Rockrider E-st 900 changes upgrades

DT36

Member
Sep 17, 2020
73
69
S. Wales
Thank you. As you said, very easy. Put some lithium grease around the axle. 38T in place. Thanks also to Bebiker for all the information about chainrings.
38T is much better suited overall to this bike. I have a seriously steep and long hill for about 200m at the start of my ride and I can still pull it in 3rd gear, as it would on the old 34T chain ring. Very good modification and thanks to @BeBiker for the heads up. :)
 

Gary Davis

Member
Feb 13, 2021
138
79
Belgium
First thing, I mounted the Dropper Post KindShock E20.

I'm not completely (completely not) satisfied.
The marketing and manual say you can adjust the angle between cable attachment and saddle position.
This is not the case for that model, and they admitted it.

I wanted to pass the cable on the back,between the tubes.
This is not possible now.

But it works.

View attachment 39774
Hi,
I'm still hesitating but I'd like to install a dropper seatpost. I checked the essential dimensions to be sure it will perfectly fit and this one seems to be perfect.
When you decided to mount yours, did you consider running the cable along the top tube or could it be bent too much? Should be a shorter and easier way to the handlebars. Have you had to change your quick release seatclamp because of the external cable routing system too close of this clamp. Thanks in advance
 

Zimmerframe

MUPPET
Subscriber
Jun 12, 2019
14,028
20,817
Brittany, France
I'm still hesitating but I'd like to install a dropper seatpost.
That looks similar/identical to the transx one I put on the e-st500. (Which I know is not the same bike :) )


I ran the cable down to the cranks and back up.

I found some bike self adhesive cable clips which I just stuck to the frame. Some from bike discount and some from e-bay as I wasn't sure what they'd be like. One set had clips the others you just put a zip tie through them, so it looks fairly tidy.

Like this :


This was whilst I was testing the cable routing to make sure it worked ok ..

500.jpg
 

BeBiker

Active member
Aug 26, 2020
700
421
Belgium
Hi,
I'm still hesitating but I'd like to install a dropper seatpost. I checked the essential dimensions to be sure it will perfectly fit and this one seems to be perfect.
When you decided to mount yours, did you consider running the cable along the top tube or could it be bent too much? Should be a shorter and easier way to the handlebars. Have you had to change your quick release seatclamp because of the external cable routing system too close of this clamp. Thanks in advance
By the way, besides the "turn-angle" expectation, mine works still very good.
Except some milligrams difference, I don't see a reason why spending 2x, 3x, 4x...

I didn't want to put the cable along the to tube, so I didn't try that.
The seatclamp is still the original one, doesn't give any conflict.
If you decide to put the cable under the motor like me, order a 2100mm rear derailleur cable.

Last week my cheap saddle spring broke, so i'll order the PNW Coast, drop+ 40mm suspension.
I hope in april they will be deliverable again.
 

Gary Davis

Member
Feb 13, 2021
138
79
Belgium
That looks similar/identical to the transx one I put on the e-st500. (Which I know is not the same bike :) )


I ran the cable down to the cranks and back up.

I found some bike self adhesive cable clips which I just stuck to the frame. Some from bike discount and some from e-bay as I wasn't sure what they'd be like. One set had clips the others you just put a zip tie through them, so it looks fairly tidy.

Like this :


This was whilst I was testing the cable routing to make sure it worked ok ..

View attachment 55755
Thank you. However, the main difference between those bikes is the motor location and that's why I would have liked to go straight to the handlebars along the top tube. You're right, both models look similar. My main worry was about the short right angle between the seatpost tube and the top tube. Should be so easier than going down under the motor. Considering all his changes, I'm pretty sure Bebiker thought about it. Thanks also for the adhesive clips. They seem very useful.
 

Zimmerframe

MUPPET
Subscriber
Jun 12, 2019
14,028
20,817
Brittany, France
Thank you. However, the main difference between those bikes is the motor location and that's why I would have liked to go straight to the handlebars along the top tube. You're right, both models look similar. My main worry was about the short right angle between the seatpost tube and the top tube. Should be so easier than going down under the motor. Considering all his changes, I'm pretty sure Bebiker thought about it. Thanks also for the adhesive clips. They seem very useful.
I almost went along the top tube, but the curve would have been too tight, or there would have been too much of a dropping loop.

I guess you'd need to put it on the bike, get the height correct and then see where the bottom ends up.

I take it you don't think you can get it through (or there's no exit holes) the frame and out with an internal one ?

You can get away with a reasonable curve, too much and it might end up kinking or will wear faster or just be tight to operate.

It's certainly easier installing an external one. :)
 

Gary Davis

Member
Feb 13, 2021
138
79
Belgium
By the way, mine works still very good.
I didn't want to put the cable along the to tube, so I didn't try that.
The seatclamp is still the original one, doesnt give any conflict.
If you decide to put the cable under the motor like me, order a 2100mm rear derailleur cable.
Your way of doing is certainly the more "invisible" one and the shimano cable is a very good idee. By the way my original seatclamp is a quick release one
 

Gary Davis

Member
Feb 13, 2021
138
79
Belgium
I almost went along the top tube, but the curve would have been too tight, or there would have been too much of a dropping loop.

I guess you'd need to put it on the bike, get the height correct and then see where the bottom ends up.

I take it you don't think you can get it through (or there's no exit holes) the frame and out with an internal one ?

You can get away with a reasonable curve, too much and it might end up kinking or will wear faster or just be tight to operate.

It's certainly easier installing an external one. :)
You're right. Following my measurements, the collar of the dropper seatpost should be at around 3 cm from the seatclamp but I might have to replace the quick release by a less "bulky" one . I will see if the curve is too tight or not. I "confess" that I even thought about drilling in the top tube !!!
 

Gary Davis

Member
Feb 13, 2021
138
79
Belgium
By the way, besides the "turn-angle" expectation, mine works still very good.
Except some milligrams difference, I don't see a reason why spending 2x, 3x, 4x...

I didn't want to put the cable along the to tube, so I didn't try that.
The seatclamp is still the original one, doesn't give any conflict.
If you decide to put the cable under the motor like me, order a 2100mm rear derailleur cable.

Last week my cheap saddle spring broke, so i'll order the PNW Coast, drop+ 40mm suspension.
I hope in april they will be deliverable again.
I just checked the price of the KS E20 and it's more expensive than the one I would buy. Did you pay less than 120 € ? Oh ! I forgot that you described yourself as a "avaricious miserly stingy parsimonious" guy ! ???
 
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Gary Davis

Member
Feb 13, 2021
138
79
Belgium
I hope to have finally 1 or 2 weeks free time to make and mostly enjoy all the changes I want. I've already changed the chainring (38T), the front brake (shimano 6120 and 203mm rotor), mudguards. Anyway I promise to put images of all modifications when done. All of you gave me so many advises.
 
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Gary Davis

Member
Feb 13, 2021
138
79
Belgium
More seriously, I 'm not sure but I think I have seen this plug and his protection as spare parts on Decathlon French website
Update : sorry. I was wrong but this is the kind of parts quite easy to find and even more reliable at professional stores.
 
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Gary Davis

Member
Feb 13, 2021
138
79
Belgium
this is what I found :
It's not exactly the same but maybe it could help
You could also send an email to Decathlon support. I did it once and they replied quite rapidly.
 
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356fan

New Member
Mar 9, 2021
1
0
Germany
Can you tell me where you purchased the 42 and 38 chain ring ?
What do you think about a 40T.

Thanks I am in Germany


Changing the chainring (again)
Original it comes with 34t, then I changed to 42t, here a pic with the new 38t.

The chain guide goes back on, and I have enough spare chain length now.
The guide is now at maximum height in the guide-travel into the plastic cover.

First driving impressions are good.
Compared to the 42t, I have to pedal faster to go top-speed at full electric power (don't need that often)
I have more choice in the shortest gears, useful to climb without elec assistance.

View attachment 39777
 

BeBiker

Active member
Aug 26, 2020
700
421
Belgium
It was just a test, so I bought a cheap one on Aliexpress.
But surprisingly, after 600km still perfect !
In my post of 1 sep in this tread, you see the direct link to the article.

40T will also work, but 38T is the limit for using the original chain-guide.
 
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DT36

Member
Sep 17, 2020
73
69
S. Wales
Can you tell me where you purchased the 42 and 38 chain ring ?
What do you think about a 40T.

Thanks I am in Germany

Agree with BeBiker on going for a 38T. This fits perfectly with the chain guide and will see you pedal to about 27mph, as opposed to 22mph. The bigger chain ring has not had any negative effect for myself on climbing hills.

I got mine on Ebay:
 

RonnieX

Member
Jul 3, 2020
90
77
Northwest
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DT36

Member
Sep 17, 2020
73
69
S. Wales
@DT36 I’m very impressed. It’s took a few rides to fine tune the damping. Which to be fair, only takes seconds to adjust. But now it makes the stock Rockrider saddle so comfortable! ?

SUNTOUR SP12 NCX MTB ROAD 31.6 x 350mm SUSPENSION SEAT POST - BRAND NEW | eBay was the cheapest I found. It comes with a ‘meduim’ spring as standard. Soft and hard springs are available for different riders weight.
Sounds really good. My kids look to be carrying a bit of weight anyway so just added that link to my basket before I go through TopCashBack :) . Thank you.
Hopefully it will arrive this week, as the weather is picking up nice as we come out of lockdown here. I'm also in the middle of prepping a small van to take our bikes, so we can start to go further afield for rides out.
Will report back how I get on with the stem. ?
 

selamatbobo

New Member
Mar 30, 2021
2
0
France
I wanted a dropping post, so had to check dimensions to see if it would fit.
The tube is 31.6, but is it deep enough ?

I ended up buying the KS E20 125mm, mid cable

View attachment 38984

View attachment 38985
Hy, did you try to pass the cable inside the seat tube? I did it for my tail light fixed under the seat (just drilled on the tube to let the cable out to the light. Don't know if the existing hole in the frame (giving acces to the motor where I plugged my light) is large enough for the sheath. Other solution (really more expensive): wireless systems...
 

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