Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Bicycle Mechanics (https://www.bikeforums.net/bicycle-mechanics/)
-   -   Spacing from cassette to frame (https://www.bikeforums.net/bicycle-mechanics/1137550-spacing-cassette-frame.html)

gnrboyd 03-05-18 10:36 PM

Spacing from cassette to frame
 
2 Attachment(s)
Bike: 2014 Trek 7.4 FX Hybrid

I just replaced my Shimano rear axle set with a generic axle set from my LBS. The axle has cones that are 1.5 mm shorter than the originals (13.5 mm vs 15 mm each) and a spacer that is 3 mm longer than the original (14 mm vs 11 mm). This caused the rim to move closer to the drive side which meant I had to re-dish the wheel. After doing so, I realized that the cassette is now closer to the frame.

From what I understand, it is preferred to get the cassette as close to the frame as possible to minimize the amount of dish. How close is too close? (The bike is still half torn apart so I can't really test for chain rub at the moment.) As you can see from the photos, only about half of the lock nut extends outside of the cassette lock ring which is roughly 2 mm. The thickness of the cassette lock ring is about 1.4 mm so I have about 3.4 mm (give or take) from the smallest cog to the inside of the drop out. Is this enough?

Would I be better off using the old spacer (-3 mm) and adding in a washer on each side (+3 mm total), moving the cassette further back approximately where it was? (and re-dishing). This also would help get the lock nut back out for better access when adjusting the cones. However, I think having the cassette closer to the frame would make a slightly stronger wheel because it would have less dish.

I'm not sure what the normal practice is for spacing. Any advice or suggestions would be appreciated. Thanks

ps... I thought I had my bike fairly clean until I looked at the photos taken in macro mode...

CliffordK 03-06-18 04:31 AM

You should be fine with the space to the chain.

If you remove the cassette lockring, you'll have better access to the right lock nut. You can do most of your cone adjustment with the left cone and locknut, and leave the right side locked in place.

Bike tinker man 03-06-18 07:22 AM

I tend to agree the old story - a miss is as good as a mile - you have to remember often the front RD only has the same or less clearance on the chain, one also considers one pedaling how much of the time are you going to be on the highest (lowest teeth) gear. If its a problem when you assemble it, dropping the wheel out adding a washer to give more space on the rear chain stay is very easy.

gnrboyd 03-06-18 09:03 AM

I guess I will leave it as is and see what it does when I get the bike put back together. Thanks for the feedback!

Iride01 03-06-18 09:03 AM

While I agree that a miss is as good as a mile, the other consideration is chain line. It's generally considered ideal from center of the front cluster to the center of the rear cluster. Though the range of your derailleur and some other stuff can make the tolerances more foregiving.

Moving the rear cluster over might make shifting to the smallest cog more difficult or cause the chain to rub the front DR cage or even come off the front chain wheel.

But........ if it does not, then we are back to the "a miss is as good as a mile" So if you don't see issues, it's not a problem.

ThermionicScott 03-06-18 01:57 PM

Provided the chain isn't grinding on the dropout, having the cassette closer to the dropout is actually a good thing. Redishing means that you were able to put a little more tension into the NDS spokes and take a little out of the DS spokes. Some of us do this kind of thing on purpose. :thumb:

gnrboyd 03-07-18 12:36 AM

Since the bike is still half torn apart, it makes it difficult to check for chain rub and chain line. Hopefully, I will get more time this weekend to put some of it back together so I can get a final verdict. Thanks to everyone for the input.

CliffordK 03-07-18 12:46 AM


Originally Posted by gnrboyd (Post 20209231)
Since the bike is still half torn apart, it makes it difficult to check for chain rub and chain line. Hopefully, I will get more time this weekend to put some of it back together so I can get a final verdict. Thanks to everyone for the input.

Hard to tell for sure without everything being together, but from your picture, it looks like you still have about 1/16" clearance.

I'm doubting you'll get any rub. Just make sure you don't leave any fender/rack bolts too long.

SJX426 03-07-18 06:54 AM

It is one thing to make sure the chain doesn't rub on the DO, it is another to have enough clearance on the seat stay to allow the chain to move from one sprocket to another. It is more a configuration of the stay "exiting" from the DO.

Obviously, all you need is a functional drive train to test.


All times are GMT -6. The time now is 05:32 PM.


Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.