emtb heresies!

[steve_sordy]

Hi, Newbie to emtb here!

I have been riding mtbs for over ten years and I have always found the best recipe for tyres was grippy up front, less grippy at the rear. This to ensure that when cornering, it was always the back that gave way first, and that the rolling resistance was improved Is this not the way with emtbs?

Other heresies:

Why does bike weight no longer matter on an eBike?

Why is it that the more travel the better (as in "it will always come in handy") seems to ignore bike geometry when considering eBikes? For example, 170mm travel bikes are not that great at twisty XC.

I can't help thinking "ye canna beat the laws o' physics Cap'n!"

Please don't berate me with all the eBikes you know that conform to the "usual" rules, I'm talking about the general heard here! There must be a grain of truth in the above, or I wouldn't keep seeing the evidence.

 

[Doomanic]

the rolling resistance was improved

Less of an issue when you're flying a milkfloat; the motor compensates nicely.

Why does bike weight no longer matter on an eBike?

It does, who says it doesn't?

Why is it that the more travel the better (as in "it will always come in handy") seems to ignore bike geometry when considering eBikes?

Again, it's less of an issue when you're flying a milkfloat.

For example, 170mm travel bikes are not that great at twisty XC.

No they're not, but I would say the vast majority of bikes are in the 150mm range.

 

[kane]

If you ride twisty xc don’t get a 170 mm bike ..

 

[steve_sordy]

I was deliberately being provocative.
I was feeding back the impressions I've picked up from a variety of magazines (paper and digital) and discussions with eBike riders. I don't argue with them, after all, I don't even have an eBike yet, so what do I know? But I still have a rational mind and I'm wondering to what extend a 250W (average) power assist overturns decades of wisdom about bikes.

 

[steve_sordy]

If you ride twisty xc don’t get a 170 mm bike ..

Agreed, you make my point.

 

[MattyB]

I was deliberately being provocative.
I was feeding back the impressions I've picked up from a variety of magazines (paper and digital) and discussions with eBike riders. I don't argue with them, after all, I don't even have an eBike yet, so what do I know? But I still have a rational mind and I'm wondering to what extend a 250W (average) power assist overturns decades of wisdom about bikes.

None of the long-standing “rules” of MTB are completely invalidated by e-power, but there are definitely a few that are adjusted, or can be bent. Remember 250W is quite a bit more than the average weekend warrior can sustain, and actually these bikes put out significantly more (600-700W) than that when it matters.

All ebikes are heavy compared to an analogue bike (irrelevant of discipline), so none I’ve ridden feel as nimble, but all have more grip. Equally that weight seems to improve the suspension action on all the full suss ebikes I’ve tried so far, again improving traction. What does that mean? Well with the e-assist and bags of grip they climb great, especially those with slightly longer chainstays. They also accelerate quickly out of turns, so if you lose flow at any point it’s easier to get the energy back, though manualling over obstacles on the trail is definitely harder.

It all means the negative aspects of carrying more travel than you might normally choose on an analogue bike are somewhat negated. This is why you don’t see many short travel full suss ebikes; the most popular all seem to be in the 140-150mm range. Also remember given current battery tech realistic range is 30-40 miles (dependent on AUW and altitude gain), so at this point more ebikes tend to be towards the trail/enduro end of things rather than XC. I also suspect it’s because weekend warrior gravity riders are probably a lot more open to ebikes than your average XC racing snake!

 

[Dwazzer]

None of the long-standing “rules” of MTB are completely invalidated by e-power, but there are definitely a few that are adjusted, or can be bent. Remember 250W is quite a bit more than the average weekend warrior can sustain, and actually these bikes put out a fair bit more than that when it matters.

All these bikes are heavy compared to an analogue bike (irrelevant of discipline), so none I’ve ridden feel as nimble, but all have more grip. Equally that weight seems to improve the suspension action on all the full suss ebikes I’ve tried so far, again improving grip. What does that mean? Well with the e-assist and bags of grip they climb great, especially those with slightly longer chainstays. They also accelerate quickly out of turns, so if you lose flow at any point it’s easier to get the energy back, though manualling over obstacles on the trail is definitely harder.

It all means that the negative aspects of carrying more travel than you might normally choose on an analogue bike are somewhat negated. This is why you don’t see many short travel full suss ebikes; the most popular all seem to be in the 140-150mm range. Also remember given current battery tech realistic range is 30-40 miles (dependent on AUW and altitude gain), so at this point more ebikes tend to be towards the trail/enduro end of things rather than XC. I also suspect it’s because weekend warrior gravity riders are probably a lot more open to ebikes than your average XC racing snake!

Totally agree! Especially the part about the audience that bikes appeal to (as a generalisation ?).

 

[R120]

I think we are seeing a rapid evolution of the EMTB - To date the main quest has been to make an EMTB as close as possible to a regular MTB, the interesting thing for me will be when someone makes an EMTB that aims to be the best EMTB possible.

What i mean but his is rather than disguise and minimise all the motor/battery elements, look at what can be done with them, and how you can design around them to take advantage of the weight etc, rather than just mitigate it.

With more weight over the BB do you need to go slacker? in fact you can probably size down because of the stability? Short reach but longer trail, or the opposite? Longer chain stays for traction but geometry that allows you to still pop the front easily? Geometry that reflects what they can do and how you really do and how you really ride one.

As EMTB's become more mainstream, and with the advent of a racing series, we will i think now start to see some left field developments and interesting thinking.

It wont be long before we see a decent all in one motor/gearbox (several already in development) that will have major effects on rear end handling.

Currently we seem to see two trends, one American lead which takes a heavy Moto influence, with bikes like the new Intense Tazer that are heavily marketed towards this aspect, and on the flip side the likes of the Levo and La Pierre E-Zesty that are marketed as being MTB's with that little bit extra.

Its only really in the urban/commuitng side of e-bikes that we see people working on making the best e-bike, and fully accepting what it is.

 

[Dax]

I'm wondering to what extend a 250W (average) power assist overturns decades of wisdom about bikes.

Bikes have overturned decades of wisdom about bikes. How long ago was it we were riding narrow bars, steep head angles and narrow tyres?

In answer to all your questions, ignore everything embn says, it's shite, go demo some bikes and see what works for you. If you want some more dated geometry, maybe look at last year's levo which will be on sale at the moment. Personally I haven't had any issues on the 180mm kenevo, but maybe I don't ride proper XC trails.

 

[outerlimits]

I ride a variety of trails from tight twisty xc to all mountain & enduro.
I had a choice of a Kenevo 180mm (I think) or a Levo 150mm. I test rode both and the Levo was well balanced for my riding.
If I were to ride no xc then I would of picked the Kenevo.
Each bike would do what I asked of it but the geo definitely came into the equation.

Weight and travel are less of an issue as the motor helps you on the climbs. Extra weight also equates to more traction and wider tyres are no longer a chore to turn, and again, more traction.

All things still matter, just matter differently to a more or lesser degree. Horses for corses, you’ll still have to make some compromises, motor or not.

 

[davarello]

I agree with the answers above, the basics still apply and there will always be compromises to make - motors and batteries are always going to add weight, but the uphill speed and cornering acceleration make up for it, and in my case any XL bike I'm on (115kg) is going to struggle with tight switchbacks and emergency braking. As for tyres I'm running the Levo on the standard Butchers with Cush Core inserts (20/24psi) - no problems so far, though I may consider going slightly smaller on the rear tyre for clearance in the winter next year.

 

[knut7]

To date the main quest has been to make an EMTB as close as possible to a regular MTB, the interesting thing for me will be when someone makes an EMTB that aims to be the best EMTB possible.

I believe we're already at that point. The first fs emtbs were 480mm +. That was a result of motor design and limited frame r&d. We had to move away from that, and it seemed we were working towards the regular trailbike geometry.

For 2018 we saw a few bikes with sub 440mm chainstays, the shortest being 425mm. But not all new 2018 frames were pushing the chainstay length that far, such as 2018 BMC Trailfox (445), Devinci AC and DC (~450), Scott e-Genius (460) and Mondraker e-Crusher (450).

The Specialized Kenevo is 443mm, so I was expecting shorter chainstays on the 2019 Levo. But with 455mm that didn't really happen, just 2mm shorter than the previous model. The new 2019 Intense Tracer just showed up with 450mm stays. I believe manufacturers have canceled the hunt for trailbike geo and are focusing on, as you say, making the best emtb. Frame design/geo has always been about compromises and deciding what characteristics the bike should have. An emtb is a more capable climber and it seems manufacturers are deciding to accept longer chainstays to retain some of the "extreme" climbing abilities. Sure, geometry is more than chainstays, but I think this is a good example. In my latest reviews I've claimed chainstay length between 440 and 460 is considered normal for an emtb. Perhaps 445-465 is turning out to be the new normal.

 

[Gary]

Hi, Newbie to emtb here!

I have been riding mtbs for over ten years and I have always found the best recipe for tyres was grippy up front, less grippy at the rear. This to ensure that when cornering, it was always the back that gave way first, and that the rolling resistance was improved Is this not the way with emtbs?

Depends what your aim is.
If racing DH seriously grippiest tyres available front and rear are the one
XC racing something less grippy but much faster rolling
general riding something in the middle so yes a faster rolling but ultimately less grippy rear tyre will work well.
One thing you have not touched on is almost all of us run less pressure in the front which naturally means the rear rolls faster and the front grips more.
The idea of running a larger grippier trye in the rear of an Emtb is to harness the power in allowing the bike to climb impossible grades/technical climbs. Personally I prefer having to actually search for grip and climb using good weight distribution to create more grip.
But I've also raced DH at a fairly high level on hard compound tyres

Other heresies:

Why does bike weight no longer matter on an eBike?

It matters massively, there are folk out there saying it doesn't, there are folk saying 21kg is the optimum weight. There are folk saying heavier is better. to me this is mental. a heavy bike is more stable (all other parameters being equal) but other than that everything else is a downside until you get into lower weight than 16kg (DH bikes start to suffer from being too light around this weight)

Why is it that the more travel the better (as in "it will always come in handy") seems to ignore bike geometry when considering eBikes? For example, 170mm travel bikes are not that great at twisty XC.

You're actually wrong here. Quality of travel is far more important than amount of travel than you seem to think. I have 2x 170mm travel bikes and 2x 200mm travel bikes. a 120mm bike and lots of hardtails. The 200mm bikes aren't very good at flat XC because they have DH geometry and the suspension is optimised for grip over pedalling efficience. But put them on twisty tight singletrack on a slight incline where pedalling isn't too much of a concern and they're FASTER than an XC bike.
Now take my 2x 170mm travel bikes. both have sub 65deg H/As and both have low BBs. One id 31lb carbon enduro bike and the other a 47lb Emtb. Both bikes have very good pedalling characteristics so flat trails do not hold them back over an XC bike at all. On steep enough descents that aren't about the pedalling there's nothing between them times wise.(and very little between them and my DH bikes until it gets super rough. (where the lighter Carbon bike becomes more of a handful than the heavier Emtb. The lightweight carbon bike accelerates, pops and changes direction far easier while the heavy Emtb holds momentum and line better than even the DH bikes. Because of this they need to be ridden slightly differently to one another to get the best out of them.
Both of these bikes have supportive/progressive rear suspension and a stiff fork as I like jumping and pumping rather than plowing through shit. This makes them both extremely nimble for the amount of travel they have (and the weight of the Eeb).
The one other thing I haven't disclosed yet to get to this seemingly impossible 170mm travel but good on flat twisty trails nirvana. Do you want to know what it is?
None of my bikes are overly long. That's it. LONG bikes are harder work to raise the wheels and harder work to turn in tight slow situations. The drawback (that has never bothered me) is that they are less stable.
This preconception that a long low slack bikes can't do tight trails well is actually wrong. a 64 deg H/A will thread through tight trees and manage slow tight corners absolutely fine. A low BB is awesome for cornereing as it lowers the C.O.G. and gives you increased grip in turns. But a bike that's overly long and has long reach for the riders height actually is more difficult to control in tight situations or situations where you want to lift the front wheel repeatedly.

#Physics

having said all of the above, if you have the skills and strength you can make a loooong bike go extremely fast through tight singletrack too. not too many people can pull this off though.