Will a 10mm longer fork make my bottom bracket drop lower at full travel

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Will a 10mm longer fork make my bottom bracket drop lower at full travel
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Posted: Nov 17, 2019 at 21:38 Quote
I have a 2018 transition sentinel with a fox 36, will making my fork go from a 160 to a 170mm fork my my bottom bracket drop lower?

Thanks

Posted: Nov 18, 2019 at 5:55 Quote
Your increasing the fork travel by 10mm, thereby adding 10mm to the
height, what makes you think the bottom bracket is going to go down
as a consequence ?

Posted: Nov 18, 2019 at 7:57 Quote
But wouldn’t making your fork longer allow the uppers to go deeper into the lowers? I know that at sag or in the stand it would be higher, but at full travel wouldn’t the bike have more room to drop farther down?

Posted: Nov 18, 2019 at 10:31 Quote
No, think about it. The front is higher, think of it as a triangle. The BB is on one of the lines which goes from the hub (front wheel) to slightly behind the BB and in front of the seat tube. The headset is one of the corners. Corner one as said previously between hub and seat tube, two headset, corner three front-wheel hub. The change is in the headset height. and where the BB on the line to the headset. Increase that headset corners height will also increase the height of the bottom bracket.

Posted: Nov 18, 2019 at 10:42 Quote
To make it simple when you increase the travel in your fork, your fork gets longer. It doesn’t travel further into the lowers. If your fork is designed to be increased it means part of the stanchions are locked into the lowers. Increasing the travel unlocks that hidden lower part of the stanchion and makes the whole fork longer

Posted: Nov 18, 2019 at 10:42 Quote
Putting the longer fork will raise it while uncompressed. While fully compressed it should be at the same level

Posted: Nov 18, 2019 at 12:28 Quote
It depends on the axle to crown lenght. If it stays the same, yes you will get a lower bike at bottom out. The difference will be little though. If the axle to crown lenght is longer, then the height of the bike will be about the same.

Posted: Nov 18, 2019 at 16:31 Quote
ORTOGONAL555 wrote:
It depends on the axle to crown lenght. If it stays the same, yes you will get a lower bike at bottom out. The difference will be little though. If the axle to crown lenght is longer, then the height of the bike will be about the same.

No.

Posted: Nov 18, 2019 at 17:09 Quote
Branmuffin wrote:
ORTOGONAL555 wrote:
It depends on the axle to crown lenght. If it stays the same, yes you will get a lower bike at bottom out. The difference will be little though. If the axle to crown lenght is longer, then the height of the bike will be about the same.

No.

Actually, they're right. Keeping the same ATC with 10mm longer travel means it will compress further. If the ATC is longer than the original ATC (about 10mm longer) it will be the same when compressed. If OP is using the same fork with a longer air shaft, the ATC will be 10mm longer, but fully compressed will be the same

Posted: Nov 18, 2019 at 18:24 Quote
matt-15 wrote:
Branmuffin wrote:
ORTOGONAL555 wrote:
It depends on the axle to crown lenght. If it stays the same, yes you will get a lower bike at bottom out. The difference will be little though. If the axle to crown lenght is longer, then the height of the bike will be about the same.

No.

Actually, they're right. Keeping the same ATC with 10mm longer travel means it will compress further. If the ATC is longer than the original ATC (about 10mm longer) it will be the same when compressed. If OP is using the same fork with a longer air shaft, the ATC will be 10mm longer, but fully compressed will be the same

I suppose it does depend on fork manufacturer. Coming from a DVO Diamond with adjustable travel, you only go up. Fox seems to work the opposite way, when changing the travel.

With a 10mm change at the fork, what kind of bb drop would we see? 2-3mm?

Posted: Nov 19, 2019 at 0:35 Quote
I think the relative drop of BB height is dependent on the wheel base and the head angle. However I wouldn't texpect more than a few mm drop, if even noticeable.

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