davidfl

Hello. I'm a pretty big guy. 6'3" about 300lb. I'm looking to bike to work 10 miles away (!) twice a week. The reasons are to help me stay fit and to save some money. Now I'm a big guy and I won't be participating in the Olympics anytime soon but I'm not completely useless. I can walk 7 miles if I have to without resting. I can go about 3 miles in the FL sun without breaking a sweat. I can go up stairs fine without getting winded, etc you get the picture. (I'm only posting this part so as to say I don't think my problem is due to my not being able to pedal a mile)

Long story short I don't have a lot of money so I had to settle with what I could afford around $100. I went to the three pawn shops but there wasn't anything good or what was "good" (acceptable) was just a rusted Walmart bicycle for $150 which sells new at Walmart for $200.

I settled for a Next PX 6.0 at Walmart for about $100 with tax. 26" 18 gears.

(hopefully posting the link is okay. It's just so people can see specs)

https://www.walmart.com/ip/26-NEXT-PX...-Bike/21009334

It works fine on flat ground. At least on the very upper gears. The bike has a gear select of gears 1-6, with +, normal, or - for each respectively on the other handlebar. I have to use "6" and then +, normal or -. If I use 1-5 peddling essentially does nothing. There is very little resistance at all. I have to rotate three turns before I can go two inches it seems. Note that it seems to go into the gears fine. They just don't seem to be actually usable.

Now I found the online specs for the bike and I see it is rated for a max of 230 pounds (this wasn't in the manual that I saw before buying it). So obviously it's not ideal and I should take it back and get another one (such as a 29" which I am reading tends to be rated for 270-300 pounds). I probably will be doing that in a few days. But for now is it probably the issue that the extra 70 pounds is causing the lower gears to be useless or could it be simply that the gears are broke or need some sort of adjustment?

I ask because I'm set to take this bike for the 10 mile commute tomorrow morning. If there is a way to fix it to be more usable that would be great. I'm pretty handy mechanically. I won't be able to take it back until Monday, unfortunately. Not using it probably means I will be walking 10 miles and that will take 3 hours.


Thank you for any advice and for reading.


PS- I DID ride this bike home from the store 5.5 miles in 95 degree heat. (which was a mission!) It worked well enough on flat ground (though it felt that I had to expend more effort than I should) but if there was even a 5 degree incline, forget it. For example I had to walk it up a bridge. But the good news is that six miles of my commute is flat on the beach. So I think I can do this. I'm just not sure if there is something wrong with the gear adjustment which I can fix or if the problem truly is my weight.

DiabloScott

I can't imagine a weight issue causing a shifting problem. The bike's weight rating is really about the strength of the wheels and frame.

Even your lowest gear should be about one wheel revolution for each pedal revolution... and there's no way a (non-broken) cassette will engage in the high gears and not the low gears.

The most likely scenario is that the monkeys at Walmart messed up the assembly.

edit - Oh, I just figured out what you are saying about the gears - the +/Normal/- is the crank and the 1-6 is the cassette - so it works on any chainring and only on the smallest cog. Something sounds broken.

davidfl

Thank you for your reply. I believe you are right. I'm mechanical but not very experienced with bikes, more autos. But it appears something is off with the front derailleur? I am noticing it seems to be staying on the smallest sprocket/gear even when changing it. From a little reading this seems to make sense? If it's stuck on the smallest gear/sprocket in the front then that means it's stuck in a lower gear, no?

So I guess I only have use of gears 1-6 out of 18.

edit: I see now that I think it seems like we said the same things. I'm just not privy to all the terms.

I'm checking out the manual now about how to do a front derailleur adjustment. Hopefully I can get this done.

Nerull

Certainly not right, but how that could happen I have no idea. It sounds like the freewheel isn't engaging, but why would it work in the smallest cog?

DiabloScott

Your front derailleur should be on the small ring when the shifter says "-", middle ring with "NORMAL", and large ring with "+". A common monkey mechanic error would be to not get the cable right and the derailleur won't move far enough to shift... you would notice that your cable is really really loose when your shifter is in the "-" position. You could also tug on the cable with your fingers and see if you can get the derailleur to move over that way as a test.

davidfl

I'm not sure. I think it is the front derailler. It seems stuck on the smallest cog as you all are saying. There are 3 cogs in the front and 6 cogs in the rear derailleur.

I'm reading about how to try to tune the front derailleur. Buyt it sounds like this isn't normal behavior and something else might be seriously wrong with it. As a contigency measure would there be an easy way to force the front derailleur to use the middle cog so that I can reasonably use it tomorrow until I can take it back?

cny-bikeman

I agree with Diablo. Likely the front shift cable is just not properly tightened, so that the lever is not able to move the derailleur. Yes, if you are stuck on the small chainwheel in front (often called the granny gear) then the lower gears in the back with that will not get you going very fast. On the other hand, though hills should go pretty easily. We need to know your city - may be able to direct you to a local resource, either to get some low-cost help with that bike or perhaps assistance finding a decent used bike. $100 is still doable from Craigslist unless it's an unscrupulous "flipper."

davidfl

I am in Daytona Beach, FL. That derailleur does seem to be it. I'm learning a bit about it. I see it is like a little bracket guide and it seems it is supposed to move right and left to guide the chain over a cog. The adjustment nob on that side does seem extremely loose. It could just be that. Let me see about attempting to fix that.

dsbrantjr

I'd suggest that you follow this procedure from the beginning as if you are installing a new derailleur: https://www.parktool.com/blog/repair-...ur-adjustments

Make certain that you have each step right before you go to the next. Here's a procedure for the rear as well:
https://www.parktool.com/blog/repair-...nts-derailleur
The Park Tool site has a lot of great tips for general bike repair/adjustment.

davidfl

Thanks, I tried making some adjustments using the instruction manual which came with the bike but it seems as if basically the lever (shifter) never pulls on the cable at all when it is actuated. I tried tightening the cable and this didn't make any difference. So I wonder if it's just the lever mechanism which is defective?

I notice absent pressure the natural position of the front derailleur is on the smallest cog. It needs "pull" on the cable to move and the lever/cable doesn't seem to be giving that.


edit: I tried adjusting the high stop screw both ways as well but it doesn't seem liek the shifter mechanism is doing anything in that there is never any "pull".

Is there any way to simply force the front derailer/chain into the middle position (gears 7-12) just for tomorrow so it is somewhat usable instead of having gears 1-6??

davidfl

SUCCESS! (sort of) After going through the procedure (tightening the cable), testing the shifter to see better if it was pulling the cable I saw that actually it was just not near enough. I adjusted the high stop screw and then moved the front derailleur adjustment lever (on the handle bars) down HARD and it clicked several times. It then finally moved and I have it over the middle F.D. position now.

I don't know if perhaps my assumption that there was only a +, normal, and - position was wrong and that there were many positions or what (but this hardly makes sens since there are only 3 F.D. cog positions and it isn't mentioned in the manual?). In any event it should be able to get me to work tomorrow so I'm going to leave it alone in the middle position (gears 7-12) for now.

Thanks again everyone.

DiabloScott

You want to adjust the low stop screw... assuming you have one.

I suppose it's possible your shifter is no good, or maybe that your cable is broken or not attached in there.

Bill Kapaun

IF it's a Wal Mart bike, I seriously doubt that the front is indexed. Just a lot of clicks as you go through the range.
There really isn't a need for that anyway.

On this bike I suggest this procedure-
With it on the middle ring-
Screw in the L screw (low limit) a few turns.
Back off the shifter to -.
The low limit screw should prevent it from shifting back to the small ring.
Now turn the L screw back out in 1/2 turn increments until the chain drops back to the small ring. You'll need to spin the crank, so hop on and ride it a few feet. Repeat as necessary.
Turn out 1/4 turn more.
Now- pull all the slack out of the cable with a pliers and reclamp it.

cny-bikeman

If you have truly pulled the cable tight with the lever in the minus position then there's something wrong with the shift lever, not the derailleur. Yes as above you can adjust so the derailleur is in the middle gear but it will probably not go out far enough to avoid rubbing in some of the outer cogs. Either get it fixed at the place you bought it or take it to a shop. Unfortunately no bike co-ops near you, though there are a couple people advertising bike repair on craigslist - but better to find a knowledgable friend.