Tire pressure vs. experience?

[Elwood]

I got a Nik 100v about a month ago, coming from a V8f, and have been playing around with speed and tire pressure. It seems the more you ride a bit faster, the more comfortable it is, I guess looser you ride. With about a 100 miles on the Nikola and just trying to push it till I get shaky and nervous, I can get in the 20 to 21 mph range at 30 or so psi. If I go to 35, which seems what most people talk about riding at, I'm wobbley as heck. So the question is, is it more of a time and experience thing to gain speed and comfortability, or is it more tire pressure low enough to not feel twitchy. I'm maybe 175 all geared up, and old, so just wondering keep it at 35 ish and get used to it, or get used to it at 30 and start bumping it up when 25 gets to seem comfortable. I'm maybe 425 total miles in, in 5 to 8 mile rides, and the goal is to ride easy at 25mph on average bumpy streets. I tried to ride the V8 again after a month of the nik, and could barely it, lol.

[alcatraz]

Pressure is all personal. Depends on a ton of things. Most pressure gauges can't be compared because of inaccuracy. 35psi on one gauge could be 25psi on the other.

Just ride what you prefer.

I like it when the tire really soaks up bumps so I ride as low pressure as I possibly can, but I always have to be careful and top up so I don't leave without enough and puncture the inner tube by bottoming out the rim (snakebite). OR deform the rim.

In cycling, there is a trick to find out a good pressure. It's when the tire compresses by a certain amount like 15% (with your weight on it). For EUCs I'd say that number is way higher but it does make for a great comparison. Ignore the actual pressure. Focus on how much the tire compresses.

I only ride smooth roads and I love comfort so I'm likely close to near 50-60% compression. However, that's not to say I recommend others to do so. It works for the tire sizes I use.

Some tires can't be run with low pressure because the sidewalls are too thick. The wheel becomes too squirrely. Some tires work very well with low pressures like the CST C1488.

Edited October 30, 2021 by alcatraz

[mrelwood]

The Nikola mostly came with the mentioned C-1488 tire. While it’s a good one in it’s own right, it is indeed typical for the tire to become a bit wild when increasing the pressure. And being a soft walled tire, the good pressure range is narrower than on most other tires.

30 psi on the C-1488 sounds maybe slightly low on the Nikola tire size for a 175 lbs rider, so I wouldn’t go much lower. But it won’t cause any issues for relaxed riding on level ground either.

On the MSX the firmware has this strange small tilt-back at exactly 20mph. The Nikola is from the same era, so I wouldn’t be surprised if it has the same. The tilt-back fights back on any acceleration attempt, so getting squirrelly at your experience level because of it wouldn’t surprise me the slightest.

 One thing will surely help though: Experience. Just ride more, and you’ll became more harmonious with your wheel, and you’ll learn to relax your feet at all riding speeds.

[Elwood]

I changed my stance a bit today, and it made all the difference. I was doing Mickey's offset to avoid wobbles from his vid's. I moved the back foot up more forward and it locked the whole thing in tight. Hit 26mph without any squirreling effect. Actually made everything more steady. I'll bump the tire up to 34/35 and see how that goes. What a difference a inch or two makes.

[Tawpie]

There is no substitute for experience... and your recent discovery about stance is a good example of that. An offset stance works for some, for others not so much. Same with tire pressure. Experience will not only give you time to discover 'your' individual recipe for success, it will train the autonomic systems to compensate for an increasingly large number of variables.

My advice is not to be toooooo eager. Ride your current setup and find the top speed at which you are perfectly comfortable, then push past it a little bit, and back off when things get out of kilter. Then give yourself time to get comfortable at that new speed. Get comfortable turning at that speed, definitely learn to brake from that speed (braking wobbles are very real and are every bit as dangerous as speed wobbles). Then push it a bit more. Before you know it, you'll be lusting for a Sherman.

Just keep in mind that when you are pushing, there is some chance the wheel will punish you. Your Nik+ can go fast enough to result in serious injury, so be certain to gear up and gain your experience where a car won't run over you after your gear saves you from the fall.

Have fun in the meantime, and know that the speed will come.

Edited October 31, 2021 by Tawpie

[rcgldr]

7 hours ago, Elwood said:

I changed my stance a bit today, and it made all the difference. I was doing Mickey's offset to avoid wobbles from his vid's. I moved the back foot up more forward and it locked the whole thing in tight.

I question the offset feet idea for preventing wobbles. One issue is that a wobble tilts the wheel left and right, as well as yawing (steering) the wheel left and right. The tilting left and right means the pedals are oscillating up and down in opposite directions, and combined with offset feet, tilts the wheel forwards and backwards at the same cycle rate as the wobble, with the wheel probably cycling between accelerating and braking at the same cycle rate. The other point is how much effect is offset feet going to have on a 26 kg wheel?

As for tire pressure, in this video Duf typically has to run lower pressures to prevent wobbles because of his stance.

https://www.youtube.com/watch?v=2q0MSbSr03E&t=65s

I read somewhere you can check for tire pressure using chalk. With the EUC turned off, put a chalk stripe across the tire (from tread edge to tread edge), turn it on and ride it straight for a short distance. Then turn off the EUC and look at the chalk stripe on the tire to see how much was erased from the center of the tire while riding it straight. About 1/2 to 3/4 of the total tread width erased from the middle was the range I read about. 

 

 

Edited October 31, 2021 by rcgldr

[mrelwood]

2 hours ago, rcgldr said:

I question the offset feet idea for preventing wobbles. One issue is that a wobble tilts the wheel left and right, as well as yawing (steering) the wheel left and right. The tilting left and right means the pedals are oscillating up and down in opposite directions, and combined with offset feet, tilts the wheel forwards and backwards at the same cycle rate as the wobble, with the wheel probably cycling between accelerating and braking at the same cycle rate.

While your theory in itself seems sound, I don’t think (and I haven’t experienced) the amount and end effect to be noticeable.

 An offset foot placement sets one foot forward by 1-2 inches. If you press the pedal at 0,5-1 inches in front and back of the axle, you won’t get much in terms of acceleration.

OTOH, by simply applying pressure at the heel on one leg and at the ball of foot on the other, you already get a difference of about 7”. So the pressure balance between the feet should be much more crucial, and able to null the effects of the offset placement.

I don’t ride offset myself though, since I’ve ridden so much on bumpy grounds. Taking a bumpy curve at 20mph is enough to create a wobble if riding with an offset placement.

2 hours ago, rcgldr said:

The other point is how much effect is offset feet going to have on a 26 kg wheel?

The point of offset foot placement is to increase the distance between the front and rear spots where one can apply pressure on the pedals. Increasing the aforementioned 7” to 8-9” does noticeably decrease the effort required to accelerate and brake.

The weight of the wheel doesn’t account to much when a rider 3-5 times it’s weight applies pressure to the front of the pedals. All the weight does is increase the inertia of the wheel rotating front to back around it’s axle.