Chain skip on fastroad ex pro
- Thread starter patersont
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TheEqualiser
Active Member
The standard chain should be a KMC e.10 Sport, which I think should have 122 links out of the box. If you are changing like for like in terms of cassette then that should do you but you can always count the links when you take the old one off.
How many miles have you done on the old chain and who has told you that you need to change the cassette and the chain? If the only symptom you have is skipping on the smallest cog then I would probably check first if your limit screw is set far enough out. If your chain was stretched too far I would expect other changing issues too - sluggish changes/not always shifting up (or down) consistently. A chain checker is easy enough to get hold of and is a fairly useful thing to have for an e-bike, especially if you do a lot of miles.
Personally, I tend to avoid the smallest cog on my Fastroad as the motor can put a lot of stress on both the chain and cog.
How many miles have you done on the old chain and who has told you that you need to change the cassette and the chain? If the only symptom you have is skipping on the smallest cog then I would probably check first if your limit screw is set far enough out. If your chain was stretched too far I would expect other changing issues too - sluggish changes/not always shifting up (or down) consistently. A chain checker is easy enough to get hold of and is a fairly useful thing to have for an e-bike, especially if you do a lot of miles.
Personally, I tend to avoid the smallest cog on my Fastroad as the motor can put a lot of stress on both the chain and cog.
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steve mercier
Well-Known Member
yes just lay the old chain next to the new one and remove links to the same length. You probably ( like me ) will wear out the smallest cogs because you are going as fast as the motor can assist you. It is possible to buy and replace only the worn cogs but I always replace the whole cassette. Ebikes go through chains and cogs fast. You might want to replace the front ring also at the same time. P.S. I seem to have accidentally turned on this thick font ... (-:
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patersont
New Member
Thanks for the responses, i have only done 350 miles but do ride it 95% of the time on the smallest cog, new to ebikes and didn’t realise the effect this would have, I will adjust my riding style to protect the bike a little more, I did take a tumble in December and had not used it until last week when I experienced the chain slippag. I rang the Giant shop and they advised worn chain and cassette and to replace. I am booked in tomorrow for them to sort. I am new to servicing bikes so not sure of the limit screw you are referring too. Any help on this would be appreciated and I will tweak and test today versus the 50mile round trip to the dealer.
p.s the chain and cog look in good condition
p.s the chain and cog look in good condition
TheEqualiser
Active Member
Your chain should definitely not be wearing out within 350 miles, even without any maintenance, but you could conceivably have damaged the smallest cog if you are never out of it. It appears that one of your problems is that the Fastroad EX has no front derailleur and you have only a 42 tooth chain ring, whereas the Fastroad E+ that I ride has a front derailleur and a choice of 34 or 50 tooth front chain ring. Your 42 (front) to 11 (rear) gear ratio gives you a "cruising" speed of around 28-31 mph at a pedaling cadence of 90-100 but I guess you may have a lower cadence than that for a lot of the time. One option you would have is to ask the shop to put you a larger fron chain ring on but that is for you to discuss with them based on your normal cadence etc.
You should treat your rear derailleur like your gearbox in your car. You wouldn't try to set off from lights in your car in fifth gear - you would start off in a lower gear and build up to the higher ones. It's the same with your bike, especially an e-bike, you need to get used to changing down to lower gears before you stop and then setting off in the lower gear before changing back up to the higher gears. It's the same with hills - try and get used to pedaling at a steady rate and changing gear to suit, so if you are going downhill you will be in higher gears, if you are going uphill you will be in lower ones and if you are on the flat you will be somewhere in between. It's all about finding a comfortable cadence that you can pedal at, and happily maintain, for long periods. I aim for 90 to 100 but you may be comfortable with less. Have a look at https://www.bikecalc.com/speed_at_cadence for an idea of the likely speeds you can achieve in various gears.
As far as adjusting limit screws goes, there are several useful videos on YouTube. The Park Tools ones (e.g.
) can be very helpful if you are a newbie. We all have to start somewhere but the more you undertsand about how things work on your bike, the more confident you will be about maintaining, diagnosing and repairing it yourself, which may save you a bit of both time and cash. Plus, it gives you more chance of knowing whether there is something seriously wrong or whether it is just a simple quick fix.
You should treat your rear derailleur like your gearbox in your car. You wouldn't try to set off from lights in your car in fifth gear - you would start off in a lower gear and build up to the higher ones. It's the same with your bike, especially an e-bike, you need to get used to changing down to lower gears before you stop and then setting off in the lower gear before changing back up to the higher gears. It's the same with hills - try and get used to pedaling at a steady rate and changing gear to suit, so if you are going downhill you will be in higher gears, if you are going uphill you will be in lower ones and if you are on the flat you will be somewhere in between. It's all about finding a comfortable cadence that you can pedal at, and happily maintain, for long periods. I aim for 90 to 100 but you may be comfortable with less. Have a look at https://www.bikecalc.com/speed_at_cadence for an idea of the likely speeds you can achieve in various gears.
As far as adjusting limit screws goes, there are several useful videos on YouTube. The Park Tools ones (e.g.
steve mercier
Well-Known Member
Buy a chain checker tool...they are cheap.
bob armani
Well-Known Member
"I tend to avoid the smallest cog on" Oh yeah, that does in fact cause issues with your drivetrain. I think I'll have to change cog selection over the long term after seeing premature wear on the small cogs from this point forward. In your opinion, if you have wear causing chain slippage under load, would you replace the cog or the entire cassette? Currently facing this issue right now. Thanks for the heads up!
TheEqualiser
Active Member
There is nothing really wrong with just replacing the worn cog rather than the entire cassette but make sure you check your chain at the same time. A worn cog can damage a chain and a worn chain can damage ALL of the cogs.
bob armani
Well-Known Member
The chain alone was just replaced and that is when the problem with the 2 smallest cogs became more apparent. The other rear cogs are working without issue.
I am having my LBS use the special tool to check the other cogs on the entire cassette. Probably make my decision then, based on their findings. Thanks much!
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PedalUma
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Great advice from all. Just a new chain will make it worse. I like the KMC e-10. On some bikes I will put on a 9-Sp shifter and cassette and chain for 10, 11, and 12-speed bikes. These 9-sp chains are about 1/3rd beefier and last much longer on mid-drives. I never need or almost never need the lowest gears. Also keeping all clean is best. The KMC-X8 with the x-bridge side plates are very nice for nine-speeds. The number of cog teeth in contact with the chain also makes a big difference with skipping and can be upped with the turn of a screw. Here I put an 11 speed X-1 with an Eagle X0-1 chain on an older bike. It had skipping until I made the adjustment.
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bob armani
Well-Known Member
Exactly. I recently installed "KMC e10 EPT 10 Speed Anti-Rust Chain E-Bike Mountain Road Hybrid 10spd 136L Bike" on mine. Until I get it all setup properly, I will not know if there will be an improvement in performance overall. 9 spd chains 1/3rd beefier sounds like the way to go with any mid-drive system. I keep mine extra clean between rides and that was my mistake. Too much cleaning without enough lube in between. Lesson learned making sure now I do not make that mistake again moving forward.
steve mercier
Well-Known Member
Others may have already stated this but you can look at the teeth of each ring. If they are rounded down to a point instead of crisply square edged then it is time. If you replace the chain and the other stuff is already worn you will get chain suck, which means the new chain is binding and if you continue to ride this way, you will soon need another new chain as well as the other components. So if you wait too long to replace your chain then you may as well keep riding the ensemble until you are so annoyed with the performance that you are ready to change all 3 parts , cassette ,chain and front ring. If you have an 11 speed try using a Sram XX1 chain. It outlasts every other chain I have tried by a wide margin.
bob armani
Well-Known Member
Yes, I plan on going through the cogs and examine them to see if I can pick up on any irregularities. I plan on riding just on the good cogs until I get the parts. My LBS has looked at the entire drivetrain and indicated that the chainrings were in good shape. They did not immediately notice the other issues due to not testing the rotation under load which triggers the skipping problem. I have a 10spd setup, so I'm not so sure a 9 or 11spd rated chain would work. Then again, this is my 1st new chain swap on this E-bike. I would consider the Sram XX1 if it was compatible. Looking for the best parts for the drivetrain if at all possible.
rich c
Well-Known Member
If you had a fall, and the skipping is on the outside gear, I bet your derailleur hanger is bent and that is the problem. Or the cable has stretched. Most bike shops will do a derailleur tune up after 100 miles because of the stretch. Watch a youtube video, you can adjust the cable right at the shifter. I have almost 5,500 miles on the original cassette on my Haibike and only the second chain. I replaced the chain at 2,500 miles. No way both should be worn out at 350 miles.
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steve mercier
Well-Known Member
Bob you cannot use an XX1 on a 10 spd as it is only available in 11 speed.
bob armani
Well-Known Member
Thanks Steve. I was also researching yesterday and a well known biker (Sheldon Brown) was explaining how not to interchange 8,9,10.11 and 12 speed chains. I am hoping that the KMC e10 EPT will give me a good run moving forward.
bob armani
Well-Known Member
From my understanding, the hanger was checked out and no problems found. I will mention that when I get back to the LBS. I started seeing skipping problems at approx 2,000 miles. I have also played with the shifter barrel adjustment as well, which actually did tweak it for a better finer tune.
creativepart
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PedalUma
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Among all of the factors mentioned, all good, count the number of teeth engaged with the chain on the smallest cog. If it is four that are fully engaged than that is not good enough. Adjust to make it five.
This is why I adore internal gear hubs on mid-drives. I will drop the rear cog to 16-T and keep the ring at 42. Sheldon says 24.2MPH at 80RPM on a Nexus/Alfine 8. The HL1 Wide half-link chain kicks butt and lasts as long as a belt. Bigger chainrings than 42 overstress motor components. Do not be tempted. I have gone up to 58-T to find this out the hard way.
This is why I adore internal gear hubs on mid-drives. I will drop the rear cog to 16-T and keep the ring at 42. Sheldon says 24.2MPH at 80RPM on a Nexus/Alfine 8. The HL1 Wide half-link chain kicks butt and lasts as long as a belt. Bigger chainrings than 42 overstress motor components. Do not be tempted. I have gone up to 58-T to find this out the hard way.
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