Gears slipping

C

Code54

Member
I recently got my first E-MTB (Giant Stance E+2) and have a question on setting the gears property.
I noticed that sometimes when I am on a steep slope and putting a lot of pressure tot he pedals my gears changes and I am not shifting. Sometimes this really throws a wrench into things and I figure it is also not real great for the bike. It appear everything is all lined up but what is the best way to set this up correctly and check everything? There were literally 2 bikes left in the US in my size so I had to make a 600 mile round trip for this one so running it back to the dealer is not really an option unfortunately (The dealer also seems to have figured this out and did VERY little in the way of setting up the bike correctly.)
Anyway, just want to make sure I do this right so any suggestions and idea would be great. Thanks!
 
Code54 said:
I recently got my first E-MTB (Giant Stance E+2) and have a question on setting the gears property.
I noticed that sometimes when I am on a steep slope and putting a lot of pressure tot he pedals my gears changes and I am not shifting. Sometimes this really throws a wrench into things and I figure it is also not real great for the bike. It appear everything is all lined up but what is the best way to set this up correctly and check everything? There were literally 2 bikes left in the US in my size so I had to make a 600 mile round trip for this one so running it back to the dealer is not really an option unfortunately (The dealer also seems to have figured this out and did VERY little in the way of setting up the bike correctly.)
Anyway, just want to make sure I do this right so any suggestions and idea would be great. nks!
Click to expand...
It is likely a simple derailleur indexing adjustment. There are good YouTube videos that can teach you how too do it yourself. It is also a quick adjustment that any local bike ship could do for you. Some shops cop an attitude about ebikes in general or about working on a bike they did not sell to you. Trek shops are generally very good about working on any bike.

Sometimes a little simple strategy works. Go into a local bike shop and buy an accessory, a light, a bag, a better set of grips or some pedals. As you are checking out, mention your derailleur needs adjustment and ask if they can help. They might be more willing to help if you show you are willing to be a good customer going forward. It is worth building a good relationship with an LBS, especially under your circumstances.
 
There's a great chance the derailleur was perfect when you left the shop, but there was a little stretch in the cable as it settles in. My LBS does a 100 mile checkup to handle just that kind of situation. Unless you want to run back to the shop all the time, learning how to adjust the derailleur will certainly help.
 
Adjust your derailleur setup:

check the connections, and adjustment screws. Make sure you don't have a bad cog set etc.

The first think I would check is where the cable attaches to the derailleur. If it is slipping, then... But most likely your "index" is off enough that it is close enough between gears that allow it to slip down to the smaller cog under pressure. This also is more of an issue when the chair is more "slanted" from front to back. It gets more slanted on the highest and lowest cogs. If you check the index alignment while in the extreme gears, it is more "non perfect" than when it is in the middle cog. Hope that helps.

You can take a rope, hang it from the rafters, and suspend your bike. Put something white on the ground as background. Get a light. It is pretty easy mechanics and fun to do.
 
Thanks!
What is the recommended way to get perfect center on the gears. I have a shop stand and about every tool I could ever need ( we have a full shop for auto and heavy eqpt), just not sure the best way to get it set perfect. I slipped on my first ride and I made some adjustments and it worked a lot better. noticed it slipped again today and thought my adjustment maybe a hair off and I am missing a trick or two. Thanks everyone!
 
Code54 said:
Thanks!
What is the recommended way to get perfect center on the gears. I have a shop stand and about every tool I could ever need ( we have a full shop for auto and heavy eqpt), just not sure the best way to get it set perfect. I slipped on my first ride and I made some adjustments and it worked a lot better. noticed it slipped again today and thought my adjustment maybe a hair off and I am missing a trick or two. Thanks everyone!
Click to expand...
Alaskan already told you, watch YouTube. Lots of bicycle mechanic techniques there. You should also look at chain stretch, and cassette gear wear. A chain slip is not automatically a derailleur problem. A shop full of auto and heavy equipment tools will still leave you short for bicycles.
 
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Was planning on watching some Youtube stuff tomorrow but as a seasoned mechanic I know there is often little things we know and can do to make a job much easier that may or may not be in a video.
As I mentioned the bike is just about brand new so chain stretch and a new cassette hopefully is not an issue yet. LOL.
 
Watch to see if the derailleur centers the chain on the (right) gear. If it's rubbing up against the gear on either side of it, it's not set properly. Then go ride it. If the derailleur isn't up shifting and down shifting perfectly, without dragging, you most likely still don't have it indexed properly. A little patience REALLY pays off here. Small changes can make a big difference. Use the adjusting nut on the end of the cable for adjustments.
 
Start near the center or what is in a straight chain line with the front. Make it perfect. Go to the top and the bottom. Check them to make sure they are close to centered, equally off a bit because they are at the extremes. The amounts off are about 5% of the chain width or less. Use your ears too. Smooth is good.

The derailleur should move in a good parallelogram. Some are not so good and get asymmetrical at the extremes. That should not happen. Go try it. Likewise you should be able to make it NOT work by being obviously maladjusted.

Also know that the shifter can be messed up also, but rare. Make sure your shifter and derailleur are compatible, of course. Lastly, derailleurs are not that expensive if you want to upgrade to a higher end "index shift spacing" compatible model.
 
Code54 said:
Thanks!
What is the recommended way to get perfect center on the gears. I have a shop stand and about every tool I could ever need ( we have a full shop for auto and heavy eqpt), just not sure the best way to get it set perfect. I slipped on my first ride and I made some adjustments and it worked a lot better. noticed it slipped again today and thought my adjustment maybe a hair off and I am missing a trick or two. Thanks everyone!
Click to expand...
When you say "I slipped on my first ride" do you mean you fell; on the derailleur side? If so, this may have have bent the derailleur hanger. A seemingly simple 'bump' can even cause this. The hanger can be bent back or replaced cheaply, but it is indicative of your symptoms.

A quick visual check is to put the cassette in the middle cog and sight down the chain line from the rear of the bike. The derailleur arm should be 'perfectly' vertical. If not, the hanger needs adhustment/replacement.
 
Code54 said:
I recently got my first E-MTB (Giant Stance E+2) and have a question on setting the gears property.
I noticed that sometimes when I am on a steep slope and putting a lot of pressure tot he pedals my gears changes and I am not shifting. Sometimes this really throws a wrench into things and I figure it is also not real great for the bike. It appear everything is all lined up but what is the best way to set this up correctly and check everything? There were literally 2 bikes left in the US in my size so I had to make a 600 mile round trip for this one so running it back to the dealer is not really an option unfortunately (The dealer also seems to have figured this out and did VERY little in the way of setting up the bike correctly.)
Anyway, just want to make sure I do this right so any suggestions and idea would be great. Thanks!
Click to expand...
I think it is almost certainly a simple derailleur adjustment, as others have said. I had the same issue with my new Radrover a couple of months ago. New cables will stretch, so you need to make a small adjustment to compensate for this. Very simple to correct.
If you have some sort of bike stand to lift the rear wheel off the ground, it will make it much easier. Simply turn the barrel adjuster by the derailleur counter-clockwise in small increments of 1/4 to 1/2 turn to tighten the cable. After each adjustment turn the pedals and shift through all the gears to check for smooth shifting. Good luck!
Note that the article talks about loosening the cable tension by turning the adjuster clockwise. Most likely, you need to tighten the cable by turning the adjuster counter-clockwise.
 
THANK YOU, everyone. Great info.
To answer a question - Nope, no falls, the first time I got on the bike the chain slipped and made a few "auto" shifts so that is why I was thinking it wasn't setup exactly right from the start. Looks and sounds like an easy fix and I appreciate all the info, tips, tricks, and links!
 
It IS nice to be able to properly adjust a derailuer but all you USUALLY need to know is to turn the little thumbknob to adjust the cable tension. Slipping can almost always be adjusted away at the handlebar. But the deraileur end can make larger adjustments, so that is 2nd. And even small pieces of debris (grass wrapped around a gear) can cause that too. All easily remedied.
 
Yep, stretching always happens when new and then just occasionally after. It doesn't happen enough for me to remember which way to turn it, but if you do and nothing improves, then you go the OTHER way. :)
 
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