When to replace a crank?

[ZenSojourner]

How do you decide when you need to replace your crank?

Note that's NEED not want.

[DirtDiva]

When you see a better one for a really good price?

Generally, you just replace the parts of the crankset as the wear out. Chances are the bottom bracket will go first (unless you only ever ride in perfect weather) - usually there are squeaky noises and wobbly feelings giving you a clue here. Then you might wear the teeth of one or more of the chain rings to the point where replacement is a good idea. The crankarms themselves very seldom wear out, even if they can get pretty scruffy looking as the paint/anodizing wear off.

When I replaced the crankset on my mountain bike, it was because I had been chewing through isis bottom brackets at an alarming rate (like, less than three months) in the British winter and wanted to try a different system to see if it would be more durable.

[OakLeaf]

What's wrong with it now that makes you think it might need to be replaced?

I think at one time or another I've worn out or broken every component except for the cranks...

Oh, okay, the cranks and the stem.

[DebW]

The chainrings need replacing if the chain won't sit down in the valleys between the teeth.

[ZenSojourner]

I'm buying this:



And the guy at my LBS wants to replace EVERYTHING on it.

I just want to replace the rear cassette and the chain. And the seat. And the pedals. And the tires. And the bartape.

The components were all new in 1998 (crank, rear cassette, both derailleurs, STI shifters), the frame is from 1987 or 1988 (it's a Terry Despatch, lugged steel). Left shifter replaced in 2004. It has a Sun wheel on there. Actually what I'll probably do is buy a new wheel with a new cassette on it and use that one permanently mounted on a trainer (depending on the trainer, if that's appropriate)

The guy at the LBS is a gonzo mountain biker who replaces all his components every year. I just don't think that's appropriate in my case.

Owner says it shows "some wear" but it has less than 2k miles (on the chainrings)

I actually don't know if the bottom bracket was replaced when the crank was replaced. If not, after 20 years I'm sure it needs to be replaced by now.

$225 is the asking price. I don't see many used Terry's in my size.

[uforgot]

That bike is going to be a beauty! I like those cranks. Some of the newer ones just look ugly and flat to me. I'd listen to Deb. I'm not even close to expert, but why on earth can't you just replace the chainrings? I've noticed that some shop owners just don't care for the older bikes, and only want to deal with new new new, and others like them like we do. Can you find one who thinks that it's a lovely bike and doesn't want to take away it's character?

[ZenSojourner]

Two bike shops in town, the other one is owned and overrun by racerati. They're the guys who think a slow beginners ride is 20 miles @ 15 MPH. Blew me off both times I've been in there.

This guy worries me a bit - when I told him that Terry recommends cold setting and realigning if you need to spread the rear triangle (I had initially considered going from a 7 to a 9 speed cassette) he very nearly laughed and told me "most" mechanics would do that with a big piece of pipe.

I'm pretty sure whacking something with a piece of pipe to spread it isn't "cold setting".

Plus this desire to replace absolutely everything on the bike is way overkill IMHO. He was even trying to talk me into Campagnolo shifters to replace the (as far as I know) perfectly good STI levers on there. Also tried to talk me into going with a compact double crankset to replace the triple on there. Sheesh! He hasn't even seen the bike (neither have I, for that matter)

On the other hand he did back down when I didn't want to go along with an entire refit.

[OakLeaf]

Your LBS owner probably can't get the NOS parts that might be needed to refurbish the bike. That's why he wants to replace everything.

NOS parts are available at a few specialty sites online. The particular parts you'd need may or may not be available. Obviously bike shops generally will not want to install parts that you bought yourself, but if you talk to the wrench ahead of time, they may be willing to (1) let you know what you actually need and (2) install it if and when you find it. Unfortunately it doesn't sound like you have the kind of relationship with these wrenches that it would take to do that.

All the bearings will need to be re-packed, but that's not a huge deal. I don't know why the BB would automatically need to be replaced if it's got that few miles on it and wasn't ridden loose.

[DebW]

If this is 7-speed, then I can understand his recommendation if your 7-speed STI shifter is worn out. You can no longer get 7-speed STI shifters from traditional sources, so would have to replace it with 8 or 9 speed and then upgrade the cassette to 8 or 9 speed. If you upgraded to 9-speed, you'd find the spacing between the chainring too wide for the new chain and need to replace the whole crank too. But if the STI shifter is fine, all you need to do is put on a new 7-speed cassette and chain (assuming those are needed). If the shifter is bad, ask for 8-speed, because 7 and 8 speed chains are the same and your crank would then not need replacing (unless it is really worn out).

Oh "whacking something with a piece of pipe to spread it" is cold setting. Actually not whacking with the pipe, but pulling with the pipe. Cold setting just mean bending steel without heating it. But I wouldn't let any bike shop guy do that. If you want to spread the rear triangle, take it to a framemaker with a jig who can align the dropouts correctly after it's spread.

[Tuckervill]

I wouldn't do a THING to that bike except tune it up and ride it. Wait until something breaks. Don't fix it if it ain't broke!

Karen

[OakLeaf]

I wouldn't do a THING to that bike except tune it up and ride it. Wait until something breaks. Don't fix it if it ain't broke!

Karen

If the bearings have never been re-packed, the grease is now 20 years old and almost certainly not doing its job. BBs, hubs and headsets will last a long, long time if they get a little attention every so often and are kept in proper adjustment, but riding with dried-up grease is a good way to wear them out very quickly.

If you haven't seen (and ridden) the bike, you're really jumping the gun. It may not need anything but fresh grease, tires, cables and housings. It may need a lot.

[Tuckervill]

Yeah, I would include greasing the bearings in the tune-up. But I do my own work.

Karen

[Triskeliongirl]

Rather than buying this bike, why not just pick up a used terry 9 spd. Tons come up on ebay or at the terry website, in the ~$300-400 range.

There is a problem to find 7 speed replacment parts, and upgrading it to 8 or 9 spd may cost as much as just buying a used 9 spd (I KONW all 2001 and onward tery bikes are 9spd, possbily earlier ones too just not 100% sure). Just pick up a used 2001+ symetry.

[Triskeliongirl]

If your heart is set on this bike, just buy a NOS 7 speed casette and chain and do it yourself. Replacing a casette and chain are trivial:

http://cgi.ebay.com/NOS-Shimano-Hype...16136010r28369

Even if the bike is 20 years old, the bottom bracket may not need replacement, its got more to do with miles of wear than absolute age.

[ZenSojourner]

Rather than buying this bike, why not just pick up a used terry 9 spd. Tons come up on ebay or at the terry website, in the ~$300-400 range.

There is a problem to find 7 speed replacment parts, and upgrading it to 8 or 9 spd may cost as much as just buying a used 9 spd (I KONW all 2001 and onward tery bikes are 9spd, possbily earlier ones too just not 100% sure). Just pick up a used 2001+ symetry.

I actually already HAVE a Terry with a 9 speed rear cassette - 2006 Madeleine which I bought new in 2006.

Symmetry vs Despatch - geometry's not the same. Plus this bike is only $225, plus plus I almost never see anything this small for sale. 19" + bikes come up fairly often, this is nominally a 17.5", actually 17". They changed the way they measure the frame size later, so it's a little bit smaller than a 17.5". Which is great because now I get a shot at a slightly shorter top tube without losing that much in other aspects of the bike.

I would probably have trouble finding replacement shifters for 7 speed, but I don't really think those are going to need to be replaced. It's had 2k miles put on it since they switched over to STI, and one of the shifters has already been replaced in 2004. I can get any of several 7 speed rear cassettes if I need to.

Plus plus plus this is 7 miles from where my son lives in NC, and he's coming up to see me next week. When the universe calls, I figure I ought to answer, LOL!

It's just this gonzo mt. biker guy who runs the bike shop I go to seemed a bit overly enthusiastic about rebuilding the entire bike so he sort of had me a little worried with his "oh you change ALL YOUR COMPONENTS every year" kind of attitude. Plus he was steering me towards the most expensive components - like Campagnola triple, Campagnola shifters, etc. Road triples, for some reason, cost more than mt. bike triples, and they're not even as nice (IMO, as far as getting those low gears). There are mt. bike components on this bike, as well as on my Madeleine. Sticking with Mt. bike components if I should need to replace for cause would save me several hundred dollars. Except for the shifters of course, though there's always the possibility of going to flat bars and turning this into a hybrid if it came to that.