k_randomfactor

Greetings all.

I apologize for another chainline question, but my search turned up bupkis.

I just swapped the crankset on my 89 Fuji Saratoga (rebranded for the Backroads Co.) from the stock Suntour XCE 28-38-48 to a modern Alivio 22-32-42. I used the recommended 113mm BB, and stayed with (for now) the stock Suntour 12-28 cassette with 128.5 rear spacing.

The chainline is straight at two cogs outboard, ie: with the middle chainring, not the middle #4 cog, but the next to smallest #2 cog. I used the recommended 113mm BB to acheive this result. I swapped in a 107mm BB that I had out of another bike, and the 3mm gain helped, but not enough. I would just go to an even shorter spindle length, but the crankset is now within 1mm-ish of the BB, and I don't have the room.

I was planning to eventually set the rear to 135mm and change wheelsets, but not in the immediate future.

So short of major surgery and cash outlay, any suggestions would be greatly appreciated.

Thanks in advance.

mrrabbit 

Hardly anyone has a perfect chainline...

What's important is that you try to go with published specs - which usually gets it close - and then keep it that way. In other words - don't make it worse.

If on a 7-speed rear, the best you can do is the 3rd smallest cog - #3 in from the dropout - then that's good enough.

Best way to achieve this is:

1. With 7-speed cassette - freehub cassette stop to end of lock nut = 39.00mm - drive-side flange center to end of lock nut = approx. 45.0mm-46.0mm.
2. Install crankset with recommended BB - step down a few millimeters if necessary - but clear chain stays by at least 1/8-1/4 inch.
3. Of course, ensure wheel is properly dished (rim centered between lock nuts) and then install wheel itself centered between the chain stays.

On my Tommasini with Chorus and Daytona 10-speed, my chainline is right about cog #4 from the dropout - lower than the middle.

=8-)

cny-bikeman

This is the key - the "modern" crankset assumes a matching rear spacing. As you have found chainline is typically more controlled by the rear triangle and cassette/freewheel. I don't see any reason you cannot help the situation somewhat by getting a longer axle and adding spacers on the left side. That would actually allow you to reduce dish as well. I would think it best not to go all the way out, as you don't want to add too much cantilevered stress to the axle, but you should be able to at least gain a cog's worth that way.

k_randomfactor

Many thanks. That's about what I figured.

I'll try the longer axle/spacer for the nonce, and plan on a new wheelset a little sooner than I expected. I'm gonna do a 700c conversion at the same time. Might as well.

Much appreciated.

Bill Kapaun

I would think with your gearing, you'd be spending a lot of time on the smallest cogs?
42T big ring & 12T smallest cog is only 3.5:1 gear ratio.
You may be better off with the 113mm BB and have a better chainline for the most used gears.
In any case, I wouldn't be overly concerned.

k_randomfactor

Actually...

At the moment, I'm a pretty weaksauce rider with iffy knees, a lifelong smoker, just got out of Clyde territory, and we have plenty of hills 'round here that kick my butt. I tend to stay in the mid-range front and back and spin my little legs off. I actually swapped down to the mtn crank because the 28-38-48 that came on the bike was a little too tall for me at my present skill/conditioning level. Moderately embarassing to admit, but there you have it.

Also, this bike was bought with the express purpose of being a tourer, and I know I'll need the low range for that.

I'm currently re-building a Trek 728 with half-step plus granny (28-45-50) for a little "go faster" when I want it. Kinda have the hankering for a c&v road bike too, but that'll have to wait for the cash to equal the desire.

Bill Kapaun

Don't feel bad!
I'm 65, have emphysema, a bad knee and back.
My 2008 Specialized Globe came with the 28-38-48 and an 11-32 cassette.
I now run 22-32-36T 165mm cranks with a 12-23 cassette. I don't use the 36 unless I have a tailwind!

mrrabbit 

Good Lord!

I almost never use my large chainring on my Chorus double. My buddies will tease me, "Hey Shack, if you don't want it, I'll take it!"

And I'm ONLY 44...

=8-)

k_randomfactor

38

But as someone once said, "it ain't the age, it's the mileage."