Mountain Biking - Shimano Acera...Problems?

Hi, i'm a newbie here and i own a TREK Series 3 3900 Mountain Hardtail...

I have owned this bike for about 6 months now, it's really comfortable and it really fits me...i guess...

But i have had some problems with my gears...

This bike has 24 gears...3 on the front and 8 in the back...

Firstly, from gear 3 to gear 4, it takes about 5-10 seconds to change...

Secondly, whenever i ride and change it to gear 5, my chain doesn't want to change...

And if i press it again, it goes to gear 5...

So it means on the gear shifter thing (the thing that tells you what gear you're in), it says '6', but on the chain it is gear 5.

Also for this reason, i cannot get to gear 8 easily either. I have to go to gear 6, and then quickly double click the gear shifter and then just hope it jumps the 7 and hits the 8...

I have tried to oil the gears...but that doesn't help...

Any ideas??

PS : I'm a truee newbie...and oh yeah...i do leisure XC. =)

It could be dirt build up in the cable housing.If it's not a solid housing back to the RD you can put the chain on the largest cog in the back and without pedaling shift all the way down with the shifter. This will throw slack in the cable. Take the cable housings loose and slid them up and down the cable.Use some light weight lube while doing this(rock and roll works great).Use a clean rag to wips any junk off the cable.Put the cable housing back in place and see if this helps your problem.

Thanks for the quick reply.

but im not sure if it's the problem with the cable, because once i shift the gear, the (derrailleur?? i think...) moves, but probably not enough to move the chain down...

anyways...i still dunt get this...

"If it's not a solid housing back to the RD you can put the chain on the largest cog in the back and without pedaling shift all the way down with the shift"

Is the largest cog gear 1??

and i really dunt understand the "without pedaling shift all the way down with the shift"...

im sorry, but im really new at this...

=(...

It sounds like it is just out of adjustment. If it was a new bike you bought and you haven't had it adjusted then that is most likely the issue.

Cables stretch and parts wear in and need to be adjusted to compensate for this. I usually get a full tune up on mine at the beginning of Spring and it is good until the following spring as I don't ride inthe winter. If you ride a lot more then you may need to make adjustments a little more often.

There are some good online sources that can walk you through how to do this or you can take it to your LBS and have it done. I usually take our to the LBS as they do a great job, work through everything that needs to be done and do it for a great price. After a good thorough tune up it is almost like riding a new bike again.

Shift to gear 1, and make sure the derailleur actually moves there.

Push the button to shift it to gear 8, but don't let it actually move at all in the rear. That should put some slack in the cable so that you can lube it.

Shift to gear 1, and make sure the derailleur actually moves there.

Push the button to shift it to gear 8, but don't let it actually move at all in the rear. That should put some slack in the cable so that you can lube it.

...at least someone got it.

thanks for the really quick replies...!! really appreciate it!!

anyways...

i get it!!

so when your bike is stationary, you shift the gear, allow the derailleur to move, but not the chain, rite? so that will cause the cable to be kinda lose, then lube it...rite?

so...what lube can i use?

i mean like, is there a special lube for this?

and thanks for the idea rallykid, if the lubing doesn't work, i'll head straight to my LBS!!

oh yeah, and btw, the next time im going to my LBS im gonna check out what disc brakes and seat suspension posts they have. and maybe also front suspensions...coz my TREK 3900 is not the disc version, my LBS didn't have 'em. =(

that was off-topic...

haha =)

I use tri-flow. I believe it can be gotten from a hardware store for cheaper then a bike store.

Check guides for how to adjust your derailleur, chances are there's been a lot of cable stretch and it needs a little work on top of the cable being lubed.

Only shift gears without peddling if the cable loosens, if you shift to a larger sized gear when not peddling the cable, shifter, chain, or casset can break from the force applied.

http://sheldonbrown.com/derailer-adjustment.html Look around his sight for more help and general knowledge.
Sheldon is a legend.

thanks!!

again...

ok sry, but another off-topic question...=)

if i add disc brakes, will there be stress on the bike frame??

because the stress of the frame might shift places causing the frame to...split

also the same question with changing my suspension, mine rite now is a SR SUNTOUR XCT-V2, with 80mm travel and preload adjustable (whats preload adjustable?? i dunt know...please tell me...).

http://sheldonbrown.com/derailer-adjustment.html Look around his sight for more help and general knowledge.
Sheldon is a legend.

ooo....thanks!!

Disc brakes..That's a job, and pricey.
Unless your frame has mounts, they'd need to be added, which is expensive.
You'll need a front fork with the mounts, you'll also need front and rear hubs.
If your bike has all that, great, if not...:eek:
It adds a lot of stress to your wheel, I think mainly just the hub, don't quote me on that.

Get some Kool Stop pads, the salmon color if you're planning on riding in the wet, or are worried about puddles causing your brakes not to work for the first few seconds. Dry stopping power is comparable to regular brakes, maybe slightly less grippy.
I've noticed hardly any wear on mine in 200 miles, I'm a big guy (250lbs, 6'9") and normally tow ~80lbs in kids and gear, so they should last an average person a good long time.

LBS's get them for about the same price as online, and they'd be sure to get ones that work for the style of brakes you have, so it's worth the $1-2 extra.

Thanks for the Kool Stop tip...i might get those if i really cant add disc brakes to my bike...

so anyways...

about how much are average hydraulic disc brakes?

coz, my front fork is V-brake and Disc Brake compatible...not sure about my hubs...or my rear mounts...

i'll go and check it at my LBS...

sorry to quote you on the hub stress part, but if it does add stress, what would happen?

I've really no idea on the details on disc sets, I looked up what it'd take to convert mine, was on the order of a new frame, fork, wheels, blah blah... Stopped there.
I vaguely remember something about it putting more force on the spokes/hub since it was having to stop the bike so close to the axle. Like smaller gears require more force to use.. Ya might want to google it, or wait for someone who knows what they're talking about. I'm guessing if you don't use stronger wheel sets they could break in some form.

I'm not sure on the cost for parts either, or if hyd. disc brakes are better then cable in real world usage.

Research never hurts :p

haha

i guess i'll wait for someone...to drop by..say hi...give some help...haha

anyways...i checked it on Wikipedia (=D!!) "Types of bicycle brakes" Under "Disc Brakes" and "Disadvantages".

here's the link...you might wanna check it out...maybe...

http://en.wikipedia.org/wiki/Bicycle_brake_systems

it does talk about the spokes...and the other stuff you might want to know....

=)

Thanks for the Kool Stop tip...i might get those if i really cant add disc brakes to my bike...

so anyways...

about how much are average hydraulic disc brakes?

coz, my front fork is V-brake and Disc Brake compatible...not sure about my hubs...or my rear mounts...

i'll go and check it at my LBS...

sorry to quote you on the hub stress part, but if it does add stress, what would happen?

For a cheap set (Hayes 9's) you'd be looking at $80 online on closeout per wheel for the brakes themselves.

If you see holes on the left side of the rear dropout, than the frame is disc compatible.

If the hub has rotor mounts on the first place, it is designed with disc brakes in mind and you don't have the worry about it.

It sounds like it is just out of adjustment. If it was a new bike you bought and you haven't had it adjusted then that is most likely the issue.

Cables stretch...........


I use tri-flow. I believe it can be gotten from a hardware store for cheaper then a bike store.

Check guides for how to adjust your derailleur, chances are there's been a lot of cable stretch........

Do cables really stretch?

FYI: Talk to Cheeto, but I don't think that the 3900 has disc mounts.

Do cables really stretch?

Either the cable stretches or the housing is squeezed smaller, I'm not entirely sure. Either way, the cable needs the slack removed over time.

Do cables really stretch?

Oh hoho!

I see wut ur tryin 2 do. Itsa trap!

Thanks again!! Everyone...

I checked on www.trekbikes.com...

http://www.trekbikes.com/us/en/bikes/mountain_hardtail/3_series/3900disc/

this is the 3900 Disc version...

http://www.trekbikes.com/us/en/bikes/mountain_hardtail/3_series/3900/

and this is the 3900 normal version, mine.

the only difference is that the 3900 Disc version has Shimano M475 rear hub...

and the normal 3900 has Shimano RM30 rear hub...

and of course a different brakeset. it might be the different hubs...im checking...

oh oh oh!! the frame on both the 3900 and 3900 Disc version says it has disc brake compatible dropouts...thats better...i feel better already!!

=)

haha

Sounds like you just need to spend some time getting to know how to adjust your front and rear derails.

Go to this site, which has tech docs for Acera series products:
http://techdocs.shimano.com/techdocs/blevel.jsp?JSESSIONID=LGqWq1KcBThZ1xtKLswjqqgGpWvGLPwNVFvDv5pVKhQnqn1jLhdz!-1442252462&ASSORTMENT%3C%3East_id=1408474395181679&FOLDER%3C%3Efolder_id=2534374302051137&bmUID=1220963030748 (http://techdocs.shimano.com/techdocs/blevel.jsp?JSESSIONID=LGqWq1KcBThZ1xtKLswjqqgGpWvGLPwNVFvDv5pVKhQnqn1jLhdz%21-1442252462&ASSORTMENT%3C%3East_id=1408474395181679&FOLDER%3C%3Efolder_id=2534374302051137&bmUID=1220963030748)
You can download PDF files which have detailed instructions on how to adjust and troubleshoot you components.

IMHO, you should be aware that the Acera is very entry level stuff, and for not much $$$$, you can upgrade to much better quality derails down the road.

awww man!!

the Shimano RM30 rear hub...the one on my 3900...isn't disc brake compatible!!

thanks Alpha52!! i'll keep that in mind...=)

btw i checked my 3900 and the 3900 Disc Version, all Geometries are exactly the same, which means, with or without disc, my bike frame can support it. =) yay!! lol (ppsstt...bear with me, im young...!! like 13 yrs old...=D)

but im not sure, will it be worth to get another rear hub just for the disc brakes?

i checked the Shimano M475 rear hub and it's like $23 (USD)...

btw im live in Bangkok, Thailand but im not a Thai...=) so some items that you guys mentioned...i might not be able to get them...easily...

anyways...going to my LBS tmr w/o my bike just to check out what they have...

i'm planing to get disc brakes in the front but not the back, for two reasons...

1st : My fork allows disc brakes
2nd : Brakes should be more concentrated on the front...rite?

and for my rear brakes, i'm just keeping my Tektro V-brakes but probably get Kool Stop or other pads just for better braking.

=)

will post back when get back from shop tmr with what they have.

I'll need opinions!! and Facts too!!

=)

*sighs*

and so my LBS doesn't have Kool Stop pads or any other pads...and they say seat post suspension is bad for my bike, and i cant get just one disc brake. they sell in packs of 2...and so i asked if i could just change the rear hub, they said no. They also sell only in packs of 2. About 3K THB for the hubs, and about 5K THB for the disc brakes...

also together 8K+- and thats the price i bought my TREK 3900!! (i know...i bought it off REAL CHEAP...)

grrrr....so pissed...i asked them if they had Specialized Hardrock...she said no...but in Novemeber 2008, they said a whole load of Specialized bikes with come...dunno what to do...ARGH!!

and they said some MERIDAs are also coming 20th this month...

do you guys think MERIDA is good? the MERIDAs that are about $500...or should i wait...or just get the disc brake and hubs that is 100% the price of my bike??

need assistance...*sighs*

My advice? Just ride the bike. Put better V brake pads on it if you need them. If you don't need them, don't worry about it. Disc brakes are good, but a good set of V's tuned right works fine in just about any circumstance I've ever encountered.

Don't get hung up thinking that you need discs, a new wheelset, new fork, or whatever else upgraditis tells you you should have- they might be nice, but you don't actually NEED them to enjoy riding.

So yeah, just enjoy riding the thing. :)

Thanks!!

that sure woke me up.

seriously! upgraditis has been affecting me since lots of people say my bike s*cks...(it actually does)

i've not ridden any trails...only urban riding around my neighborhood...

anyways...i'll go see my neighbor...ask him a few things about trails...around where i live...need to go there...see it...see what i REALLY need on my bike.

thanks Diomedes!!

=)

THREAD CLOSED. =D

haha