Pedal strikes

[cjm_wales]

I had a few clangers this morning - directly into the rhs crank arm. Bad enough to score the alloy!

Is this something I should be worried about?

 

[R120]

No, its something you need to get used to - a lot of us have fitted shorter cranks, I run 160mm for instance, but the key is really adjusting your technique and getting used to reading the terrain.

Its a common thing on EMTB's

 

[TheBikePilot]

Nah. Happens a fair bit when your starting out on an eBike as @R120 says.

Mostly down to technique but reducing the crank by 5mm to 160/165mm can elimate/alleviate them. But then that’s another £50-£100 you have to spend ?

 

[Lad]

160mm cranks and pair of nylon protectors. They will not stop pedal strikes but at least scratches and gouges on the bottom bit of arms are less obvious.

 

[Donnie797]

160mm cranks and pair of nylon protectors. They will not stop pedal strikes but at least scratches and gouges on the bottom bit of arms are less obvious.

View attachment 12938

buuuut... reducing the crank length by 5mm and adding 3mm (?) of nylon is not that of a big gain. I would definitely opt for shorter cranks, they totally make sense on an e-bike. And don't care about scratches too much. Sooner or later you will have adopted your riding-over-obstacles style and terrain reading skills so you don't strike your pedals anymore. We've all been there

 

[cjm_wales]

I'm more worried about damage to the motor than I am about the battlescars!

All that force goes straight into the crank tube & motor mechanism?

 

[Peaky Rider]

I'm more worried about damage to the motor than I am about the battlescars!

All that force goes straight into the crank tube & motor mechanism?

You're right to be concerned, pedal strike on my Jam2 last Thursday resulted in powerloss and a hard pedal home.
The impact had severed one of the Di2 cables in the engine compartment.

 

[2unfit2ride]

You're right to be concerned, pedal strike on my Jam2 last Thursday resulted in powerloss and a hard pedal home.
The impact had severed one of the Di2 cables in the engine compartment.

Yet another case of Di being useless on a mountain bike

 

[Peaky Rider]

Yet another case of Di being useless on a mountain bike

No, you misunderstand. It was not Di2 gearing, my bike has standard gearing.
The same Di2 cables as used in electronic gear shifting are used to connect the motor to the controls and display screen and it was one of these cables, hidden under the motor cover, that had failed.
And the failure was my fault, although the design/protection could possibly have been better.

 

[OlaGB]

I got some deep narrow trails where i live, and even after developing ninja skills in pedal timing, i must say shorter crank arms is the best upgrade ive done to a bike for a long time!
I feel like i can pedal everywhere now!

Went from 170 to 155, so yeah big difference..
does`nt feel the slightest odd to me, neither do i notice cadence or torque/power difference.

 

[dirt huffer]

I use to run carbon cranks without protector boots. Had quite a lot of rock strikes. Never compromised the arms until about 4 years later one of the arms split like wood while pedaling.

Anyways, if you're due for a pedal upgrade check out OneUp's aluminum pedal. They're pretty thin

 

[steve_sordy]

I'm new to emtb and have been bemused by the issue about pedal strikes and the relief that people feel when they fit shorter crank arms.

My Focus Jam2 has a BB height of 350mm, with 165 crank arms. ie the centre line of the pedal is 185mm off the ground at its lowest point (no compression). With full compression of 150mm, there would be 35mm clearance.
My Whyte T130 has a BB height of 315mm, with 175 crank arms. ie the centre line of the pedal is 140mm off the ground at its lowest point (no compression). With full compression of 130mm, there would be 10mm clearance.

Yes, I know, I am unlikely to have full compression with one pedal at its lowest point, but I show the figures for comparison.

With pedals level, and at full compression, the lowest point is 200mm for the Focus emtb and 185mm for the Whyte.

I use DMR Vaults on both bikes and I have never had a pedal strike on my emtb, which does not surprise me given the extra clearance. I had the occasional pedal strike on the Whyte, but not enough to move me to shorten my cranks. I'm still on the Bike Radar forum and it does not appear to be an issue there.

I asked a mate of mine about this topic. He has been riding emtbs for much longer than me and he ventured a theory that people with emtbs get used to pedalling all the time, even around bends and consequently have more pedal strikes. It's a theory that would explain the incidents, but is it likely? Or are we both missing something? Are riders riding into more technical and rocky terrain simply because they are on an emtb?

 

[2unfit2ride]

I asked a mate of mine about this topic. He has been riding emtbs for much longer than me and he ventured a theory that people with emtbs get used to pedalling all the time, even around bends and consequently have more pedal strikes. It's a theory that would explain the incidents, but is it likely? Or are we both missing something? Are riders riding into more technical and rocky terrain simply because they are on an emtb?

Yup, most people on EMTB's haven't a clue about mountain biking & avoiding obstacles in general, obvs most people on this forum do but its not the norm.

 

[cjm_wales]

I used to tackle some gnarly stuff on my boardman hardtail, and it would get through without touching - although I wasn't going through as quickly

My two 'go to' local trails are quite varied, but what catches me out are a few 'rooty' and 'rocky' crests that don't have a clear run up, meaning I have to pedal to gain the energy, and if I don't time the burst, or I'm in the wrong gear, it's almost impossible to roll through.

I am getting the hang of keeping the outside pedal low & trying to put weight on it too. I think shorter cranks will the the next thing I try if I can't sort it with skill.

 

[Doomanic]

Paging @Gary to the thread...

 

[Gary]

can't be bothered Dom

there is a pretty useful search function here if anyone wants to read my thoughts on the subject.

yeah.
thought not

 

[Pdoz]

Or are we both missing something? Are riders riding into more technical and rocky terrain simply because they are on an emtb?

Most ebikes have a wider q factor than conventional bikes so we're catching objects to the side of the traditional riding line ?

It's got nothing to do with old men with old eyes riding at young person speeds......at least not until someone markets photochromic autofocus mtb riding goggles .....

 

[Dax]

I'm fairly sure you get more pedal strikes on an ebike because you are cranking through terrain that you would be freewheeling through on a regular bike.

I don't really care about pedal strikes, it's foot strikes that bother me

 

[Doomanic]

can't be bothered Dom

OK, I’ll do it then.

You could always learn to read the trail...

Jus’ sayin’...

 

[TheBikePilot]

..But I guess these guys haven’t learnt yet that’s a skill they need to master. However, pain and hardship is a good tutor.

I had many a pedalstrike when I first started eebing, now I don't have any.

 

[OlaGB]

But you have to stop pedaling alot more often than if you have shorter cranks!

In a technical uphill, that would be to make it or not make it. Ofcourse, you dont need shorter crank arms, but they sure are nice to have.
Would be surprised if the emtb brands dont go shorter on stock arms very soon.

 

[Donnie797]

Would be surprised if the emtb brands dont go shorter on stock arms very soon.

It's already happening. I've tested a Ghost eBike last year and instantly asked the shop guy if these are shorter crank arms, cause they felt different to me. Yes he said, 155mm crank arm length as stock.

 

[steve_sordy]

Another two reasons that might be emtb related then?
From @Dax "cranking through terrain that you would be freewheeling through on a regular bike."
From @Pdoz "most ebikes have a wider q factor than a conventional bike, so we're catching objects to the side of the traditional riding line?"

Sorry @Dax , not convinced. My eyes would tell me to pause or to stop pedalling, take a different route, manual, whatever. I can't believe that I would just crank on through.
Now you're talking @Pdoz , I will go measure my two bikes and compare. They must be damn close though as I still haven't had a pedal strike on my emtb.

I'm coming around to the views expressed by @Doomanic and @Jonny2

 

[steve_sordy]

Ref "q" factor.

I thought I knew what q factor was , but before I went to measure it, I thought I should confirm what it is exactly. I found this video which is a very interesting "talking head" address from "Bike Fit Advisor". He certainly seems to know what he is talking about and he opened my eyes to how much more there is to q factor. Despite the vid threatening almost 19 mins, it actually finishes after just over 14 mins.


What I picked up from the vid is the impact of tyre width on q factor. As most emtbs have wider tyres, it looks like it might be tyre width, not the motor width, that is contributing to wider q factors on emtbs. My words, not those of the "Bike Fit Advisor".

PS: I now know the difference between "q factor" and "stance". Every day is a learning day!

 

[Gary]

TL : DW ?

Blatantly stolen from elsewhere:

• Yamaha PW-X Q Factor Length: 168 mm
• Shimano E8000 Q Factor Length: 175 mm
• Brose Drive T, TF, S Q Factor Length: 179 mm
• Bosch Performance Line Q Factor Length: 180 mm

Just for Ref purposes:
Shimano SAINT cranks on an 83mm BB shell have a Q factor of 188mm/
XT are174mm

Does it matter?
No. Not really
In reality while mountainbiking, stance width makes very little difference to pedal strikes as you "should" very quickly get used to a wider stance or lower BB the same as you *should* be getting used to every other dimension change on a new or different bike. And you *should* be paying attention to where your feet are in the first place regardless of what your pedal stance width is.
Same applys with bar width.

Hand eye co-ordination and visual spacial planning are the only real issues .


I regualrly switch between Q factors ranging from 143mm to 188mm between my various bikes
and switch between bars ranging from 680mm to 800mm
Do i end up spending all my time striking my pedals on obsticles or knuckles on trees on the wider components? No.

Just do what Dom said.

 

[Dax]

So based on Garys numbers, my kenevo has about 5mm wider stance than my regular bike. I dont think that's enough to make me hit stuff at the side of the trail that I didn't hit before.

 

[Gary]

Take pride in everything you hit your pedals off.

...afterall each collision is entirely down to your own judgement, commitment and hard work.

 

[steve_sordy]

Nice Diagram @Gary

 

[Peaky Rider]

Steve

I'm sure you already know this, apologies if you have already mentioned it, but the Q factor on your Focus and all Shimano Steps bikes is the same as non e-bikes.

And regarding pedal strikes, surely they are directly related to the type of terrain you ride.

I have never had a pedal strike on a fire road, a trail centre track nor little woodland single tracks, but I can take you on routes where even the best can get caught out.

 

[steve_sordy]

Steve

I'm sure you already know this, apologies if you have already mentioned it, but the Q factor on your Focus and all Shimano Steps bikes is the same as non e-bikes.

And regarding pedal strikes, surely they are directly related to the type of terrain you ride.

I have never had a pedal strike on a fire road, a trail centre track nor little woodland single tracks, but I can take you on routes where even the best can get caught out.

No I have never measured the Q factor on any bike, but thanks for giving me the answer as it will save me the bother.

The rest of your post implies that you think I have a problem with pedal strikes, I don't. I was reacting to those that were saying that pedal strikes on an emtb were an issue. It hadn't been a problem for me and I was wondering why it was a problem for others. As always I try to learn and asked a few questions.

Currently, most of my miles are on relatively benign trails in the woods. But I have been all over; Peaks (Beast, Jacobs Ladder), Antur Stiniog, the French Alps to name only a few, and yes I've had the odd pedal strike. But as I said in my post - not enough to want to shorten my crank length.