Bosch failures?

[p3eps]

I keep reading threads from Specialized owners saying how they’re on their 2nd, 3rd, 4th... motor under warranty.
It seems the forum has a much higher Specialized ownership than anything else, so it would make sense that there are more posts about them.

The Gen4 Bosch is still fairly new, but how did the previous gen motors last? Did owners need 2 or 3 of these motors during their warranty period - or are they generally a bit more robust.

I’m going to place an order for a Trek Rail today, so am wondering about Bosch reliability. I usually get a new bike around every 3 years, so wondered if this will last... without any significant expense.

 

[Rusty]

Know of a couple guys with 2-3 year old bosch motors and they haven't had an issue. One guy knows of someone who had problems and the replacement was next day. I think it was a case of pressure washing but not too sure.

 

[GrahamPaul]

I was chatting to the owner of a bike shop in Tarifa in September last year. He originally stocked a range of EMTBs with different motors. From this year, he will only be stocking EMTBs with Bosch motors. His opinion was that they had reliability AND service/spares sorted.

Given that part of his business is hiring EMTBs to holidaymakers, that speaks volumes to me.

 

[Mad Mark]

I’ve had my bike 2 years now, it was de-restricted 1 month after it was brought & touch wood I haven’t had a single problem with it.
Everybody says the Bosch is a noisy motor, but I disagree, mine never seems louder than anybody else’s
Just a very reliable e-motor ??

 

[Beekeeper]

My collegue at work has quite an old Bosch motor. He does claim it has the small chainring on front but I’m not sure which generation. It does not have walk mode so I’m assuming an early Gen 3, not sure.
Bike is a Haibike hardtail and he works it into the ground, mainly on tarmac. 24 miles every working day for 4 years. Never cleans it, always puts it away muddy. Never had to replace anything yet and he claims not to have noticed any battery degradation. He thinks I’m crazy washing my bike.
Only issues he said he had was battery attachment to the frame is a bit suspect as it’s not integrated or even semi. Lots of punctures to begin with. Changed to Kevlar tyres and no problem now.
It was this guy who introduced me to ebikes when I knew nothing about them. I was going to buy a cheap one from Halfords.
His exact words were... “whatever you buy, make sure the battery and motor is a decent brand. I have a Bosch” he said.

I guess the rest is history ?

 

[ggx]

Not aware off any big issues on friends bikes with Bosch motors. Small issues always sorted on warranty.

 

[Bearing Man]

It is my business to fix ebike motors. I eat sleep and breath motors and that's all I do! I supply parts and fix Bosch, Brose, Yamaha, Impulse, Panasonic etc. I can tell you that they all do what they do and they do it well. I would be a lot busier and a lot richer if they all failed as much as you would believe by reading forums.
It is true that some motors are definitely better than others, but that's not an argument for me to get into. Many people ask what motor I would recommend? I say just buy the bike you like/want and enjoy it. Look after your motor and it should look after you.
Of course if your motor does fail you can find me at www.performancelinebearings.com

 

[Doomanic]

I went through three motors in 2 years. The first one only lasted 300 miles, the second and third did 900+ each. I ride in all conditions and never powerwash the bike but IMO it's the stupid small chainring at fault; crud collects round it and is ground into a paste by the chain and the forced through the bearings.

mainly on tarmac

This makes a huge difference; there are 10,000KM motors out there in commuter-land.

That hasn't stopped me upgrading to a new Rail with the Gen 4 motor though.

 

[Beekeeper]

It is my business to fix ebike motors. I eat sleep and breath motors and that's all I do! I supply parts and fix Bosch, Brose, Yamaha, Impulse, Panasonic etc. I can tell you that they all do what they do and they do it well. I would be a lot busier and a lot richer if they all failed as much as you would believe by reading forums.
It is true that some motors are definitely better than others, but that's not an argument for me to get into. Many people ask what motor I would recommend? I say just buy the bike you like/want and enjoy it. Look after your motor and it should look after you.
Of course if your motor does fail you can find me at www.performancelinebearings.com

I love your shop press machine. I bet that thing has paid for itself many times over. Wonder if that has bearings too ?

 

[Bearing Man]

I went through three motors in 2 years. The first one only lasted 300 miles, the second and third did 900+ each. I ride in all conditions and never powerwash the bike but IMO it's the stupid small chainring at fault; crud collects round it and is ground into a paste by the chain and the forced through the bearings.

This makes a huge difference; there are 10,000KM motors out there in commuter-land.

That hasn't stopped me upgrading to a new Rail with the Gen 4 motor though.

I totally agree and I think one of the reason Bosch done away with the small chainring on the Gen 4 motors.
I have been doing a few tests with the MudStop and new seals too (see pdf attached) I wouldn't advise it, but I have been deliberately riding through water deeper than the motor and no ingress yet

 

[Bearing Man]

I love your shop press machine. I bet that thing has paid for itself many times over. Wonder if that has bearings too ?

I have retired that poor little press Got a big new shiny one now

 

[Beekeeper]

I have retired that poor little press Got a big new shiny one now

Oh sorry to hear that. Hope it wasn’t water ingress ?.
Hang on to it, could be worth a fortune at auction. You have made that machine world famous ?

 

[Doomanic]

MudStop

I nearly bought one of those a while ago from Belgium but never got round to it and then I saw them on your site recently. I would have bought one next time my Gen2 died, which was imminent as it had nearly 1000 miles on the clock.

 

[maker]

First Gen 2 lasted 6 months, replaced under warranty. Software needed reseting a few months later. Replacement motor making whining noise that last time developed into a grinding before siezing. So that will be 2 motors in 14 months. Apparently they don't like water which makes them unsuitable for where I live. Someone noted fitter riders have the problem as they exert more power through the pedals and the inadequate bearing and seal lets water in.
As an update in May I've had my third gen 2 in a 12 months of riding for a couple of Months and done a lot of exercise riding in the covid lockdwn. By now my previous two motors were making friction/grinding noises. The weather has been unuaually dry and I clean gently with water; motor gets more pressure thown up by tyres in the wet. So guess it'll be fourth motor this winter.

 

[SquireRides]

Bosch GEN3, you do have to maintain it well. It has a low official IP rating (like, limited to light sprays of water). But the good news is there is a maintenance routine you can follow that will help (unlike other motors). Remove and clean the seal, pack grease behind the seal... Do that every few months depending on your riding conditions, and your bearings should last longer.

If they fail, there's a fairly cheap bearing replacement kit. So you should be able to keep a Gen3 going for years...

Personally, I had one Gen3 fail at around 2000 miles. I used to ride through a ford on one of my regular routes! Second Gen3 is at about 1500 miles, and feels fine.

 

[Doomanic]

4 motors in about 2000 miles...

I hope the Gen4 is more reliable.

 

[maker]

I didn't find any maintenance advice in Bosch bumff. When this one fails, like it sounds as if it is about to, will look at greasing replacement, and will ask shop about additional protection kits.

 

[SquireRides]

I didn't find any maintenance advice in Bosch bumff. When this one fails, like it sounds as if it is about to, will look at greasing replacement, and will ask shop about additional protection kits.

It's not described in the user manuals. There is an obscure workshop note about how to properly install a seal on a Gen3 - I think because they originally shipped without this seal. But it makes for good instruction for properly sealing the motor:

1. Remove your drive side crank arm.
2. Remove the Bosch locking ring using the Bosch spider tool.
3. Slide all chaining, spacers, and guards off (noting the order!)
4. Carefully remove the black seal. I find tweezers or needle pliers work well.
5. Clean behind, pack with lots of grease, replace seal and refit everything.

If you want to replace the seal, it's this: Bosch Performance / Active / CX Main Bearing Seal
The lockring tool: Bosch Active / Performance Spider Tool

 

[Bearing Man]

Do you mean Gen 2 motor? The Gen 3 has a large chain wheel and an aluminium washer covering the bearing and mostly used on road bikes?

 

[Boris]

I tried a trek allant 7 yesterday,just to compare the torque with my Yamaha pwx motor on my Haibike sduro 8 full susp.It was significantly less powerfull than my Pw-x motor on hills and MUCH noisier.So I really dont see why this motor is so popular.Also the Pw-x bike had 29 plus 2.6 nobby nic tire and full suspension vs hardtail and Schwalbe G-one tyre
Allant+ 7 | Trek Bikes (GB)

 

[GrahamPaul]

I tried a trek allant 7 yesterday,just to compare the torque with my Yamaha pwx motor on my Haibike sduro 8 full susp.It was significantly less powerfull than my Pw-x motor on hills and MUCH noisier.So I really dont see why this motor is so popular.Also the Pw-x bike had 29 plus 2.6 nobby nic tire and full suspension vs hardtail and Schwalbe G-one tyre
Allant+ 7 | Trek Bikes (GB)

Yet my mates have both got Haibike Sduro with the pwx motor and reckon that my Bosch Gen 4 motor feels more powerful on the climbs... Subjectivity is, well, subjective I guess.

 

[Boris]

Yet my mates have both got Haibike Sduro with the pwx motor and reckon that my Bosch Gen 4 motor feels more powerful on the climbs... Subjectivity is, well, subjective I guess.

Strange.I didnt think there was diffrent tuning versions of the new Bosh motor?I didnt test it at short sprints in very high cadence,so maybe the diffrence is there.Very high cadence for me(80+).But for longer steep hills there was very clearly that the nex cx was much less relaxing to pedal

 

[Beekeeper]

Strange.I didnt think there was diffrent tuning versions of the new Bosh motor?I didnt test it at short sprints in very high cadence,so maybe the diffrence is there.Very high cadence for me(80+).But for longer steep hills there was very clearly that the nex cx was much less relaxing to pedal

New Bosch = 340% assistance in Turbo
Old Bosch = 300% assistance in Turbo

 

[Boris]

New Bosch = 340% assistance in Turbo
Old Bosch = 300% assistance in Turbo

I tested the new motor Gen 4

 

[GrahamPaul]

Strange.I didnt think there was diffrent tuning versions of the new Bosh motor?I didnt test it at short sprints in very high cadence,so maybe the diffrence is there.Very high cadence for me(80+).But for longer steep hills there was very clearly that the nex cx was much less relaxing to pedal

Now that's really strange... and it's funny how life turns out. On Friday's I do a "coffee run" with a couple of "seniors" in their 70's. Normally I take them on a "mystery" tour but today the wind is blowing a Force 7 and one of them suggested a ride which would be more sheltered.

To add a bit of challenge they both wanted to try coming back into the town via a very steep, switchback road which has been concreted because it's unstable in the wet and slides down the hill (and currently closed to traffic because part of it slid down the hill in last month's storms). Strava is crap at giving slopes on switchbacks, but the total climb is 111m over 800m, so around 14% average, but with kicks on the hairpins of around the 30-40% mark, where too much power will cause a loop out for the unwary.

I know it quite well and headed for the top (in turbo). Then had to go back down when my "team" were nowhere to be seen. The chap on the Haibike Sduro couldn't do it. He'd stopped and was getting his breath back before trying to use walk mode up the hill (that's tough with those slopes!).

We swopped bikes and he "pootled" up the hill on mine in Turbo and bottom gear. I puffed and panted my way up to the top on his.

Again, subjectively, there's two of us here who would disagree with you.

Out of interest, the other "oldie" was on a hard tail with an older model Bosch Cx, and he had no problems climbing the hill. (Admittedly, there is a major weight and fitness difference between the two gents.)

Also, as I have a cadence meter on my bike, my cadence on this bit of hill was between 90 and 105. Tony's was between 90 and 95. So I would guess that we were both hitting the same cadence on both bikes.

 

[Boris]

I agree that Bosch is stronger at 90-105 + rpm.But much weaker on lower cadence.who wants to have such high cadence for longer period of time.

 

[Bomble]

I agree that Bosch is stronger at 90-105 + rpm.But much weaker on lower cadence.who wants to have such high cadence for longer period of time.

Coming from a 2020 levo with the 90nm brose, i demoed a trek the other day with the new 75nm Bosch and i would say it definitely feels more powerful than the brose at low cadence.
If the Yamaha has more power at low cadence than the Bosch then it must be a beast of a motor. I'm surprised it gets such little press.

 

[maker]

A bit old but Torque curves - Shimano, Bosch, Brose, Yamaha - EMTB Forums

 

[GrahamPaul]

A bit old but Torque curves - Shimano, Bosch, Brose, Yamaha - EMTB Forums

I'll see if I can find the article again, but that Yamaha power curve has been shown to be "in error" on the Spec diagram. (Must have been someone's marketing department up to mischief).

[Edit: This one New Yamaha 2020 ebike motors shows an interesting take. Can't find the recent article comparing the efficiencies and claiming that the curve had been "manipulated.]

 

[Boris]

That torque curve is wrong.
here is from a recent test with Brose S mag,TQ,Bosch cx4,Smimano e8000 .....
"
The new Giant SyncDrive Pro motor is based on the Yamaha PW-X2 and is unfazed by varied cadences in the lower and middle range. No other motor offers as much support at slow cadences."

This is the new pw-x2,which have higher cadence,but slightly lower torque at low candence than pw-x

here is the link:
Giant Reign E+ 0 Pro in Review | E-MOUNTAINBIKE Magazine