for a double, which is what I see in the pictures. If you had a triple, you would need a FD-2303: http://www.amazon.com/Shimano-FD-2303-3x8sp-F-derailleur-31-8mm/dp/B002UZBSSG/

The FD-2300 (and 2303) are made to fit 31.8mm seat posts, and include a shim to fit 28.6mm

My Miyata 310, when I finish it will have FD-2300 and RD-2300. http://forums.bicycletutor.com/thread-3598.html
It is on hold for a couple of months, as we're moving, to a house that will have a new 640sq ft garage soon - new garage is in the permitting process now.

Nigel
Apr 14, 2013 06:47 PM
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RE: Is my front derailleur bent?
hmm, its rubbing pretty bad, even after trying to rig something to smooth it. maybe ill just move it back down for now, it seemed ok like that, i just couldnt shift higher. it sounds like a machine gun right now. that cant be good for the chain...
Apr 14, 2013 07:15 PM
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RE: Is my front derailleur bent?
for now, i took off the cable, lowered the derailleur and rotated it slightly so that its as close to the proper position as possible. still rubbing a bit but its all i can do until the new derailleur and chain breaker come.
Apr 15, 2013 08:48 PM
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haykong Offline
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RE: Is my front derailleur bent?
First question that need to be asked is what bike you have? You say it's an old road bike right? Has the bike been painted over? Is there a brand name written on it and model? Does it have drop bars or does it have bars like an upright right bike?

The reasons why I ask these questions is the tires you have on look like some kind of hybrid bike or cx bike plus you have an atlus deraileur which is a mountain groupset. Assuming the Altus front dérailleur is original then your original crankset should also probably be part of that groupset or at least a hybrid cranket with a max 48t..

For example miyata triple-cross late 1980s early 1990s was a hybrid upright road bike with mountain bike groupset

Question is what cranket did the bikeshop replace the original one with??? There is where the problem starts especially if the bikeshop guy does not know enough especially working with non-modern bikes. Besides his first guess before he actually looked at it is he put on the wrong cranket size and then he blames the derailleur because of a cranket mismatch. I can't say the derailleur is bent looking at the photos but I can say if the replacement cranket top ring is a 52 teeth or 50 teeth size then it is more likely a crankset mismatch to the front deraileur since the max teeth it can handle is normally 48 teeth which is why it does not curve to a road cranket of 52/50 teeth.

Here is another thing to consider which the bikeshop guy did not think about which no one has yet mentioned on this post, the bottom bracket spindle length which will also be another mismatch especially if the bikeshop guy put a road cranket which requires a shorter spindle length than say shimano mountain crankset which sometimes uses a 122.5mm spindle length. Squared taped spindle lengths bottom brackets come in many sizes which affect the chainline of cranket.


If I were you I would go back the the bikeshop guy asking for the old part so you can look up the part number and see what spindle length you have or you would have to take apart the bottom bracket and determine the spindle length. Sheldon Brown's website has information on older crankets and bottom brackets.

Anyway at point, I'm pretty sure it is a crankset mismatch..... Question was your original crankset a double or triple ring?

At this point it seems the bikeshop guy does not know enough..... At least demand a refund..

If you want to replace it yourself, I can help you through it... At least you replaced your rear axle which says that you have the skills to do it. You just need the tools and knowledge.

Just less than 4 years ago I started riding bikes again and started my voyage in repairing bikes for friends and family. Found older bike shop quality bikes on Craigslist cheap and rebuilt them up for friends and family. Bicycle tutor website was very helpful when I began my basic repairs back in the day when the website was free but filled with ads in the video. As I out grown the website, I found that's sheldon brown's website had more info on older parts and stuff which was more useful and technical.


At this point, changing your front derailleur won't help you too much since botom bracket spindle length is also another issue. After re-reading your posts saying that the chain still slips off the small front gear when your just riding might suggest that your chainline is way off and the crankset is sticking out way too far because of long spindle length ... Do me a favor look at your crankset both sides and see if you can find a brand name and model number so we can determined that spindle length that replacement crankset requires.


Also I have another question for you..... How many gears do you have on the rear wheel? 5/6/7?

If your original crankset was 48t.. Jumping to 52t requires a longer chain.

Also have you checked for chain stretch using a park tool? This checks for chain wear.

Let me know if you still want help

Ok after re-reading sounds like you have a road bike with dropbars that have the crappy dual levers that don't work well from the tops. Question do you have cantilever brakes or sidepull brakes... So also is your rear dérailleur an Altus ? Trying to determined what is original or not....
Apr 17, 2013 04:12 AM
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nfmisso Offline
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Post: #19
RE: Is my front derailleur bent?
Please do not let Haykong's post confuse, most of it is not applicable.

It does not matter what your bike started out as, what matters is what is it now, and what do you want it to be.

Below are various details that may or may not be valuable to the specific situation.

Chainline is over rated; with 7 and more cogs at the rear, the chainline can be off ± 5mm with minimal effect.

Lots of us, especially on tandems, commuting and urban bikes mix components intended for road and mountain bikes.

Front derailleurs have a lot of travel, it is extremely rare that one will get out of range. Tandems typically use road triple FDs with extra long bottom brackets to work with the wide to very wide rear hubs and large chain rings. For example, our tandem has a 54 tooth large chain ring (44T middle and 26T granny bailout ring) on a 130mm BB. The rear hub is 140mm OLD. New road bikes have 130mm OLD; new MTB and Hybrids have 135mm OLD; new tandems are 145mm and 160mm OLD.

BB length - manufacturers recommendations are often not what works best. Nowadays, most seem to be spec'd to have no chain interference when in the smallest front cog and smallest rear cog; resulting in the chain rings being too far out for smoothest operation in the middle gears with each chain ring.

Nigel
Apr 17, 2013 08:15 AM
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haykong Offline
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Post: #20
RE: Is my front derailleur bent?
Hi Nigel,

I never said you needed to know the brand of the bike. It is not necessary to know the brand of the bike which is true, but it's nice to know and find out the history of the bike and what it is equipped with. It's nice to know that information for myself since hey I'm a history nut and like to see how the bike has changed from its original setup.

And as for chainline +/-5 chainline is ok, but when it is greater can affect. Let take an example say sugino impell 150x 48/38/28 which takes a spindle of 103mm and you stick it on it on a 122.5 spindle ...that would stick really way out... I'm just saying it is nice to know what spindle size your working with so you are with in reasonable specs.

Are you saying I'm giving bad advice?

I may ask for more information from a person in order to trouble shoot problems and sometimes information that might not seem necessary, but hey I trouble shoot IT computer problems for a living and like to cover all the different angles that others do not see. I even fix my own cars and family cars where some other car mechanics would dismiss a car problem might be a bad engine problem and turns out that it was not. So what's the harm in covering different possible angles? And I'm also a wedding photographers that covers other angles others do not see. It's also my job to make it pretty too, not your ordinary photographer.
Apr 17, 2013 09:00 AM
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