Frame alignment issue i dont understand

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Catagory6
Posts: 123
Joined: Thu Feb 09, 2017 2:36 am

by Catagory6

Frame is a ritchey Swiss cross

Did the string test from one rear dropout, around the head tube to the other dropout.

There is a 5-6 mm difference at the seat tube towards the NDS.

The rear wheel is properly dished. Checked with dishing tool, and flipping the wheel in the rear dropouts.

It sits just about perfectly center in the rear triangle.

The shifting is flawless

One thing I can't determine is if the rear wheel is in a straight, parallel, and on-center alignment with the front wheel, or the front triangle.

I've never had any handling issues at high speeds (40mph+). Wobble, shimmy. Very stable handling

Is this 5 mm discrepancy between DS and NDS due to compensating for space needed for chain rings?

by Weenie


Catagory6
Posts: 123
Joined: Thu Feb 09, 2017 2:36 am

by Catagory6

i flipped the bicycle over, took off the wheels. reinstalled the skewers and then tied the string from the center of the rear skewer to the center of the fork skewer (measured between the inside face of the dropouts).

and the string looks like its off centerline of the bottom bracket shell by about 4 mm, with the gap being on the drive side. which doesn't seem consistent with the above string test showing the gap towards the NDS.

i can even see that the chain stays aren't equidistant from that centerline

there's a bike shop about 1.5 hours away that said they would look at it.

DamonRinard
in the industry
Posts: 266
Joined: Fri Apr 29, 2011 8:32 pm
Location: Connecticut, USA

by DamonRinard

If there's no problem, what's the problem?

High strength steel alloys can be risky to cold set. When I worked for Bill Holland, he stopped bending frames and changed to thermally aligning them, adding a pass of weld here and there to pull the frame into perfection. Of course that was before paint.

I would seriously consider not doing anything, just ride and enjoy.
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

Catagory6
Posts: 123
Joined: Thu Feb 09, 2017 2:36 am

by Catagory6

DamonRinard wrote:
Thu Jun 21, 2018 12:27 am
If there's no problem, what's the problem?

High strength steel alloys can be risky to cold set. When I worked for Bill Holland, he stopped bending frames and changed to thermally aligning them, adding a pass of weld here and there to pull the frame into perfection. Of course that was before paint.

I would seriously consider not doing anything, just ride and enjoy.
that's basically what my local shop said to me.

i'm just curious as to what's going on with this frame. maybe there IS a problem that i'm just not aware of? could be the reason i'm doing my local hill-climb in 17:12, instead of 14:38?

ya never know... HA!!!

Zakalwe
Posts: 440
Joined: Sun Jun 17, 2012 3:15 pm

by Zakalwe

What made you even look for any sort of discrepancy?

alcatraz
Posts: 972
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Are you suspecting that both dropouts have "traveled" laterally by 5-6mm?

Has the frame ever been in an accident?

Can you ask the frame builder if this is correct or not?

I don't think setting the frame up in some kind of jig and moving the dropouts by 5mm will damage the frame but you also won't get any free speed by doing so either.

/a

kode54
Posts: 1211
Joined: Tue May 23, 2006 9:39 pm

by kode54

could it be asymmetrical? and isn't there some dropouts with either a 130mm or 135mm width?
- AX Lightness Vial EVO D + DA9150 + Enve SES 3.4 carbon hubs
- Parlee Altum + DA9150 + Enve SES 4.5 carbon hubs
- Parlee ESX + DA9150 + THM SRM PM + Enve SES 6.7 CK hubs
- Independent Fabrication Ti FLW + DA9100 + Enve 3.4 CK hubs

Valbrona
Posts: 1488
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

If the OP is reporting a possible frame misalignment issue at the back - wheel not lining up straight - the only thing I would advise is having the frame checked with dropout alignment gauges.

If it is badly out and the frame is new you make a warranty return, but if older you have the droput(s) properly aligned - assuming, possibly wrongly, that the Ritchey Cross is steel.

wingguy
Posts: 3962
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

Catagory6 wrote:
Wed Jun 20, 2018 8:15 pm
and the string looks like its off centerline of the bottom bracket shell by about 4 mm, with the gap being on the drive side. which doesn't seem consistent with the above string test showing the gap towards the NDS.
So the wheel sits in the bike perfectly, the bike rides perfectly, and the two different 'tests' you have tried have given you two completely different answers?

Do you not think the most likely answer is that the frame is right and you've tested it wrong? :noidea:

by Weenie


2lo8
Posts: 440
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

The front triangle can still be off and the dtivetrain will work perfectly.

I'm honestly not sure what the second string test is, but it sounds like the string is resting on the bottom bracket shell. It could be explained by head tube twist, maybe the fork not being straight, skewers not seating in the dropouts and the BB shell itself being angled and pushing the string. The string should have only two fixed points of contact per run to be worth anything.
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