Drag!!

[Mikerb]

[email protected] that kind of drag. I mean drag caused by tyres and rear suspension.

Today I was checking over my wife's bike which is a Cube Access ( hardtail). I took it out on the road at the side of my house as part of the checkover and did a couple of miles just riding up and down what is a pretty steep hill. The bike is Bosch Gen4 powered, 625w/h battery, 12 speed, hardtail. I have never bothered to update the firmware so the motor is still 75nm rather than 85nm. Its a 29er running on Schwalbe Smart Sam tyres 2.6.
I have the same motor but at 85nm in my Whyte E180 but the difference in performance is night and day, and I dont just mean in terms of outright power.
The amount of difference a lighter bike with no rear suspension and running faster rolling tyres was amazing. I know the E180 is at the other end of the spectrum in terms of efficiency v traction but even so it was interesting feeling just how the extra drag/lack of efficiency on the E180 impacted on how the motor responded to torque input in EMTB mode. Pick up was much smoother especially when regaining speed after momentum was lost. Changing gear with less back off of power was easier and smoother despite SRAM X01 gear on the Whyte which is pretty darn good for that.

It certainly encouraged me to start thinking more seriously about the tyres I use on the Whyte if nothing else ( Assegais currently).

Having said all of that I forgot I was riding a hardtail and there is a slight ramp from the road onto my driveway which I hit quite fast and the back end nearly kicked me off!! On my Whyte I dont even notice it!!

 

[Tonybro]

That's why I like my Orbea Rise...

Hardly any noticeable drag from motor.

Tyres are a big factor.

I have been wholly unimpressed with my recent purchase of Nobby Nics but that's another discussion.

 

[Mikerb]

That's why I like my Orbea Rise...

Hardly any noticeable drag from motor.

Tyres are a big factor.

I have been wholly unimpressed with my recent purchase of Nobby Nics but that's another discussion.

OK but I am not referring to the drag induced by the motor. I am referring here to something rarely discussed in terms of bike design and something that really starts to define the difference between trail bikes, enduro bikes and even downhill bikes.

The design of the rear suspension both in terms of linkage design and shock selection and tune is always a compromise between efficiency and traction. The ride on my wife's hardtail just demonstrated to me the extreme end of the scale in terms of efficiency.
If the bias is towards efficiency much less of the power from the drivetrain is lost which makes for easier pedalling or even freewheel progress. Couple that with fast running tyres and lower weight and you are the XC end of the spectrum. Compromise a little more and you are in trail/all mountain territory.
If the bias is towards traction.....meaning the design enables the rear wheel to follow the trail contours maintaining high levels of grip and traction.......... you lose efficiency. On an Enduro bike efficiency is less a priority. Couple that with soft compound high grip tyres, a stronger frame build, slacker head angle, longer wheelbase.................and you have a bike that can thrash gnarly downhills with impunity but everything else will be harder work!!

The brands have all the information about the design criterea they employed but rarely give any insight..............and then folk modify ( the euphamism being "upgrade") their bikes without that knowledge and probably just as often impact the bike performance in a negative way as positive.............obviously depending on the sort of terrain they ride.

I would like that informaion to be more available together with professional advice on alternative suspension options etc. One way to second guess that is to " upgrade" by using the same components as the brand in a higher range model of the same bike.

 

[1oldfart]

Thanks @
Mikerb
this is an excellent subject.
It is very **a la mode** to talk about 150mm and up.
I love my Ebike 29 FS 130/120.
I do not want a long wheel base but people say these
are beginners bikes.
I say a good rider with 2 good tires are important.

 

[ChillyWilly]

It's a personal thing what kind of bike you like. I did go through the hardtail 100mm -> FS 130mm -> FS 140mm -> FS E-MTB 170mm. So you could call a 130/120mm bike an intermediate bike, but the truth is that it's all about what you like. I like all of them, but I and my riding style changed and so did my bikes.

Coming back on topic. Yes, the eeb 170 with Magic Mary / Big Betty is draggy, but still a hell of a lot faster than a mtb. You can switch to a less draggy tyre at the expense of grip.