DMC707

Uggghhhh ----

Close to new bike time but a potential issue has cropped up ------ crankarm clearance at chainstay looks pretty tight with Campagnolo Record Pista chainset and bottom bracket

Not sure how tight is too tight, but that looks like its very close ---- chainstays are pretty large

Anybody know of any crankset/bottom bracket combos with a little wider Q factor?

I had thought of a little wider bottom bracket, but this picture is of the non drive side -- wider bb would impact the drive side primarily I think

Voodoo76

Don’t know if it’s wider. Measured a 170mm Omnium. From inside of arm to inside of opposite arm 113mm.

brawlo

Is the clearance the same on the drive side? I'm assuming the BB is the kind that you can adjust where it sits in the BB? If not, a wider BB may be an option.

Also worth testing the flex to see how much the clearance might change through the pedal stroke. If there's flex, generally while you're stomping on one pedal, you're pushing the BB across from that side, which therefore means that a little extra clearance will be gained on the opposite side as the pedal passes the chainstay.

CliffordK

Have you tried the bike yet? Experienced rub? Do the pedals mount flush?

I'd probably add a little tape to the chainstays, then try it out. I'm doubting that it will actually rub.

Hmmm.... thinking of cycling dynamics (standing). When you push down on the pedals, you pull up on the bars, and push the frame away from the pushing pedal, and towards the pulling pedal.

That should mean that any frame flex should flex away from the pulling pedal, but at the same time one might be pulling at an angle slightly towards the stay.

Anyway, I think it may still be a wash.

If you're too concerned, you could dimple the frame, or have it dimpled. It wouldn't take much since you already have positive clearance.

fietsbob

A , BB spindle longer on the left end*, or B another crank-arm that is not so straight
get the ones from Campag's newer.. square taper Road cranksets perhaps?

*Phil Wood press fits the spindle in the bearings , its adjustable... I have Pulled the axle thru , and so changed the centering..

DMC707

Its roughly the same --- I specce'ed 29'er MTB size chainstays ---- afraid of messing with the chainline too much on the drive side though .
The bottom bracket is a cartridge bottom bracket, --- a spacer may be able to be added to it , but that would just pull it in tighter on the opposite side




Actually haven't tried it yet --- was almost afraid to, --- but wrapping it with tape may be the trick to see how close it is actually getting

---- The framebuilder mentioned dimpling it ---- Its already dimpled for chainring clearance , --- but I do recall the days of oversize aluminum tubing, seeing bikes from Cannondale and Klein with dimples both at the chainring and the crankarm, so its definitely not unheard of






I've never seen a 165mm road crankset in the flesh, I've looked for them though --- but I will check on that Phil Wood alternative

carleton

If I recall correctly, the Campy Pista BB is 109mm. I think there is also a 111mm Chorus (?) BB available as well. That may be the cleanest solution. There are also some non-Campy options as well that are like $25. Try Ben's Cycle's website to see options. Or Retro-Gression's website.

Also, this issue comes up on some LOOK 496 using Dura Ace cranks. I had to use 1mm spacer on the drive side BB cup during installation. That might work for Campy as well.

But, that being said. If it clears, it clears. You'll know if it's gonna nick the frame or not.

Then there's always a file to the cranks or a ball peen hammer to the frame

Clythio

111mm long axle? If positive, buy a 115mm Campy and be happy.
Already 115mm?.. hard to solve.. FSA Carbon track with wider ISIS axle is the biggest Qfactor solution available. Had to use it on a Cobra carbon frame.

700wheel

For a year I rode a Leader 735TR* paired with a 80s era Campagnolo 165mm crank set (which is still in active service). There was around 2 mm clearance between the crank and the chainstay; I was worried at first ans thought about filing the crank or denting the chainstay. In the end I just rode it and never had a problem. Try it out to see if you have a problem.

If you do buy different cranks check the the Q distance minus twice the local crank thickness to ensure more clearance.

I've also seen bikes where the chain ring interfered with the chainstay.

* I liked the leader except it had aluminum alloy rear drop-outs which the track nuts gouged up. It rode very well on the LA Velodrome.

Baby Puke

Phil Wood can do custom BB spindle lengths.

tobukog

You might want to check out the heel clearance while you're at it.

fietsbob

Pulling spindle. 2 lock-ring spline mounting tools stacked on 1 end, washer across ,

crank arm fixing bolt turned , does the pulling , spindle rotation resisted with an adjustable wrench on opposite end..

I used hand tools .. to recenter mine.

Goal: drive side chain line unchanged , non drive side , longer..




....

DMC707

Update: Crisis averted

Sugino 75 crank/bottom bracket combo is wider than Campy! With the downside of course being that it doesnt look like Campy .

I robbed the Sugino off of my old Waterford for test purposes, and reinstalled the campagnolo crankset/ BB on the Waterford and it is equally as tight on that frame.

I guess the Italians really like slim chainstays

carleton

Awesome!

Pics?

rustymongrel

I had this same issue with my self built steel frame and record cranks. The short chainstay length and straight chainstays had very little clearance. I tried a Chorus BB and it didn't help things at all so I suspect the pista BB is 111mm.

As far as I can tell the record pista cranks and BB are the narrowest out there when it comes to off the shelf track cranks.

DMC707

After obsessing over chainlines and crank clearances for the better part of the day, the only pics I thought to take were of the schooner of pilsner from the local German pub I quaffed afterwards


This is the Yin and the Yang of being a Clydesdale sized athlete I'll get some pics up in the new track bike thread when this baby is ready to roll out though ------ Since the closing of the Superdrome, - I will be travelling to St Louis to try this out on their track I think pretty soon -- besides Houston it is the next closest , --- then from St Louis, Major Taylor is within striking distance if I have enough time on my hands !