My Custom Upgrades to Stromer ST2 and ST5 (Silent brakes,Tubeless, dropper suspension post, shimano brake caliper, 11-51 cassette)

owelt

New Member
I have owned a stromer ST5 for 8000km since 2018 and wanted to share some modifications, i wish i knew were possible when i got this bike 2 years ago.

My first Upgrade was a PNW coast suspension dropper post.
I was not satisfied how ugly the bodyfloat looked and performed, and how springy it was. also i wanted a dropper for descending comfort, mountainbiking and adjustability on the go, yet not go without suspension. It is possible to wire a wired dropper post through the stem, all internal to the seatpost. it is a tight fit but doable. It is more efficient, and just as comfortable for big bumps. It also looks slick and is an upgrade to the cockpit. I cut off a few mm of the grip to accommodate for the dropper post lever.

For the longest time i have wondered how it would be to have a 11-51 tooth cassette on a stromer st2 or st5. I planned to upgrade to a 10-51 tooth shimano deore 6100 cassette and a sram axs wireless shifter. (yes cassete and shifter are compatible and supposedly work great) Since i was able to fit a 11-46t cassette on the bike which is compatible out of the box, i delayed this plan for now. Instead i got the chance to upgrade a relatives Stromer ST2 to a 1x11 with deore 11-51 11s cassette, and it turned out amazingly. I wanted the ST1X 1x crankset but they shipped the wrong one.

Somebody mentioned how dt swiss rims are tubeless ready out of the box. it sure is so i went ahead and installed maxxis ardent tires on the bike. Downside is the whisperquiet pirelli tire noise is replaced with a louder but cool knobby tire noise. i also put some vittoria airliners in there in case of a flat so i can ride home. If i could choose my tires again i would go for vittoria e-barzo or e-martello, as they look nicer and fit better to the stromer look. the 2.4in ardents feel incredibly good, also in corners. Totally love it.

I tried cleaning the pistons of the trp caliper, and i accidentally popped out a piston. i was unable to get them to seal up again. i noticed the brake hose looks similar to the shimano 520/deore/xtr non banjo connector. and it is plug and play. I ended up installing shimano deore 6100 quad piston calipers. the shimano brake pads D03S are also compatible with the original trp brakes. They are organic pads, and completely eliminate all brake noise. it was fine before but as soon as it would get wet it would squeel horribly. with the shimano pads, both front trp original and rear shimano "Tek-mano" brake are completely silent in all conditions. Stromer pads wear very slowly thanks to regen braking so i reccomend these pads to anyone. they are also much easier to get.
 

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bluecat

Well-Known Member
For the longest time i have wondered how it would be to have a 11-51 tooth cassette on a stromer st2 or st5.

For your Puch G with reduction gearing, AT tires are the good choice. Going slow is this cars destiny.

But the ST5 is the fastest street legal E-Bike, so I wonder why you (plan to) do this bike slowing down with super slow cassette and tires?
 

owelt

New Member
For your Puch G with reduction gearing, AT tires are the good choice. Going slow is this cars destiny.

But the ST5 is the fastest street legal E-Bike, so I wonder why you (plan to) do this bike slowing down with super slow cassette and tires?
it is still speed capped, so slower tires doesent reduce its speed, just adds grip. cassette is to get up steeper offroad climbs with lower assist levels
 

bluecat

Well-Known Member
slower tires doesent reduce its speed, just adds grip. cassette is to get up steeper offroad climbs with lower assist levels
I have to confess, I don't understand.

With the ST5-Pirelli, the speed in the corner is higher then with any other tire. Especially MT tires with big amount of negative profile are allowing only reduced speed. With 52 : 51 transmission, you are at 10km/h while pedaling 75 rpm. This is far below of the ideale for efficiency of the ST5 motor.

If you want to follow the Puch G with an electric bicycle, why not with a Flyer Goroc4 6.50 HS CH?
 

owelt

New Member
I have to confess, I don't understand.

With the ST5-Pirelli, the speed in the corner is higher then with any other tire. Especially MT tires with big amount of negative profile are allowing only reduced speed. With 52 : 51 transmission, you are at 10km/h while pedaling 75 rpm. This is far below of the ideale for efficiency of the ST5 motor.

If you want to follow the Puch G with an electric bicycle, why not with a Flyer Goroc4 6.50 HS CH?
Need i say more.... cant really go above 10 KMPH up something like that :) efficient or not, its a gear that is nice to have and in support mode 1 or 2 overheating is not an issue.
The goroc was not out when i bought this bike in 2018. i would have almost sold mine to buy the flyer. but the stromer is the better allrounder for what i need it for, despite the obvious drawbacks. The Flyer comes with NX eagle drivetrain, a sr suntour fork, crappy wheelset and it looks fugly compared to the stromer, miss me with that. ( Flyer still looks reasonably good though). I really really prefer the direct drive properties of a hub motor, and an indepentent drivetrain. middrives feel awful in comparison. you dont feel the motor with the stromer, you feel like superman while pedaling. I bought an xc mtb hardtail because i loved the feeling a real bike gives you. stromer and real mtb feel very similar while mountainbiking. a middrive is almost no longer a real bike when it comes to feel.
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bluecat

Well-Known Member
Need i say more.... cant really go above 10 KMPH up something like that :) efficient or not, its a gear that is nice to have and in support mode 1 or 2 overheating is not an issue.
Thanks for clarification.

As my Stromer was new, I did similar thing to reach looking points. As mine has three chainrings, the gearing was not the problem. But the risk of overheating and killing the motor was.

But I had to install a FOX suspension fork! With the rigid alu fork, the downhill was horrible. The same in winter, when the snow has frozen lines from the riders the day before. Since the FOX is in duty, steering has become much more comfortable on road and beside it.


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