So I test rode a Rail 7, and heard a knocking I didn't like

[BadPiggy]

Test rode a 2021 Rail 7 yesterday locally. Rode it to a nearby location where there was some very steep punchy climbs on grass. While riding up this in the lowest gear under turbo, at the point of maximum difficulty, there was a loud clunking/banging sound from what sounded like the motor. Tried the same climb again in eco, and trail without problems. Try again in turbo with the same result. Felt as though it had jumped a gear in the motor/transmission. I don't know the cause, but I took the bike back straight away.

This has me very concerned about buying a Trek Rail, and for sure not this particular bike. For reference, I've test ridden two Specialized Turbo Levo's (two sizes since I'm dead between medium and large) up the same location without issue, though they do have their own potential issues. I'm basically narrowed down to these two bikes. Maybe its just a bad motor? But that doesn't comfort me much. But before I totally eliminate it, I wanted to ask all of you about your experiences.

Thanks for all input in advance.

 

[Fuellerr]

I had a Rail 9.8 and sold it for this reason, after a while the motor noise just really bothered me and seemed to get louder. The other issue was the paint chipped if anything touched it and I really wasn't happy with that after paying $8500.00. I reached out to TREK and they basically told me tough luck so I will never consider another TREK bike again.

 

[GrandesRoues]

I tested one, here in the Alps ont the speepest climbs i have on hand, and i'm an XL rider.
No problem with the XT transmission, no skipped gear. Looks like your test bike was not setup properly, may be a bent derailleur hanger ?

As for the noise of the motor, this is another topic. Compared to a Brose Levo, it is louder when lightly pedaling, but the same under heavy load.

 

[BadPiggy]

I tested one, here in the Alps ont the speepest climbs i have on hand, and i'm an XL rider.
No problem with the XT transmission, no skipped gear. Looks like your test bike was not setup properly, may be a bent derailleur hanger ?

As for the noise of the motor, this is another topic. Compared to a Brose Levo, it is louder when lightly pedaling, but the same under heavy load.

Thanks for your response. Good to hear you didn't have an issue in the Alps. The grade I was riding up was very short and probable about 30-35% grade, but no more than 8-10 feet/2-2.5 meters elevation gain. Enough to see what it could do.

I can't totally be certain it was not a problem with the cassette, I really don't think it's likely for several reasons. I firmly felt the impact of whatever it was in my feet, and the cranks did not behave as you get when you skip a tooth on the cassette (I've done that several times on a regular bike). On a regular bike, a slipped chain on a cassette under high load result in considerable crank movement (crashed in the middle of a highway once due to this), where this moved only a little bit. The noise also seemed to be from directly below me, but that could be false as is often the case with creaking. But the biggest reason that I don't think a slipping chain was the problem is the fact that I did the same spot multiple times in both Eco and Trail mode that did not produce the problem. The same amount of total torque is required at the cassette (just much more of it from my legs) in order to make the climb. However there was no issue in Eco and Trail mode. So the identifiable variable here is the peak power output of the motor, therefore this leads me to believe there is an issue with this motor.

Still could be some other issue that I haven't though of, or just the luck of the draw.

Thanks again.

 

[GrandesRoues]

There is a freewheel in the crankset. May be when there is a skipped gear the ring moves (moved by the motor) but the cranks travel less as the freewhell spins then catchup. A more experienced ebike rider could enlighten us on this.

It could also be the teeth on the freewhell who weren't engaged fully ?

I have ridden also a Moustache and a Cannondale with the same Bosh motor, without issues.
I prefered the Shimano transmission, as it handles change under torque better.

As for the torque for climbing, it was the same only if you climbed at the same speed (witch i doubt, as turbo gives you 85N.m more !).

Theses bikes are a lot of money. If you want to be sure, i would ask for another test (for free !), and try to make the noise happen again.
A good test would be an all out start in turbo mode on a steep incline (max torque from your legs + motor) * biggest ratio. May be put a go pro (or a phone with a quadlock) to film the transmission to see what is going on ?

 

[BadPiggy]

First, thank you for you reply.

The torques I was writing about, was in relation to the stress on the cassette. I was trying to explain that the stress on the cassette should be similar, as I was make the same climb at a similar speed, with the variable being how much power was coming from the motor instead of my legs to apply that stress on the cassette. I was using this reasoning as an indicator that what I experienced was not the chain "slipping" on the cassette, or jumping teeth as the stress at the cassette should have been similar in all instances. Therefore I concluded it must in fact be in the motor, as it appeared to be from the sound, and from feeling it in my feet. Sorry I wasn't more clear.

You are correct, the torque from the motor would have variable. I tried to control for speed as much as possible, but was not watching the Purion. However I can say that breaking over the top where maximum power was required and the problem occurred was very similar. At that point it was not a matter of was it 15mph/24kph vs 11mph/18kph. It's more like 2.5mph/4kph versus 3mph/5kph on the various attempts. In other words, barely clearing it.

After thinking about all this some more, I would liken it to tightening a screw with an battery powered drill to the point the screw is sunk all the way in and the motor begins to slip. The clicking/banging whatever you want to call it, was not nearly as fast as that, but it did have the quality about it as though it was slipping gears.


Thanks again.

 

[Doug Stampfer]

Try another one & see if it makes that noise. There is no perfect ebike no matter what brand.