pierce

ugh. just swapped my crankset on my Specialized Globe Vienna 02 (think base model Sirrus and you're pretty darn close), from the fugly stock Shimano M191 (Tourney grade, I think?) to an Origin8 Trekking Pro... both square shaft.

The Origin8 is sitting much farther from the frame, such that I had to readjust the front derailleur all the way to its outer limit of travel to get it to shift. Meh. The chainline is all whack, in the middle ring, its about aligned with gear 7 of 8

... yes, I thoroughly cleaned the BB shaft and greased it quite well. I torqued the new crank bolts down about as hard as I could with a long arm allen, but I didn't break out my ratchet hex bits from my motorcycle toolset....

the teeth on the middle ring are sitting just about exactly 54mm from the centerline of the frame.

does anyone know what the 'standard' chainline offset is for a 3x8 700c hybrid ?

badger1

pierce,
I think you'd get much more accurate responses on the 'mechanics' board, but fwiw I'll hazard a rough guess. I'm assuming your Globe has 135 rear spacing?

Did you change out the b/b? If not, you might be able to measure what's on there re. axle length, and drop down a little, e.g. 118 to 112. You should be able to do this; I think Shimano's mtb/trekking centre line is about 48 -- that may be the problem. But again, caveat: I'm no mechanic, and I did not stay in a Holiday Inn last night, but I think axle length is the problem.

pierce

I did not change the BB, just the cranks.

and yes, its a mtn based group, and has 135mm rear spacing. I guess I'll have to pull the cranks off to measure the BB length, if I can find my dial caliber (and if the arms on said caliber are long enough...)

found the shimano tech sheet on the M191 crankset (listed under 'non-group components', hah), and its chainline is meant to be 47.5mm with a 122.5mm spindle. so I'm about 7mm too far outboard, and would need a 108 or 110mm spindle?!? phew.

I also found a table on Sheldon's site that listed the Altus crankset as using a longer BB than most anything else :-/

badger1

Sounds like that's the issue then; you should be able to purchase a really nice b/b with an appropriate axle length, and pull that puppy inboard! That's what I'd do ... your Globe as you currently have it is a really nice bike -- well worth the investment. Me, I'd be nuts enough to buy an SKS or Phil's b/b!! Example: I couldn't stand the thought that my Sirrus had one of those awful 'ball bearings in a retainer ring' headsets, so I replaced the whole thing with the appropriate full cartridge bearing upgrade after less than a year!

pierce

I'll probably get a UN56 or similar BB, those are just fine. I suspect it has a UN26 in it now, its not cone-and-cup at least :rofl:

Bill Kapaun

Did a similar swap on my Globe to get shorter cranks.
Same problem going to a FSA Alpha drive? crank. I couldn't quite reach the large ring without SEVERE chain rub.
Had to go to a 113mm cartridge, IIRC.

pierce

p.s. this is the crankset in question...






which, IMHO, is a nice improvement over...

pierce

even tho I have relatively short legs (30-31" inseam, and I'm 6' tall), I've always preferred slightly longer cranks. I do have large feet (size 12), maybe that has something to do with it? I try and flex my ankles to extend my leg stroke while pedaling...

Bill Kapaun

I'm an inch shorter and 1 shoe size larger.
Thing is, I have a bad knee and to avoid knee pain, it's 165MM.
Since I had a titanium "nail" inserted in my tibia through the same bad knee 6 weeks ago, I'm hopeful I'll even be able to ride again. I saw the surgeon today and he said I "MIGHT" have additional permanent "stiffness".

However, crank length ISN'T your issue. Too long of a bottom bracket is.........
You need to find out what the recommended length is for your new crank.

pierce

yeah, I emailed Origin8 but not holding my breath. Their webpile is remarkably content-free. I think I'm gonna go by measure twice cut once

badger1

Honestly, pierce, I think you can get close enough ("for jazz") with calipers/careful measurement. Shim. UN56 is a great choice.

Re. crank lengths ... it's interesting how we each of us have 'ideal' lengths, contingent on personal physiological factors ... the 'standards' really don't cut it.
I e.g. have long legs for my height (84 cm. true cycling inseam @ 174.5 cm height), but don't get on with what would be 'standard' 172.5 or 175 cranks for my leg length; I use 170s. Any longer, and I get problems with my (old and arthritic) hip joints from having to come too far up/over the top, in part because I'm one of those who naturally pedals "toes down". Learned that from my sports medicine guy (who happens to be a cyclist), .

no1mad 

Can't help with this technical discussion at all; just popped in to say that's a nice looking rig you got there, pierce.

pierce

thanks. its been fun building it up. got it in july, when I was recuperating from a broken foot due to a car accident which totaled my old hybrid (bike was on a hitch rack, I was in the passenger seat of the van). its a 2010 Globe Vienna 02 that was being sold as a dealer demonstrator, I got it for the opening bid of $300 plus $50 shipping, bike arrived while I was still in a cast, in virtually new condition.

first thing I did was get some pin pedals for it, $35 on ebay. I recycled the flatbar off my old bike (about the only part that wasn't bent or mangled). ergon gp3 large grips, $40-ish? ... fenders, $40ish at the local bike store. axiom rack, $35 at a LBS. insanely bright chinese LED headlight, $35 on ebay. red tail blinky, $20 at LBS. longer stem, $15 at LBS. tires, $100 at LBS (Vittoria Hyper Randonneurs, ride really sweet). bottle holder, camelback bottle, kryptonite lock, and banjo bros tank bag, ummm, probably another $100 at various LBS stops. Origin8 crankset, $65 mail order. specialized computer, $30-ish at LBS.

so I've spent at least as much on Barbie's accessories as I did on Barbie, ahahahaha.

pierce

as a wrap to this story..

picked up a UN55 110mm BB at a LBS. slapped it in yesterday in place of the stock UN26 122.5mm, torqued on the Origin-8 Trekking crankset, and voila, my chainline is now spot on dead center. on the middle front ring, its right in the middle between #4 and #5 (of 8). couldn't ask for better. all gears shift sweet, only a bit of FD/chain noise in the crossover extremes of both bigs, and small front plus smaller 2-3 rear, none of what I'd ever wanna use. chain is much quieter in all 'normal' gears, the machined alloy chainrings are just that much quieter than the stamped steel ones.

Dilberto

My Bad Boy's chainline is that magical 51mm.....with the FSA Energy 10-speed crankset

pierce

yeah, since I underwent this exercise, i've come to realize chainlines on hybrids are pretty much conventional mountain, at 50-51mm, and road bikes are pretty much standardized at 42-45mm.

the real driving factor is the rear OLD width, and position of the cassette

the other thing I've figured out, via reading bunchs of spec sheets, and demonstrated by this project, different cranksets have different BB widths for the same chainline, which really complicates things.

then, all of this playland of customizing BB axle widths for non-standard crank applications only applies to square taper stuff, the octo kinda stuff doesn't have a lot of choices in BB widths, and the newer 2-piece stuff, you get no choices, so there's no putting a road double on a hybrid or mountain frame, or any such using one of those.

and the availability of larger ring triples and doubles in 135mm OLD land is getting slimmer. I'm probably old fashion, but I like all alloy 5 bolt cranks, preferably ones that are fairly slender. if I get back into better shape, I could see wanting to use a touring triple like a 52-39-30 on my hybrid, but I suppose by that point, I really should be looking at a proper road bike again. I'd also prefer to stick with 3x9 rather than x10 or (shudder) x11.