Rail (625Wh) you may want to watch this #TREKRAIL
- Thread starter Richiefromboston
- Start date
Ark
Active member
Hows this guy straight up buying Bosch motors?
I can confirm that this happens. This is my neibours original motor where the bracket bolts sheared off on the drive side only. He had to replace the entire motor without warranty. Trek Corporate claimed this was a result of peddle strikes.
I intend on replacing the motor housing and the brackets on the drive side but so far the parts are not available to me (CDN). Btw, $800 for a replacement motor.
I intend on replacing the motor housing and the brackets on the drive side but so far the parts are not available to me (CDN). Btw, $800 for a replacement motor.
2WheelsNot4
E*POWAH Master
Can you not just extract the broken screws ?. Then replace.
Easier said than done. I have several easy-outs but not one small enough. It seems as though the threads are damaged also. Likely from movement until the bolts finally sheared off. The mounting holes in the bracket appear to be reamed out also.
It doesn’t seem like removing the broken bolts are/is possible. The casing is white metal or magnesium I think and the holes are very small.
bazxa
Member
I agree, that's poor design. It's a mountain bike & the occasional pedal strike is inevitable.
JP-NZ
E*POWAH Elite World Champion
Considering the number of CX Gen 4 out there I would say this is a pretty minor occurrence
I agree. But I wonder if they were designed to be smaller. The bolts would snap/break before the casing would crack. Same results though …replace the motor.
These bracket bolts do not hold the two hafts/sides of the motor casing together …just the motor mount brackets. They are weak when compared to the motor/frame mount bolts.
Anyways, if I could get these parts I would have a spare motor. Which I will likely need someday.
Formulasuper
Member
Sounds like the bolts had started coming loose before they broke.
Yes they can come loose so keep an eye on them. Bosch replaced my motor under warranty when it happened on my Cannondale
Yes bolts were modified to stop this issue early 2022
Wilbur
Active member
Modified how? Any pics or evidence?
Sorry no photographic evidence, but I was recently at a bike show and was speaking to the head Bosch engineer. I explained the loose bolt issue I had with my old Rail. He had a motor with him and showed my that they now fitted new bigger gauge bolts.
If I recall, you can tell if you have the new bolts as they are now standard hex bolts were the old ones had the anti tamper pins in the centre.
Formulasuper
Member
Sounds like the bolts had started coming loose before they broke.
Formulasuper
Member
That’s why it’s important to do a preflight before taking off.
riddlemethis
Member
Helicoil viable?
Yep, continued to happen to me in first 1.5 years of riding my Rail. Four new drive units in total with bike down about 14-16 weeks in total during this time waiting. Last time in fall, was off bike (back on my regular bike only for 8 weeks while waiting). Problem when the chincy motor mounting bracket comes loose, motor is not stable in frame and starts to tug and tear wires if not snapping the bolt heads off, thus sending off error codes until bike totally craps out on ya like did me last at bottom of 2500ft DH I had to grind back out with no power. Trek always eventually took care of me, but I will never own a Bosch system again cause of this despite the Rail being a fun bike to ride and Trek always good to me in the end. My Rail was 625w/h version as well. Not sure if anything changed for the 750 Smart system version though?
Numerous times for me in 1.5 years of riding my Rail. Four drive units in total warrantied by Bosch/Trek. Shoddy design altogether unless rode like a tenderfoot and infrequently like my buddy does on his Rail 5 with his. I call BS by Trek saying due to pedal strikes. Just fess up and say chincy mounting plate for such large heavy motor on a bike that was meant to be ridden on most all terrain. Pure garbage
Contined to happen to me after that with replacement in 6/22 and 10/22. After last replacement, Trek suggested I have them drop the motor every 3 months to check for loose bolts. My answer, a second ebike with none of these problems to spread the load
Wilbur
Active member
Why didn’t you do it yourself once you realised what the cause was??? Takes about 10min
Rather ride than drop motors and tighten bolts all the time. Trek was insistent they do it with Trek store just around the corner from me
And I don’t believe a rider should have to do that all the time, especially at cost of bike and what bike was intended for. If I was a mechanic and worked in a shop and got large discount on bike and had time to tinker with it, maybe not care as much. But I am not and just want to ride my God Damn bike when not working or doing family stuff without having to sweat BS like this all the time. Poor design, simple as that
I had two bolts cracked. I'm confident to say that it's not about the bolts getting loose. It's more that the M5 is too thin for the use. The new version of the motor has M6 bolts.
Getting the bolt off the motor can be very challenging. I had to put helicoil to the other thread. The alumininum/magnesium cover is very soft around the bolt.
Getting the bolt off the motor can be very challenging. I had to put helicoil to the other thread. The alumininum/magnesium cover is very soft around the bolt.
Yep, I have this torque bit and always had Trek still check to confirm if bolts snapped or not. Two of the times the were able to remove the snapped off bolt heads and replace. Other times they couldn’t or was to late with torn electronics wiring, thus requiring a full new drive unit
Wilbur
Active member
I checked mine before going on a week long riding trip last month.
Will likely check them again in a month or so.
Be good to find some stronger M5 screws…
Will likely check them again in a month or so.
Be good to find some stronger M5 screws…
With Bosch increasing the size of the bracket bolts from m5 to m6 on the newer (2022)gen4 cx motor shows that a larger bolt is necessary. Claiming that peddle strikes is causing bracket bolts to come loose and eventually snap is an easy way to blame the rider/owner for a poorly engineered design. Ensuring that bracket bolts are properly tightened puts the blame on dealers or operator abuse from owners/riders. Typical scapegoating. I’m sure they have a loss/profit formula for this issue that keeps Bosch in the profit margin and moves the cost and blame to owners.
Somewhere in the process, before the bike is ridden, there was likely a failure in engineering or manufacturing assembly or pre-sale maintenance. But it seems easier to have an owner suffer the consequences rather than Bosch. We’ll done Bosch …we’ll done.
Somewhere in the process, before the bike is ridden, there was likely a failure in engineering or manufacturing assembly or pre-sale maintenance. But it seems easier to have an owner suffer the consequences rather than Bosch. We’ll done Bosch …we’ll done.
Wilbur
Active member
So I've done a little research on replacement M5 screws for Gen 1-3 Bosch motors. The originals are black M5 x 16mm flanged security head (T25 5-pt pentalobe). The 11mm flange is not serrated. The head is ~3mm tall. They don't appear to be thread-forming as the tip isn't blunt-tapered, (even so, Bosch recommend not removing the screw completely when tensioning/resetting in order to preserve the threaded aluminium material). The coating appears to be black oxide or maybe zinc.
Ideally I'd like to replace them with a M5 x 16mm flanged and serrated class 12.9 cap screw.
Class 12.9 non-serrated:
McMaster-Carr
Or Class 8-10 serrated :
McMaster-Carr
Ideally I'd like to replace them with a M5 x 16mm flanged and serrated class 12.9 cap screw.
- Flange is important as it spreads the load on the aluminium brackets.
- Serration would be good to improve screw grip in the presence of vibration.
- Class 12.9 is the highest tensile strength alloy steel available (170,000 psi) and a cap screw can have a 4mm allen socket, instead of the annoying pentalobe head.
- Flanged cap screws are a little taller (5mm vs 3mm) than the original heads so I need to check frame clearance
Class 12.9 non-serrated:
McMaster-Carr
Or Class 8-10 serrated :
McMaster-Carr
Last edited:
I wonder if those heads might be too tall for clearance’s in the motor compartment?
