Replacing Crank Set or Chain Ring.

[Anil Bhambhani]

Dear All

I use a BTWIN Rockrider 8.1 with Shimano Deore M590 22x32x44 crankset.

I had difficulty in running F2 with R1,2,3,4.

Any time I engaged these combinations the chain would slip from F2 to F1. However I could I could run F3 and R1 without any problems. This prompted me to take a closer look at the Chain rings. Closer scrutiny showed that some of the teeth of the second chain ring seem to have worn off. The length and shape of the teeth on second chain ring seems to be different as compared to other two rings. I am attaching a couple of pictures of the second chain ring. Also the chain is not tracking straight when on the second chain ring; during every revolution of the crank at a particular position the chain shifts to inside.

I have discussed the same with Decathlon and they have advised to change the complete crankset.

Please advise if the diagnosis is correct.

Also is it possible to change only the Second Chain Ring. If yes where do I source it from, does anybody in Bangalore or Delhi stock these. Aliexpress has a lot of compatible ones and they can be shipped to Bangalore.

If I need to import the complete Crankset. Which are the other Cycling websites who do international shipping?

Any experience in using Chain Reaction or Wiggles. Both these have the Crankset for about $70. Shipping and customs would be additional.

http://www.chainreactioncycles.com/in/en/shimano-deore-m590-9-speed-triple-chainset/rp-prod40496

 

Thanks in advance to all for the help.

 

Anil Bhambhani

 

[Opendro]

There are two things you can try before you decide to change:

Assuming your FD is straight parallel to the frame plane of the bike,

1) Adjust cable tension such that it will not slip from F2 to F1. While doing so, you also need to ensure that shifting from F3 to F1 goes well. F3 will anyway have limiter and it will not fall off. Always try the shifting front while keeping rear at 4.

2) If adjusting cable tension for F2 caused shifting from F3 to F2 not working, that means we tensed up the cable too much to fix F2. This can only be caused by a wrong indexing. Assuming that your shifter is fine and pulling only a fixed amount of cable, the only other place where this index could be affected is how you have attached the bottom end of the cable. Make sure that it stays well on the groove that is designed to keep the cable secured. Any deviation from there will affect the indexing.

[Shankar Shastry]

You do not need to change the whole crankset. Just get new chain rings if the crank arms are fine. It should cost you a fraction of the cost of a whole new crankset

--
biking conversations on the world famous "Bangalore Bikers Club" :)
 
are you a part of the bicycle racing scene?
Visit www.bangalorebicyclechampionships.com for more details
---
You received this message because you are subscribed to the Google Groups "Bangalore Bikers Club" group.
To unsubscribe from this group and stop receiving emails from it, send an email to bangalore-bike...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[J]

Where do you source them? Most of them are selling crankset instead of chain rings.

I was in similar situation months back but believe me if slips under huge pressure/high cadence mostly your cranks /cassettes are worn. Do you clean and replace the chain at regular intervals? From what I heard is a cassette is supposed to last for 6k to 9k kms and cranks are at 20 to 30k range but your chains will be anywhere between 1k to 3k.

One hack to reduce cassette wear and so the crank wear is to swap chains every 300 kms with new chain such that all the cassette won't be bite by the worn off chain over and again. Buy three chains and shuffle them for every 300 kms by this you would be saving cassette and so the chain is supposed to last much longer. I'm testing this now so not much of post experience.

[Opendro]

Similar experience! We don't get chain rings for MTB. But we do get for road bikes. The only difference is the BCD, I suppose. So, if you are okay to put road bike chain rings onto an MTB, it should just be fine. But I also found that road bike chain rings are costlier than MTB crank set itself!!! So, this makes the exercise futile.

Hold on a second. If a chain ring is worn out, it won't skip to another ring. It will rather slip over, which is very unlikely scenario considering the middle ring is usually large enough.

It is just a matter of tuning. You should be able to get it working without any replacement. I'm willing to take it as a challenge if you are willing to come over to my home over the weekend :-) This is assuming that the shifter is still fine.

[Prashanth Chengi]

I'd agree with Open's feeling that it's not due to a worn out chain ring. I've seen worse wear, without skips. Must be an indexing and/or shifter issue.  The chain ring could also be bent (due to pressure applied when chain stuck between rings? )

/Prashanth

[Anil Bhambhani]

Hi All

To add to the information already posted.

The chain and the cassette have already been changed. Also Decathlon felt that the rear shifter was not retaining tension hence both the front and rear shifters also have been changed. Originally the cycle was equipped with SRAM X7 shifters and Derailleurs; since replacement for these were not available with Decathlon they changed the Shifters to Shimano Acera 9 speed. The rear derailleur was also changed to Shimano Acera however the front Derailleur is still SRAM. So its a small mess may be.

The slippage is under normal usage on any climb. If the F2 is used with R 4,3,2,1 the chain would fall inside from F2 to F1 and when you pick it up using the shifter it will go straight from F1 to F3 as that's what the shifter and derailleur positions are.

I suppose I need to start from scratch by putting the original shifters and rear derailleur and check again. Is their any maintenance or servicing that can be done on the shifters to remove the doubt that the shifter is the cause.

My bike usage has been about 10000 kms and for the first time I am changing components. 

Opendra - Thanks for the offer if I am unable to make any progress I will take up your offer. 

Regards and Thanks to all

Anil

[J]

If its 10k and you're changing for the first time, it lasted well. Mine was grinded at 6k before I swapped the entire drivetrain. Costly mistake but worth the lesson learnt.
Remember the new chain may/should not slip but if it slips then you need to change cranks too.

Nothing is mess with your setup. You may not need new shifters or derailleurs pretty soon.Mostly the cable play would also create such a mess.

If I were you, I would

1. Check my cable tuning using part tool tutorial for both front and rear
2. Will not when does the chain skips on what cogs and will introspect are they my favorite cogs
3. if no, check cable play. Gunk is the enemy. Swap new cables and they should be perfect most time.
4. if yes, ask BOTS to measure chain and cassette wear
5. Will change chain and see if cassette is fine
6. Still slips? Will change cassette and would see cranks are fine
7. Cranks slips? Will change cranks.

Usaully Shimano or SRAM have pretty good springs and they dont give just easily. But most of the time you get robbed if you're not aware about the process of checking the slippage.

You may \maintain a log and check chain wear say every 300 kms before they eat everything.

Chain - Measure wear using ruler
3 Chains to 4 Chains - Change  Cassette  or the moment the new chain slips in the new Cassette
3 Cassette - Change Cranks or the moment the new chain slips in the new chain ring

[Anil Bhambhani]

Based on all the advise.I think I will revert my bike to all the original components. From their on try changing each component at a time, will also change the cables if they are suspect. Since my skill at tuning the drive train is limited, plan to get it done at BOTS. Will post my final experience. 

Thanks to all

[J]

Try Wheelsports and Crankmeister too. You're supposed to posses little knowledege obtained from forums/parktool on bikes if you ride so much. Don't end up with something you don't know and you dont want,Trust it makes you to feel better and does wonder when you understand your bike completely.

[Anil Bhambhani]

Hi All

An update on resolution of problems with my drive train. After getting the wheel rebuild at BOTS I reverted to my original shifters and Derailleurs which were SRAM X7. Both shifter cables were changed.

The problems with the chain slipping off from F2 to F1 while using R 1 to 4 were resolved. I can use all the gears now without any restriction. So no change of Chain Ring or the Crank.The problem was I suppose with the indexing.

On the rear I still have issues with the R 8 and 9, the changeover is delayed on both up and down. Sometimes its immediate but mostly about 5 to  6 revolutions later and at times much later. As per BOTS the issue is with the RD spring which seems to have lost its tension a little. Any idea if we can overhaul the RD.

Other than this the bike is running fine. Finished the Kanakapura 200 using the same bike. 

Thanks everybody for their suggestions.

Regards

Anil

[Opendro]

Good to hear that. A little bit of learning helps maintain bikes without spending on replacements.

[Shankar Shastry]

Overhaul of RD would generally mean replacement of jockey wheel, cleaning, lubing and setting it up for indexing properly. I'm guessing you're talking about the spring under the B screw? If yes, you can just chop it down by two rings carefully and you're good to go.

[Ashok Kumar S]

Can this be done by self or do some bike shops do it? I too feel the tension in my commute MTB RD is way less. 

Thanks and regards,

Ashok

Sent from my iPhone

[Shankar Shastry]

If you have the right tools, you can do it yourself. For the rd tuning, you just need allen keys and a screwdriver. And new jockey wheels if you're replacing.