77midget

Well, I needed to top off my hill day the other day. Today, had an afternoon meeting at another building 12 miles away from mine, so after biking in this morning, I biked another 12 at lunch to the other facility. When the meeting was complete, I had another 8 or so back to my house, with another steep hill on it that I have heard other bikers lament, and often see people walking it. Well I made it up, even it in 2nd to last granny!

However, 1/2 way up, when I shifted to the smallest chainring, the chain jammed somehow, and I had to stop. I managed to get it sorted and on the small ring, and managed to get back on and pedaling, and thought everything was fine. On the next big one closer to my house, when I shifted down to the middle ring, I heard a bad clicking. When I went to the low ring, more out of curiosity than need, chain jammed hard, and I had to pull over again. WTF!!!!

Well, on inspection, one of the teeth on the middle ring was bent hard toward the inside (toward frame). My chain rings look like they are made of multiple pieces of stamped steel. They are original for my Trek 4300 MTB, and the tooth that was bent was at what looks like a seam, and the steel was partwise cracked at the base of the tooth. This was good, in a sense, since it was weakened enough that I was able to bend it straight with my multi-tool.

Has this happened to anyone here? Does my description make sense (for my chainrings)? Is it hard to replace chainrings? Expensive, even for just oem replacements? I am saving for an LHT, and don't want to dump too much into this rig right now.

I am leaving for vacation on Saturday, and the bike is coming with me one way or another. I hope to have it fixed before I leave.

sstorkel

Chain rings aren't that expensive. I would expect a middle chain ring to cost around $20-25 online. A big chain ring might be around $40. They're easy enough to replace yourself. You'll save yourself some headaches if you do the replacement with the chain rings off the bike. Removing the cranks and chain rings may require some special tools.

Sounds like you may also need to adjust one or both of your derailleurs.

77midget

interesting. I am hoping that one of my local LBS can help me out tomorrow with parts, since I am leaving on Saturday.

I will check it again, but the front derailleur was spot on, since I adjusted it a week ago, and have put 100 miles+ on it since. I think something else affected the tooth, and the tooth cause the chain to hop off and further bend the tooth.

Tom Stormcrowe

CHances are good they can....chainrings are common parts to stock, as are cog rings for a cassette.

Did you shift under heavy load, perchance? That's usually the culprit if you bend a chain ring.

Mr. Beanz

Some low end bikes have chainrings that are riveted on. Look at your setup to make sure they are chainring bolts and not rivets. If they are rivets, you're srewt!

Remove the cranks to change chainrings? Hmm! I just pop the chain off the gears and never had a problem.

10 Wheels

Have them put on a Chain Checker. About $10 bucks. It will keep the chain from jumping off the small ring.

77midget

Yes I did, though I thought I let up enough for the shift. I was going up maybe 15%-17% grade for about 1/2 mile.

As for the rivets/bolts, I know that my middle and large rings are bolted, but I think the small is riveted. I am sure that this is a component on my bike that is of the 'lower end'.

I am going to start digging into it soon, after some coffee. My vacation starts today

Mr. Beanz

If the two outter rings are bolted, then the small inside ring should be also. But the bolts are installed from the opposite side of the two outter rings.

77midget

Well, Mr Beanz got me thinking, so I went and reinspected, and they were all riveted. The outer rivets had hex caps on them, purely for look, and that was what initially fooled me. Also, on further inspection under bright light, the rings have some weird, uneven, and heavy wear.

Fast forward, and I brought the bike to my primary LBS, where the bike came from. Their inspection and chain measurement indicate dull drivetrain replacement-crankset, chain, cassette. This explains, and he agreed, why I might be having some issues getting drivetrain adjusted properly as well.
He checked in their storage room, and it looks like he has everything needed and he is going to push hard to bang it out today so that I can still take it with me tomorrow on vacation. They are pretty backed up on tune-ups and new bike deliveries-In the short time I was there right when they opened this morning there were a couple people and a couple calls for bike pickups today, and every work stand was occupied.

Also, he is putting a powerlink chain on for me for easier cleaning. This will help with the slop that I sometimes have to commute in.

Though I am not looking at dropping over $100 into the bike when I am trying to save for a new LHT next year, I am looking forward to my issues being resolved, and I am hoping that it will be a lot smoother and crisper. And I am definitely glad that it happened now, and not on vacation where I would have been sa-crewed. There is a nice 17 mile ride where I am going that I found on mapmyride that I want to check out.

For anyone curious, my LBS is Milford Bicycle (www.milfordbicycle.com) in Milford, MA. I bought the bike there 7 years ago, and my wife's there over 10 years ago. I have never had a problem with their service or products, and though I sometimes go to other places for parts, tubes, or just browsing, my bike goes to Milford. They have been good to me.

So, the clock is ticking for me. They are open til 8 tonight, and he will call me when ready.

bigwies

Good luck on that 77.

I just had the same parts replaced on my bike a couple weeks ago. The actual repair will probably only take around an hour, but if they are really busy it could easily take longer. I had mine replaced on the spot (crankset, bottom bracket, chain and cassette), but I have a really good relationship with the Service Department at Cycle Loft in Burlington. I actually stood and watched the tech do the work. I was trying to use it as a learning experience. I have found that a good LBS will make accommodations for people who commute or have other time limitations. The key is letting them know your situation and being flexible with waiting or leaving you bike and returning later.

Enjoy your vacation.

77midget

They were great with me. Didn't even have to wait. They checked part inventory right away, since I was only going to leave it if they had the parts. I explained my situation, and he was upfront in saying that they were jammed, but that he would fit it in and get it done for me by EOD today.

How was your ride post-replacement?

If I had time, I was looking forward to doing the work myself, but alas. This is just another reason to buy the LHT-I need a spare ride when one is under the knife!!

walter231

Yikes. Where have they been hiding that monster?

btw, bad things often happen changing rings uphill. It might be theoretically possible to do that if everything is properly adjusted and your technique is good, but why risk having to restart on the hill or causing damage? When you change cogs the chain doesn't have to move as far and the chance of dumping the chain is much smaller.

77midget

Well, it was actually adjusted well. I spent 2 hours cleaning and adjusting the drivetrain last weekend. Throwing the chain was actually because of the bent tooth-everytime it came around, it lifted the chain up and in, and off the lower ring. doh!

The hill is in Hopkinton heading toward Upton. The numbers I gave are estimates based on other hills. Mapmyride does not really give a good reading on it, for some reason.

c_m_shooter

Sounds like you were shifting it under load. I destroyed a few chains and cassettes on my moutain bike that way before I learned to get the front shifter on the chainring I am going to need before I start climbing and leave it there. Shifting on the back is usually smoother, so that can be done while climbing if you let up for a crank or two, but leave the front alone.

77midget

well, I was shifting front on the way up, just thought I had eased up enough. Lesson learned

Anyway.....BIKE IS DONE!

They got it done for me in time. The place was packed, but I was still able to pick it up and get out of there nice and quick. The crankset that they had was not the same toothcount as my old one, but he said that, since I commute on it, I will like it more. If I don't like it, or if it doesn't ride right, he said to bring it right back and they will order the other one. He figured that this would allow me to get on the road over vacation and try out the larger chainrings before commuting.

It pedals sweet now! I surprised how much my old gear had worn, but it was used for offroad before, and would have worn faster anyway.

Also, very happy to have the sram powerlink on there now-it will be easier to clean.

The proof will be either tomorrow morning, if I can fit a ride in before the drive, or afternoon once we get to our destination, but it feels good so far.

bigwies

I love a good ending.

77midget

UPDATE-Finally got to put the bike to the road yesterday, riding a 25 mile loop through laconia. I modified my original route once I was on the road, and ended up with some pretty tough climbs, but it was a great ride overall

https://www.mapmyride.com/ride/united...conia/42543178

The new gearing worked great, as I was able to achieve and maintain quicker speeds on the flats while still having the right gearing for climbs. It needs to be adjusted a bit better, but my LBS said to take it back when I get back if there was anything up, so I will let them handle it.

UniversalFrost

yes, sub par or lower end drive trains will break when shifting under loads like in a climb. That is why they make heavier duty gear just for those folks who want to shift under load.

I have Dura Ace/Ultegra on my roadie and has never failed me even when doing a lot of shifting on extreme climbs in the rockies this spring and a not so extreme climb up mt. lemmon in Tucson this summer. For a mtb I would go with a Dura ace chain and xtr cassette and crank and of course the rear dr.

JoelS

You might buy a chain check tool too. Chains stretch. When they do, they cause unnecessary wear on the other drive train components. Check your chain!

I recently had to change my chain and cassette due to that. A new Campy Chorus cassette is a bundle.

77midget

Yeah. I am planning on augmenting my tool collection with some bike specific equipment. As for putting dura ace/ultegra on my bike, the drivetrain would cost more than the bike is worth, tbh. I would rather spend that money on the new bike I plan on buying next year.

The new cranks/cassette/chain have been great so far. I went for another hilly 22 mile ride yesterday. Today, it is rather rainy, and though I am not averse to riding in the rain, this is vacation, and I think I will skip today. Tomorrow, I am going to shoot for something around 30, and if I feel good after that, I might try for my first 50 miler on Friday, or Sunday when I get back home.