ebike front cogs

[dazzer10]

I have an mtb that had a conversion kit installed it has 7 speed cassette and a triple front , the bike originally had a triple cog in the front but since it had the conversion it could only use two cogs in the front, so i was thinking would it be better to use the two bigger front cogs ?

 

[sjpt]

I have an mtb that had a conversion kit installed it has 7 speed cassette and a triple front , the bike originally had a triple cog in the front but since it had the conversion it could only use two cogs in the front, so i was thinking would it be better to use the two bigger front cogs ?

That depends on your cycling style and needs. If you are over 70 and it is hilly you probably want the small two. If you are young and fit and like to bomb around at 20mph (legally without assist) you almost certainly want the top two (though beware of stress on your knees ... two single points of failure).

 

[Nealh]

Why can't the front triple be used ?
I have had triples on more then 3 ebikes that worked fine.

 

[dazzer10]

Why can't the front triple be used ?
I have had triples on more then 3 ebikes that worked fine.

Well it never worked that great before the conversion but the front is Shimano Acera Low Clamp, 34.9mm, Bottom Pull, 3x9-Speed, maybe its just old and worn , It could be because i changed the gear shifter from 9 speed to 7 speed ? or my front crank is 9 speed and the cassette is 7 speed free hub , chain is 9 speed ,

 

[Nealh]

Likelihood are the cams/stops are worn if after cable adjustment is correct and still not changing up or down.
My Boardman started to suffer poor changing so I ditched the Shimano XT in to the scrap bin and fitted a new £12 Sunrace triple dual pull and the difference was/is far superior, the reach is better and is the smoothness of operation.

 

[dazzer10]

Likelihood are the cams/stops are worn if after cable adjustment is correct and still not changing up or down.
My Boardman started to suffer poor changing so I ditched the Shimano XT in to the scrap bin and fitted a new £12 Sunrace triple dual pull and the difference was/is far superior, the reach is better and is the smoothness of operation.

does it matter what speed front derailleur i get, the cassette is 7 speed , gear shifters 7 speed , I am thinking of changing the chain from 9 to 8 speed ,

 

[Nealh]

The front shouldn't matter, a triple should still manage whether 7,8 or 9 sp chain is used. The travel is much the same, the main thing to check is the triple can accommodate your largest chain ring.

The triple I bought to replace the Deore XT, set up and adjustment was very easy.
Even with a drilled out mag disc attached to the granny ring the triple easily had the reach with a max 48t front ring.
Sunrace Triple Dual Pull Front Derailleur (sjscycles.co.uk)

 

[dazzer10]

The front shouldn't matter, a triple should still manage whether 7,8 or 9 sp chain is used. The travel is much the same, the main thing to check is the triple can accommodate your largest chain ring.

The triple I bought to replace the Deore XT, set up and adjustment was very easy.
Even with a drililed out mag disc attached to the granny ring the triple easily had the reach with a max 48t front ring.
Sunrace Triple Dual Pull Front Derailleur (sjscycles.co.uk)

i picked up a new front derailleur and i can use all three cogs but the problem i am having is, from the largest cog it will go to back to the middle but it wont go back to the small cog , i can hear it trying to but wont move i am not sure if its the settings or not ..

 

[Nealh]

How about a few nice clear pics of the fitment from all angles.

My Sunrace that replaced the Shimano Deore XT is smooth and direct in changing up & down, the fitting and adjustment was so easy.
Is the derailleur positioned correctly the clearance between the derailleur frames arc and the large chain rings teeth should be close 2 - 4 mm max
Is the wire tension correct, it should be taut but not so taut it won't flex a tiny amount.
Have you adjusted the L&H screws correctly ?

The signs of it wanting to change though is a set up issue, so it isn't far from working and just needs some or one fine set detail sorting out.

Before doing the below make sure all the above re correct.
If it is not changing from mid to small (low chain ring) try undoing the L adjuster to see if it changes, if it doesn't change down after screw adjustment then likely the wire tension is too taut, one could try slackening off the trigger adjuster or lightly undoing the derailleur tightening bolt until the change occurs.