- This topic has 85 replies, 47 voices, and was last updated 5 years ago by geex.
-
It better ride so much better than anything else ..
-
sharkattackFull Member
That black one actually looks better as the ugliness isn’t so highly concentrated on the frame.
Plus it looks like a prop from a sci-fi film rather than a commercially available mountain bike.
kerleyFree MemberThe only view that matters on a bike is the view over the handlebars.
Don’t agree at all, I prefer to ride a bike I like the look of and care about details that make it look nicer (shape of hubs, cranks etc,.). It is part of cycling to me.
mcj78Free MemberI think it actually looks quite “purposeful”
It’s certainly no Alchemist…
andytheadequateFree MemberThe front half just looks like an ebike, so a bit ugly but fairly normal. The back is a bit strange though.
Heard some good things about the actual performance. I like that some companies are trying different things, if all bikes looked the same it’d be a bit boring.
chiefgrooveguruFull MemberI’ve heard mixed things about how it rides and the overwhelming thing when descending is that it has an absolute ton of pedal kickback (due to the anti-squat increasing massively deeper into the travel when you’re in higher gears).
It’s an odd design because it does exactly the opposite of what loads of well regarded short-link bikes do, which is to have high anti-squat around sag for good pedalling but lower anti-squat deeper in the travel to reduce kickback.
chiefgrooveguruFull Member“Who pedals deep into the travel when descending?”
No-one I’d hope! But that doesn’t stop the suspension pulling on the top half of the chain and causing your pedals to push back against your feet.
geexFree MemberNo-one I’d hope! But that doesn’t stop the suspension pulling on the top half of the chain and causing your pedals to push back against your feet.
while the rear wheel is turning forwards and the cassette has a freewheel?
kenneththecurtainFree Memberwhile the rear wheel is turning forwards and the cassette has a freewheel?
Yes. Suspension can cycle up and down generating chain growth a lot quicker than the spinning wheel can accommodate. The freewheel is irrelevant, it allows slip in the opposite direction (if it couldn’t exert tension on the top part of the chain, you wouldn’t be able to pedal around).
The effect was very noticeable on some older DH frames with high single pivots.
DezBFree Membersimon_g
Super V Carbon anyone?
Yes please. Back then, Cannondale showing how to make a bike that looks different, but also cool. Pretty much the opposite to Marin.
geexFree MemberYes. Suspension can cycle up and down generating chain growth a lot quicker than the spinning wheel can accommodate. The freewheel is irrelevant, it allows slip in the opposite direction (if it couldn’t exert tension on the top part of the chain, you wouldn’t be able to pedal around).
Except any hit that causes the suspension to reach deep into the travel is going to be hard enough to make that top portion of chain lose tension.
The freewheel helps it stay loose on the rebound.
there is no noticable pedal kickback freewheeling with an adult stood on the pedals.
suspension action will be slightly compromised but the pedals will stay exactly where the rider wants them unless a he rides DH sat down no feet on the pedalsThe effect was very noticeable on some older DH frames with high single pivots.
No it wasn’t.
for one thing old DH bikes had very little mech tension and when it got rough the chain would slap like ****. ie. not under tension at all while freewheeling.
high single pivots were awful to pedal and shit under rear brake drag but your pedals would not kickback while weighted and freewheeling at all.
I can only assume you mistook the poor suspension performance while braking and the horrible feeling through the pedals that it gave for what occurred while freewheeling.
#Brakemuchbro?chiefgrooveguruFull Member“Except any hit that causes the suspension to reach deep into the travel is going to be hard enough to make that top portion of chain lose tension.”
This seems the wrong way around to me? If the line between effective pivot point and rear axle crosses the chain, then using any travel will pull on the chain. The more travel you use, the more the chain will be pulled, unless the effective pivot point drops lower.
tobyFull MemberSalesmen: “We’re having trouble selling these expensive ebikes because they look too different from normal bikes.”
Everyone else: “OK, we’ll build more compact motors, integrate the battery with the frame and make the ebikes more like normal bikes.”
Marin: “Hold my beer and watch this…”
geexFree Memberrear brake dragging/locked the chain will do as you imagine.
Freewheeling it won’t.kenneththecurtainFree MemberExcept any hit that causes the suspension to reach deep into the travel is going to be hard enough to make that top portion of chain lose tension.
You’re getting this the wrong way round. When the pivot is above the chain line, the hub moves backwards relative to the top of the chainring as the suspension compresses. This has the effect of lengthening the chain between the back wheel and the chainring. This engages the freewheel, so the tension acts to rotate the crank backwards. This is kickback. It is more pronounced at lower wheel speed, as at higher wheel speed the spinning back wheel can partly compensate for the chain growth.
The effect was very noticeable on some older DH frames with high single pivots.
No it wasn’t.
It just was though. My old Orange used to kick back a lot. It was more noticeable in lower speed hits, like hard exits from chutes. I used to do lots of chainless runs at my local track (dunkeld), the suspension was much smoother through the rougher sections than when it had a chain, as there was no kickback.
#Brakemuchbro?
Actually I do, ‘cos I’m not a particularly talented bike rider. Thankfully I’m a much better engineer than I am bike rider.
ferralsFree MemberThankfully I’m a much better engineer than I am bike rider.
Is that not a given on STW 🙂 …. assuming we count IT as a form of engineering
geexFree MemberYou’re getting this the wrong way round.
Nope.
You’re forgetting what actually happens when a rear bike wheel is hit hard.
you’re also forgeting what actually happens at the cassette while the wheel is turning forwards.
and you don’t seem to have even considered what the combination of the two means will happen when a 12st rider is stood on the pedals holding the cranks level underfoot.in all those slow speed chutes you mention. You had to be braking. how else can a chute be ridden at slow speed?
as I said. rear suspension performance will be compromised. But rearward crank rotation (pedal kickback) will not happen while the pedals are weighted.
kenneththecurtainFree MemberNope.
I can only assume you’re trolling now, so I’m out.
Chain growth is a well understood phenomenon. If you’ve got access to some modelling software, you could mock up something to demonstrate the concept in 5 or 10 minutes. If you don’t, some bits of string, a bit of wood, and a few nails will suffice.
Brake squat is a different issue.
geexFree MemberI understand chain growth perfectly well. the thing is with a rider freewheeling your concept doesn’t work the way you think it does in real life. no amount of nails and string is going to to replicate the real life situation.
re-read my last post. I’ve edited it slightly for it to hopefully be easier for an “engineer” understand.
tomhowardFull MemberBut rearward crank rotation (pedal kickback) will not happen while the pedals are weighted.
Will the rider not feel the kickback then, because it no longer exists if they are stood on the pedals?
geexFree MemberThe rider will feel a number of forces. (including AS forces)
The cranks won’t rotate backwards though.
Which is what “pedal kickback” means.
clue: it’s measured in degreestomhowardFull MemberThe cranks won’t rotate backwards though.
Which is what “pedal kickback” means.They will, but the rider stops them from doing so. The feeling the rider gets is from pedal kickback.
geexFree Memberand as I explained. it is minimised by the rear wheel rotating and the cassette freewheeling.
The faster the rotation the more it will be minimised.geexFree MemberThat Deviate video shows a pinion system with a tight (singlespeed) chain. We are discussing a derailleur geared system with a far longer, looser flappier chain which when freewheeling minimises the effect you’re trying to show.
tomhowardFull Memberit is minimised by the rear wheel rotating and the cassette freewheeling.
That has nothing to do with it? The distance between the crank and hub axles is increasing, as the slack in the chain is underneath the chainring, taking up that slack feeds the chain anticlockwise round the ring, combined with the hub getting further away is what moves the pedals backwards, which is then stopped by the riders feet.
The Deviate video shows a pinion system with a tight (singlespeed) chain.
It has a sprung tensioner behind the crank
ndthorntonFree MemberWhat about a mechanism to completely disengage the free hub in both directions on demand (i.e when your on a super steep descent requiring no peddling) and so improve the suspension performance. A switch on the handle bars maybe – or an accelerometer controlled servo that recognizes when your pointing steeply down and hitting bumps. It could be an electromagnet that temporarily pulls in the pawls in the hub – or a more simple mechanical device in the BB…
Blue sky thinking while doing boring stuff at work
geexFree MemberYou’re wrong.
the riders feet holds the crank position.
the wheel rotating forwards allows the cassette to take up the rotation (that would have caused an unweighted crank to “pedal kick” backwards). the freewheel allows it to lose chain tension again on extension. hence the chain slap you see from the top part of the chain.
The bigger the hit the more the top portion of chain bounces.
if what you are saying were true this would not happentomhowardFull MemberWhat about a mechanism to completely disengage the free hub in both directions on demand (i.e when your on a super steep descent requiring no peddling) and so improve the suspension performance. A switch on the handle bars maybe – or an accelerometer controlled servo that recognizes when your pointing steeply down and hitting bumps. It could be an electromagnet that temporarily pulls in the pawls in the hub – or a more simple mechanical device in the BB…
IIRC Canyon (maybe YT) already worked on it (well, the disengaging freehub anyway)
chiefgrooveguruFull Member“and as I explained. it is minimised by the rear wheel rotating and the cassette freewheeling.
The faster the rotation the more it will be minimised.”Exactly. But it’s still there. And when it’s happening it restricts the suspension movement, it feeds back into the rider’s feet and it increases the chance of losing the chain.
geexFree MemberWe agree chief. (I think you knew that already)
One thing I omitted here is. We don’t ever freewheel over rough undulating ground with our crank arms in a fixed rotational position anyway. We pivot the pedals/cranks and the bike around that axis constantly.
if pedal kickback (sus compression, chain induced rearward crank rotation) was a real issue when freewheeling you would struggle hit a big dirtjump take off on any full sus without rider stability being thrown off.
DezBFree MemberWho’d’ve thought a thread about an ugly bike could’ve turned out so….. boring?! 😆
greyspokeFree MemberFor pedal kickback (as opposed to some other effect you might notice) to happen when freewheeling the wheel would have to move backwards (relative to bb) at the same speed as your cog’s teeth would be moving forwards to pedal you at the speed you are rolling.
Imagine dropping 2m to flat. Your terminal velocity is given by the square root of (2 x g x d) where g is the acceleration due to gravity, d is the height you have fallen. So say root 40, lets round up to 7 m/s. Your rear wheel may be momentarily kicked upwards at that speed until your suspension starts to slow it down.
Your wheel will only move away from the bb by a proportion of that, say 20% max? so 1.4 m/s. That chain speed would move you forwards at 1.4 x wheel diameter/cog diameter. Lets say wheel diameter is 29, cog diameter is 2 (both in inches, an 11t cog which would be the worst case, all approximate). So that ratio is 15 ish, giving us a bike speed below which you will feel kickback of 21 m/s or 50 odd km/h.
I appear to have demonstrated that you will feel increasing kickback as speeds drop below 50 km/h when in the 11t cog on a 29er and hucking from 2m. Tbh I would be bloody amazed if I haven’t gone wrong there somewhere, anyone want to review my assumptions and calculations? In particular, some evidence of actual wheel vertical speeds when hitting bumps would be good.
ndthorntonFree MemberYou need to work out how far the pedal moves as well as how fast.
If it moves at 21 m/s for 1mm than I wouldn’t loose any sleep.mikewsmithFree MemberWho’d’ve thought a thread about an ugly bike could’ve turned out so….. boring?!
I know, think I’ll see if I can get a test ride and see what I think, could probably get a couple of laps in before this lot stop arguing.
greyspokeFree MemberYou need to work out how far the pedal moves as well as how fast.
…Well no I don’t really. Do you?
The topic ‘It better ride so much better than anything else ..’ is closed to new replies.