K2 / Proflex Riders Group
General => Tech Forum => Topic started by: TARDISBlue on June 02, 2012, 05:45:56 pm
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Hi folks. I have an ancient Proflex 4000 (no idea what size) that I used to ride casually in high school. Some trails, some backwoods, mostly as my primary form of transportation. I went away to college, left the bike at home, and ballooned to like 280lbs. I'd really like to lose some weight by getting back on it, but I tried riding and the bike just bounces as I pedal now. Spring is too light I presume. It's an awful sensation, and I'd really like to keep the bike so I just need to stiffen up the back end. I'm probably never going to do anything more hardcore than gentle trails and riding across fields again. Can anyone point me in the right direction? I'd like to do this without spending too much money if at all possible. Thanks all.
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What rear shock does it have? You should be able to go to a stiffer rear spring. Can you see any numbers on the spring you have now? May have to rotate it to see all the way around.
Also, where are you located? May be someone close bu that could lend a hand.
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I don't think I've ever lost weight from riding. When I start riding in the spring, I usually gain ten pounds of water mass, which doesn't go away again until I stop riding for a week. The only way I've ever been able to lose weight is by intentionally not eating for a couple days straight so my digestive system shuts off, and then resuming eating much smaller portions. If I screw up and eat until I'm stuffed, and my digestive system stretches out again, I have to start all over.
That being said, a stiffer spring will help but you'll also need to tighten the damping too. The stiffer spring may overwhelm the damper mechanism when the spring rebounds from a bump. If your bike can fit an air shock, that's probably the best option because you can shove as much air into the shock as you need to get the proper spring rate, and they tend to be less bouncy than coil shocks.
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What rear shock does it have? You should be able to go to a stiffer rear spring. Can you see any numbers on the spring you have now? May have to rotate it to see all the way around.
Also, where are you located? May be someone close bu that could lend a hand.
I don't have the bike with me now, but I'll check the spring for a number when I go to get it from my parents house. Where would I get a stiffer spring?
I don't think I've ever lost weight from riding. When I start riding in the spring, I usually gain ten pounds of water mass, which doesn't go away again until I stop riding for a week. The only way I've ever been able to lose weight is by intentionally not eating for a couple days straight so my digestive system shuts off, and then resuming eating much smaller portions. If I screw up and eat until I'm stuffed, and my digestive system stretches out again, I have to start all over.
That being said, a stiffer spring will help but you'll also need to tighten the damping too. The stiffer spring may overwhelm the damper mechanism when the spring rebounds from a bump. If your bike can fit an air shock, that's probably the best option because you can shove as much air into the shock as you need to get the proper spring rate, and they tend to be less bouncy than coil shocks.
I'm going into my 3rd year of law school and have been largely sedentary for so long, any exercise will help. I can't stand running and I don't want to buy an elliptical. I'd rather go biking again, as I've discovered there are great bike paths out here. I've considered going with an air shock, but I'd like to keep my investment minimal. It seems like a great choice and is still an option as it stands.
Thanks all.
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Well I do lose weight when I cycle regularly, so go for it!
(as long as you observe Energy Out > Energy In!)
It's a lot less damaging on the body than running and a damn sight more interesting than using an elliptical, (although I do have mine set up in front of the TV and a big fan to keep cool!)
At 280lb , yes you really do need stiffer springs than the standard ones, a 650lb/in was the highest that K2 spec'd on the rear of the 4000 for 210-250lb riders so maybe you even need a 700.
Bear in mind that the fork spring (if a Crosslink) may also need to be upgraded.
take the shock off of the bike and then the coil off of the shock and measure the end to end of the coil plus the internal and external diameters and you have your spec, then go searching for any make spring that will meet that spec.
Whilst you have the coil off, check the compression and rebound damping of the shocks by pressing in the piston, there should be resistance in both directions and depending upon shock model, you should be able to vary this, sounds like the shocks could have leaked during their long rest and that's why the bike is so bouncy..........search on here for Noleen service or consider an air shock as Fyrestormer says.
Good luck and keep us informed!
Col.
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I think I have a 650 spring.
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Well I do lose weight when I cycle regularly, so go for it!
(as long as you observe Energy Out > Energy In!)
It's not quite that simple. The mass of the food you eat is the primary factor in determining whether you gain or lose weight. Conservation of mass applies in dieting as well as everywhere else. Even if you burn more calories than you consume, if your overall calorie AND protein intake is higher than it would be if you weren't exercising, you'll add muscle mass faster than you burn fat. That's why bodybuilders will eat 4000 calories a day, a large portion of which is meat. Muscles are good, of course, and for a sustained exercise-based weight loss program you do need to have a good supply of muscles, but if that's the approach you take, don't be surprised to see weight gain for the first month or so -- unless you starve yourself, which is generally not good for muscle tone no matter how much you exercise.
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Looks like I have a 500 and 600 spring for an NR-2 I think.
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Thanks folks. I am picking the bike up on Sunday and hope to do a full tear down after work Monday night. I'll post pictures and such. I think I have an NR4, as I remember having a remote reservoir or what ever that battery shaped thing is on the top of the shock.
At 290lbs and 6'0", I'm mostly fat at this point. That's what I need to burn off. The weight loss is mostly for waist size and look, not actual number. If I were 280lbs and pure bulk, this wouldn't be an issue, but I'd like to fit into clothes I've had to shelve for more than a year. I overeat at meals and graze between because I spend my days at a desk. I'm back to normal size portions and have mostly cut out the snacking, or if I really need to snack I'll grab an apple or a pear instead of Ritz sandwiches or some other delicious fatty food. The bike is a much more attractive option than going to a gym or running. There are some great bike paths around here that lead to the ocean, so I'd like to give them a shot. Might even switch to street tires for the time being.
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Long day. Here are some pictures. I have no idea what the spring rates are, but they're way too soft, front and rear.
(http://i353.photobucket.com/albums/r365/lsxjunkie/IMG00852-20120610-1847.jpg)
(http://i353.photobucket.com/albums/r365/lsxjunkie/IMG00856-20120610-1848.jpg)
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Great! sounds like you're really motivated! go for it!
road slicks or whatever, get out there and ride it!
Look what I've found for you...................
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160820631566&ssPageName=ADME:B:SS:GB:1123 (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160820631566&ssPageName=ADME:B:SS:GB:1123)
(http://i.ebayimg.com/00/s/MTIwMFgxNjAw/$(KGrHqJHJCgE+QgnqW0JBP061POWIw~~60_12.JPG)
might be too stiff at 750lb/in, but would then be good for on road!
Col.
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Great! sounds like you're really motivated! go for it!
road slicks or whatever, get out there and ride it!
Look what I've found for you...................
[url]http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160820631566&ssPageName=ADME:B:SS:GB:1123[/url] ([url]http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160820631566&ssPageName=ADME:B:SS:GB:1123[/url])
([url]http://i.ebayimg.com/00/s/MTIwMFgxNjAw/[/url]$(KGrHqJHJCgE+QgnqW0JBP061POWIw~~60_12.JPG)
might be too stiff at 750lb/in, but would then be good for on road!
Col.
You, sir, are a gentleman and a scholar. Thank you.
And a question for all. What does the knob at the top of the rear shock do? The one mounted directly on shaft, not the stiffness knob.
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The NR-4 shock has two adjustments. The knob on the side near the remote oil canister is the compression damping adjuster, and the knob on the end near the pivot is the rebound damping adjuster.
Put a little oil on the shock threads before you crank down on the spring, if/when you need to adjust the spring preload. The grey threads may be anodized aluminum, but even anodizing wears out eventually. Oil will help prevent that.
Don't put slicks on the wheels. Maybe newer tires with shorter knobs, but not slicks. As long as you're riding a mountain bike, you should be able to take it off the pavement from time to time without risking losing control -- especially if you weigh almost 300lbs, you don't want the tires to wash out if you hit soft dirt while dodging someone on the bike path. Anyway, the rumbling you hear and feel from the knobby tires is wasted energy, and if you're trying to burn calories, wasting energy is precisely what you need to do.
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The NR-4 shock has two adjustments. The knob on the side near the remote oil canister is the compression damping adjuster, and the knob on the end near the pivot is the rebound damping adjuster.
Put a little oil on the shock threads before you crank down on the spring, if/when you need to adjust the spring preload. The grey threads may be anodized aluminum, but even anodizing wears out eventually. Oil will help prevent that.
Don't put slicks on the wheels. Maybe newer tires with shorter knobs, but not slicks. As long as you're riding a mountain bike, you should be able to take it off the pavement from time to time without risking losing control -- especially if you weigh almost 300lbs, you don't want the tires to wash out if you hit soft dirt while dodging someone on the bike path. Anyway, the rumbling you hear and feel from the knobby tires is wasted energy, and if you're trying to burn calories, wasting energy is precisely what you need to do.
Thank you. I'm going to with a less aggressive tread, maybe a hybrid, just so I don't burn up brand new, perfectly good, aggressive trail tires.
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I like Michelin Country Dry 2 tires; they're $18 apiece, they have a uniform tread pattern from center to shoulder so there's no change in ride feel while leaning, the blocks are short and staggered so they don't buzz very much, and they can handle going off-road a bit.
My previous tires were Michelin Wildgripper Jet, which is still available but with a different name, but the hybrid tread was actually kind of annoying on pavement; smooth in a straight line, very grumbly through corners, because the center tread was made of low-profile chevrons and the shoulder tread was traditional blocks. Might've been a bit more efficient than tires with knobs all the way across, but the change in ride feel when cornering actually made the bike feel more twitchy than it is.
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So, ladies and germs, I went for my first bike ride in 10 years today. Thoughts.
1. Walking the bike a half mile to an autobody shop to fill up the tires was not fun. They were at 30 front and 20 rear. I have them around 50 front and rear for now.
2. Goddamn am I out of shape. I just rode around my neighborhood a bit. Got an Italian Ice for dinner. My bum knee is tender me and my quads are burning like they used to when I'd go out in college to drink and dance with girls until 4am.
3. I can live with the tire buzz. I cannot live with the rear shock creaking like a distressed piglet with every pump. I should send that eBayer a buy it now offer just so I can get that rear spring here sooner.
EDIT: He offered me $45+14 dollars shipping for the spring. Is that a good price?
4. My ass. Mother of god my ass. That seat somehow makes me sit on only bone, and I have a gargantuan ass. I'm going to get a gel seat cover for it for now, look into seat options later maybe. I plan on riding with my girlfriend, who will be riding a beach cruiser around a summer vacation neighborhood. I can't. I just can't.
5. I'm going to have to learn how to adjust the shifters. There are a few gears where, when I put my full weigh on the pedal, it will just skip right off and I'll drop. Every time I do it I think I've broken the chain. And when I was first riding, it refused to go into Crank-3. It will now though with no issues.
5a. Is it bad that I want taller gearsets? It's very level here, as opposed to where I grew up, and I found myself in 3/8 wanting more gears. At home this is perfect. Here, everything is flat and I kind of like the speed.
Well, I'm sweaty and grimy and Eureka is on at 9, so it's time to hit the shower. All in all, I really forgot how much fun riding a bike is. Maybe it's time I take my MSF and get a motorcycle license too.
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4. You're supposed to sit on only bone. Putting pressure on soft tissue cuts off blood flow. Get a wider seat if you need it, but not a pillowy cushy seat with tons of foam. I like the WTB Team XC seat. Very comfortable.
5. If the chain is falling off the gears, that's not so much a problem with the gears as with the crankset. You're flexing it and pulling the gears out of alignment for a split second. That is, unless you hear chattering when you're pedaling normally, in which case the derailleurs really are out of alignment.
5a. It's not bad to want taller gears, but it *is* hard to achieve on a mountain bike. 46 teeth in front is pretty much the limit unless you want to get rid of the front derailleur and use only a single chainring. (that *is* a valid option, just keep in mind it will reduce your ability to climb steep hills.) Blackspire makes chainrings in pretty much any size you want, which makes it easy to customize gear ratios.
If you really want speed, a road bike is the only way to go. They're just so much faster it's unreal. Of course, you'll kill yourself if you have to dive off the path to avoid hitting someone, because they have no traction on soft ground and the brakes are soft squishy crap (you know the kind) compared to mountain bike brakes. Such is life, there are always tradeoffs.
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Alright, getting the rear spring shipped soon hopefully. What do I do about the front spring? Do I leave it soft or should I stiffen it up some too?
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Yes, as it also supports the weight of the rider and the front end will dive excessively or bottom out if overloaded.
Here's K2's recommendations for the Crosslink from the manual:
Rider Weight (lbs) Spring Rate
up to 140 175
130-170 200
160-200 200 (Standard as shipped I believe)
190-230 225
over 230 250
Col.
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Yes, as it also supports the weight of the rider and the front end will dive excessively or bottom out if overloaded.
Here's K2's recommendations for the Crosslink from the manual:
Rider Weight (lbs) Spring Rate
up to 140 175
130-170 200
160-200 200 (Standard as shipped I believe)
190-230 225
over 230 250
Col.
Thank you. I think I have a stiffer front spring than I thought. It doesn't sag like the rear. Leaving it alone for now. Still can't wait for my rear spring to get here. Biking along.... creak-creak-creak-creak-creak.
I had the bike looked over by my local bike shop today. And yes, I bit the bullet on a hybrid seat and street tires. They've got enough tread to get me through grass if I need to swerve around someone off trail or cross a grass field, but not much more than that. Long Island is devoid of unpaved trails so these really were the ticket. New issue though. They diagnosed my chain falling off issue. Looks like the middle chainring is bent, which is why, when I get on it on the middle chain ring the chain pops right off. Small and large chainrings seem to be fine though. Any suggestions? Maybe someone has, or can direct me towards, an appropriate used crankset.
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They diagnosed my chain falling off issue. Looks like the middle chainring is bent, which is why, when I get on it on the middle chain ring the chain pops right off. Small and large chainrings seem to be fine though. Any suggestions? Maybe someone has, or can direct me towards, an appropriate used crankset.
Why didn't they just replace the chain ring?
Or DIY! unless the crank is damaged as well?
I've even taken a bent alu granny ring off, hammered it flat and returned it with no issues.
If replacing it, you just need to know the No of teeth (although you can go up or down a couple if you want) and the BCD.
http://sheldonbrown.com/gloss_bo-z.html#bcd (http://sheldonbrown.com/gloss_bo-z.html#bcd)
Also, check that none of the chain ring teeth or rear cassette teeth are badly "shark toothed" i.e. worn out, as this will also cause a slipping chain and finally make sure that the derailleurs are set up correctly, check out Sheldon or Shimano for instructions on this as well.
Now, enough with the excuses! get it sorted and get out there and ride it! <GRIN>
Col.
[/quote]
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They diagnosed my chain falling off issue. Looks like the middle chainring is bent, which is why, when I get on it on the middle chain ring the chain pops right off. Small and large chainrings seem to be fine though. Any suggestions? Maybe someone has, or can direct me towards, an appropriate used crankset.
Why didn't they just replace the chain ring?
Or DIY! unless the crank is damaged as well?
I've even taken a bent alu granny ring off, hammered it flat and returned it with no issues.
If replacing it, you just need to know the No of teeth (although you can go up or down a couple if you want) and the BCD.
[url]http://sheldonbrown.com/gloss_bo-z.html#bcd[/url] ([url]http://sheldonbrown.com/gloss_bo-z.html#bcd[/url])
Also, check that none of the chain ring teeth or rear cassette teeth are badly "shark toothed" i.e. worn out, as this will also cause a slipping chain and finally make sure that the derailleurs are set up correctly, check out Sheldon or Shimano for instructions on this as well.
Now, enough with the excuses! get it sorted and get out there and ride it! <GRIN>
Col.
[/quote]
Not to worry, I've been riding it. I'm way out of shape, but I rode it over to the bike shop yesterday (which is why I didn't bother with having the bike down more than I needed) and then up to dinner last night. I'm only on the street now, so I only use the third chainring. Short 4 mile trips, just easing my body back into it. I'm itching to take the 9 mile round trip down to the beach soon, but that's going to be a full day.
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Phew, I took a 14 mile ride yesterday and an 8 mile ride today. My legs are SO pissed at me right now. However, I did get that 750lb rear spring today after I got home. I popped it on, went for a test ride. Not exactly what I'd want on a trail, but on the street? It's perfect. Bounce is mostly gone, the bike doesn't droop nearly as much, there's no longer the sense that the suspension has to catch up when I ride up a hump or a sidewalk.
However, I may be putting this bike back to stock for when I move back to an area with good trails. I'm SORELY tempted to pick up a hybrid for the longer gearing and taller tires now as a pavement bike. I can't convert my bike into a 29er, nor can I put a 48t chainring on it. I have a CF swingarm and chain clearance is already tight.
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Well done and keep up the good work!
It's the getting out there and riding that's important, not on what, where or how!
<GRIN>
Col.
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The spring pressure is dependent on your weight, not the riding conditions. You DON'T want a significantly softer spring riding on trails, or you'll bottom-out the suspension on every big bump you hit, and you'll break the shock.
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I went for a long bike ride once. And then it was 90+ degrees for a month and a half and the bike sat. And then one day (today) it was nice out after work. So I went for a bike ride. And sheared a goddamned pedal off.
(http://i353.photobucket.com/albums/r365/lsxjunkie/IMG00922-20120730-1831.jpg)
Time to get new pedals, a middle chainring, and a tire pump. Suggestions please.
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Hi there
My tuppence worth
Bin the current cranks get second had good brand cranks 4 or 5arm type you need stiffer set up than you have,
Think about BB might be about knackered anyway square drive or ISIS but must be rebuildable.
Two rings at front 46t if it has clearance 44 was standard
34t middle ring,
you are big lad you won't need granny ring its quicker to push at low speed and less balancing get good quality NEW rings
Pedals DMR V8 good reviews rebuildable
Above all strength is what you need in your drive train
Hope this helps you
Pete
PS 9degrees C here
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Hi there
My tuppence worth
Bin the current cranks get second had good brand cranks 4 or 5arm type you need stiffer set up than you have,
Think about BB might be about knackered anyway square drive or ISIS but must be rebuildable.
Two rings at front 46t if it has clearance 44 was standard
34t middle ring,
you are big lad you won't need granny ring its quicker to push at low speed and less balancing get good quality NEW rings
Pedals DMR V8 good reviews rebuildable
Above all strength is what you need in your drive train
Hope this helps you
Pete
PS 9degrees C here
Thanks Pete! Any idea where I can start ordering this stuff and what it should cost me?
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Hi there
I'll give you a few wee tips do lots of research before you buy anything
online MBR good for reviews weight weanies etc
and from fellow cyclists in your area and Local Bike Shops
I would not pay more than half new price for used parts
Which can be picked up online (the bay/pink bike/ Craigslist etc)
look out for New Old Stock, next years models will be hitting shops about now bargains to be had.
Ask around and take your time
Ask fellow bikers if you can try out their set ups or borrow their bikes
Pete
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Hi there
I'll give you a few wee tips do lots of research before you buy anything
online MBR good for reviews weight weanies etc
and from fellow cyclists in your area and Local Bike Shops
I would not pay more than half new price for used parts
Which can be picked up online (the bay/pink bike/ Craigslist etc)
look out for New Old Stock, next years models will be hitting shops about now bargains to be had.
Ask around and take your time
Ask fellow bikers if you can try out their set ups or borrow their bikes
Pete
Would this http://www.ebay.com/itm/NEW-FSA-Gossamer-Crankset-BB30-170mm-36-46T-Bearings-/280939118801?pt=Cycling_Parts_Accessories&hash=item416946c0d1 (http://www.ebay.com/itm/NEW-FSA-Gossamer-Crankset-BB30-170mm-36-46T-Bearings-/280939118801?pt=Cycling_Parts_Accessories&hash=item416946c0d1) or something like it be what I'm looking for? FSA Gossamer, 46/36. I really don't know anything about bike components and I'm not looking forward to setting the shifter up for it at all, as I've never done anything like that before.
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Hi there
Those cranks are for a road bike they might just clear swing arm at full droop I'm not sure they are also external Bottom Bracket bearings not sure about chainline,
ideally the middle ring at front is in line with middle of rear cassette.
Oh you may prefer 175mm or longer cranks as your are tall.
Looks like you need a bit of local help/advise.
Here's a good site for DIY bike repairs
http://www.parktool.com/blog/repair-help (http://www.parktool.com/blog/repair-help)
For good ideas/info
http://sheldonbrown.com/home.html (http://sheldonbrown.com/home.html)
Hope this helps
Pete