Spinning the front wheel

[Mark B]

The one area of concern for me with the fwd bicycle is the all too easy ability to break the front tire loose, especially when taking off on an uphill with dirty pavement below. It seems to me there should be a technique to avoid this problem. I've not found it to be a problem going uphill under power, just on takeoffs.

Has anybody else experienced this and if so, what is your technique for beating it. So far, I've tried taking off in a higher gear than usual and that is really scary if and when the tire lets loose. I'm thinking maybe a lower gear than usual and lean into the takeoff to put more weight on the front wheel, just so you can get in motion. Your thoughts?

Mark

 

[Kamatu]

I was wondering about this myself from your stories. Have you measured your ratio? I know 50/50 is "ideal", but I think a 55/45 would do the job just as well. Also, I forget if you said (and I'm having a hard time telling from the pictures), is the rear shock adjustable so you can bias the bike against going back?

Remember that accelerating (esp uphill) will throw force onto the rear wheel, lifting the front wheel some. Admittedly it won't be much power on a bike, but then a bike isn't that heavy. If you cannot adjust more forward bias, then try leaning into it. You could also try putting more rubber in contact with the road, but that would cause other issues you may not care for. Personally, I'm going to have to use wider knobby tires because of my potential driving conditions once I get past the learning curve. My three most likely destinations all require some off road time in areas with sand, clay and gravel.

 

[Mark B]

Kamatu wrote: I was wondering about this myself from your stories. Have you measured your ratio? I know 50/50 is "ideal", but I think a 55/45 would do the job just as well. Also, I forget if you said (and I'm having a hard time telling from the pictures), is the rear shock adjustable so you can bias the bike against going back?

No, I haven't measured the weight distribution yet. It's on my list of "to do" things and something I'm curious to find out how it changes as I attempt to reshape my body. The Silvio doesn't have a shock, per se. It has an elastomer shock absorber, which is nothing more than a chunk of rubber to absorb the shock. There's no adjustment to it unless you change the density of the elastomer.

Kamatu wrote: If you cannot adjust more forward bias, then try leaning into it.

I tried this and the thing you have to keep in mind is; leaning forward closes your pedaling position, which puts more power to the pedal. This creates the proverbial double edged sword. While you are moving weight forward, you are making it easier to break the front wheel loose with the increase in power. This is why I tried it in a higher gear than I would normally take off in, which I still think is the answer, just need to work on the technique.

Kamatu wrote: You could also try putting more rubber in contact with the road, but that would cause other issues you may not care for. Personally, I'm going to have to use wider knobby tires because of my potential driving conditions once I get past the learning curve. My three most likely destinations all require some off road time in areas with sand, clay and gravel.

For now, 25c is about as wide as I want to go. I may try 28c the next time around as I get stronger.

This is good stuff.

Mark

 

[Kamatu]

Higher gear or less power on the start since you modulate how much mashing your are doing, which means leaning might be the easiest fix and slipping from a stop is always easiest.

 

[JonB]

Since the weight is on the back wheel, maybe someone could design a bicycle that is rear wheel driven? yes yes, i know it is heresy and witchcraft, but i really think it would work uphill.

 

[Mark B]

I think I need to find a place like that where I can practice different starting techniques. I tend to think higher gear/lean forward to start, but that is counterintuitive to everything you have ever learned. OTOH, so is everything else with this bike! :roll: :lol: I think too low of a gear and you would really spin that tire. I don't know how on earth you would ever start out on dirt.

Speaking of dirt. There is one interruption in the pavement on the path and it so happens to be a gulley, of sorts. The road drops off down a hill, makes a bend and climbs back up out. As I understand it, the plan is to span this with a bridge and I suppose they are waiting for money to improve it. Anyway, I rode the Silvio on the dirt going down in, where it got really soft in the bottom. I was chicken to ride through the real soft stuff and walked it through that and could tell there was no way I was going to get any traction to climb back up out of there, so I walked it. No big deal. Coming back the other direction, I rode it through the soft stuff and the bike handled it OK, but I started spinning as I tried to pick up momentum for the other side. I walked it back out of there, just to the top of the hill and rode it the rest of the way back onto pavement. The bike handles the dirt OK, so I suspect with wider, treaded tires it would be just fine for dirt roads or touring where you might encounter dirt roads. But climbing in dirt? I don't know...

Mark

 

[Kamatu]

I get past some of these small difficulties, I'll be able to let you know, at least on clay. Well, actually on dirt too, come to think of it my uncle has a twisty sand road going uphill on his place.

 

[cycleguy]

JonB wrote: Since the weight is on the back wheel, maybe someone could design a bicycle that is rear wheel driven? yes yes, i know it is heresy and witchcraft, but i really think it would work uphill.

Rear wheel drive, what are you crazy, that would never work! Besides, you'd be looked at as being different, not normal, do you really want that??

Harold

 

[JonB]

cycleguy wrote:

JonB wrote: Since the weight is on the back wheel, maybe someone could design a bicycle that is rear wheel driven? yes yes, i know it is heresy and witchcraft, but i really think it would work uphill.

Rear wheel drive, what are you crazy, that would never work! Besides, you'd be looked at as being different, not normal, do you really want that??

Harold

Yeah i see your point. What about some superbooster like cars and NOX. I'm thinking an oxygene mask and direct nose injection.

 

[Mark B]

JonB wrote: What about some superbooster like cars and NOX. I'm thinking an oxygene mask and direct nose injection.

Then you'd really, really, REALLY spin the front tire!

Mark

 

[Kamatu]

Mark B wrote:

JonB wrote: What about some superbooster like cars and NOX. I'm thinking an oxygene mask and direct nose injection.

Then you'd really, really, REALLY spin the front tire!

Mark

There is a reason race cars, especially dragsters, are still rear wheel drive.

 

[JonB]

Mark B wrote:

JonB wrote: What about some superbooster like cars and NOX. I'm thinking an oxygene mask and direct nose injection.

Then you'd really, really, REALLY spin the front tire!

Mark

that doesnt matter, because your mind would be spinning too.

 

[Hotdog]

Much as I hate to pull this thread away from the enjoyable silliness, I would like to drag it back to the original subject for a bit :roll:

Front wheel spin does seem to be an issue for me and my Sofrider V2. Things have improved after I switched to more sensible tyre pressures (about 60psi in the stock 26x1.5" tyres) and got better taking a run up, leaning forward and smoothing out my pedalling action, and I think it'll get better as my technique improves further (and possibly when I get some grippier tyres) but I'd like some idea of what sort of slopes I can expect to be able to handle in the end. Anyone here riding up extreme gradients on their Cruzbike? What are the limits? You see, Sydney is a hilly place and to take the Sofrider on my favourite rides (or even up the driveway... :roll: ) I need be able to get up short sections at grades of 10-17%. Am I just dreaming here, or is that actually achievable?

 

[Mark B]

Achievable? Yes, just don't stop!!

I've had pretty good success reducing the front air pressure by 10-15 pounds. If you have wiggle room, you can increase the rear pressure to help offset the increased rolling resistance.

Does the Sofrider have a air shock in the front like the Silvio, or is it simply sprung?

Mark

 

[Hotdog]

Mark B wrote: Achievable? Yes, just don't stop!!

I've had pretty good success reducing the front air pressure by 10-15 pounds. If you have wiggle room, you can increase the rear pressure to help offset the increased rolling resistance.

Does the Sofrider have a air shock in the front like the Silvio, or is it simply sprung?

I believe the Sofrider shock is sprung, at least there's no apparent way to adjust it (which I guess is what you'd otherwise have recommended). I'm not sure I'm game for reducing my tyre pressures much further, there are some unavoidable bumps in my regular routes which are capable of bottoming out the front suspension (with a loud 'tap' noise) and I don't want to be bottoming out the tyres too in the process (pinch flats or buckled rims aren't fun). I'd want higher volume tyres before I ran lower pressures, like a Schwalbe Kojak 26x2.0" or something.

Anyway, I stuck at it with the bike as is, and with a little more practice and determination the wheel slip issue has gotten a lot better. Last weekend I went for a ride by myself to try the Cruzbike out on some of the local climbs, and on each of the 3 pinches of over 10% grade (plus the driveway) I got the front wheel slipping, ran out of momentum and had to walk until the slope reduced. That's the experience that prompted my question about what sort of angles I might ultimately be able to ride up. Since then I've been developing my technique by attempting the driveway each day and this morning I went on a group ride which followed essentially the same route that had given me so much trouble the week before. This time, by getting as far forward over the front wheel as I could, smoothing my pedal stroke as much as possible and gearing right the way down I was able to make it up the two short, winding 10-15% pinches despite lots of debris on the path, and almost cleaned the 17% s-bending on-road climb (my legs gave out before the traction this time). To top it off, when I got home I managed to ride up the insanely steep driveway for the first time too

The wheel slip issue hasn't entirely gone away, I still generally break the front wheel free for part of each stroke on the steep bits, but I'm able to keep it under control enough now to maintain my precious forward momentum. I might be able to stop it entirely with further improvements in technique, or grippier tyres, but I can already make it up the steepest short pinches around here albeit with some slippage, so I know it's not going to be a serious problem

The only remaining question about hill climbing on the Sofrider is whether the low end of the gearing is low enough for me and my local terrain. For short steep pinches I can just force my way up at low cadence, but for longer climbs I much prefer to spin my way up at 80-90rpm. I've got the gears for prolonged climbs at 6-7% but some of the hills around here include lengthy sections at around 10% which would probably leave me struggling. Of course, the simplest solution would be just to get fitter... :roll:

 

[Doug Burton]

JonB wrote:
Yeah i see your point. What about some superbooster like cars and NOX. I'm thinking an oxygene mask and direct nose injection.

Jon - Brilliant!

We'll call it NOS-e !!!

Bwahhahaaa!!!

I spun my front wheel briefly on an uphill restart on the Sofrider Proto yesterday (27 mile ride before lunch, glorious weather for a change). Mark is right in that wider tires are less likely to spin, but the whole thing is pretty manageable - this bike is running 559x25 tires a 120psi, and is geared a little short. Also, it's a V-1 design that has higher seat height - this causes the weight to transfer to the rear faster.

 

[Kamatu]

I need to try to find a better slope. I've got some small ones I ride on, through sand, clay and mud at times and I'm starting to take off from grass and dirt, but I cannot get any slip. Of course, I'm running 24" knobbies (stock Tiara wheels) and I have the rear suspension cranked about half way back to compensate for my weight, so I might not be able to get enough transfer back to the rear wheel.

BTW, what was the handling characteristic as you tighten the rear suspension? I'm thinking about loosening it up.

 

[John Tolhurst]

Crank up the rear to increase the head tube angle and get quicker handling, if that suits you better. Lower it down to reduce seat height.

 

[currystomper]

...maybe an electric motor on the back wheel would help - two wheel drive..

;-)

Currystomper

 

[Kamatu]

johntolhurst wrote: Crank up the rear to increase the head tube angle and get quicker handling, if that suits you better. Lower it down to reduce seat height.

ROFL. You really cannot imagine how much I am laughing if I correctly understood this.

At 300 lbs and some consultation with the mechanic at the LBS before I picked up the bike, the prime failure point in his opinion with me converting the Tiara was the rear shock cylinder if I didn't crank it back. I'm 20 lbs lighter now and had someone looking at it and saying I'm not coming near bottoming the shock out. So, the learning curve problem I've been having with the front end swinging might just be a shock adjustment. :lol: :lol: :lol: :lol:

I've seen it before and didn't print it out (or it got lost in the cleaning), but can we get the list of how various adjustments to the suspension affect the handling of a Cruzbike pinned on the forum somewhere?

 

[Kamatu]

Well, I have joined the ranks of the front wheel spinners. I softened up the rear shock and I think it has helped out the front end issue, but I also tried to start in some sand on a slight incline and ziiiiip, the wheel spun (wasn't planning it, it just happened), but then it grabbed and off I went.