[Closed] I'm feeling OFFSET Saturday night fever

No one!?

There was me thinking stw had at least one answer for every question on here ;-d

I don't know the answer but this article I found interesting

https://www.bikeradar.com/mtb/gear/article/pushing-the-limits-of-fork-offset-an-experiment-45343/

Back in the early days of 29ers, there were debates about what geometry worked.  Those were the days of shorter steeper 26ers anyway.  By definition, offset doesn't affect head angle, but a combination of offset and head angle affects trail (which is the distance the contact patch lies behind an extension of the steering axis to the ground).  If you do the trigognometry, with bigger wheels you get more trail for the same HA and offset.  So, peeps argued, something must give to achieve the same trail as on a 26er.  (Not so may people challenged the assumption that you needed the same trail, you can argue that the bigger diameter and shallower contact angle of the tyre means you need more trail, but anyway...)

So initially peeps upped the HA on 29ers from steep to steeper.  Apart from on small frames, where the Toe Overlap Issue came to the fore.  But then they got in cahoots with fork manufacturers or made their own (rigid) forks so increased the offset instead.

Now we live in a world of slack is good.  There are a range of views on whether big trail numbers are good or not, some manufacturers (Transition and I think Gemoetron) argue for small offsets as well as slack angles, others reckon bigger offsets should go with the slacker HA.

So I would not assume there is any correct figure.  With short offset and high trail, particularly if your bike has a slack HA already (which will get slacker with the longer fork), you may feel the phenomenon known as "flop" and not like it, but your bike will be stable at speed.

Personally I wouldn't worry about it that much.  My FS bike has a lot of flop since I fitted an angleset, but I have got used to it.  My HT has a 68 degree head angle and 46mm offset and feels fine also.

The offset won't really change your position on the bike.

The longer fork will reduce the reach & increase front end height so will change your position on the bike slightly (less perched forward).

The shorter offset will "raise" the fork in relation to the front hub, so it will slightly change every relevant measurement.

Another new article on this topic:  https://nsmb.com/articles/short-fork-offset-whats-it-good/

+1 excellent answer from Greyspoke.

I don't think you'll notice. My FS has 46mm offset; HT has 51mm offset, I really can't tell any difference. Thye're both about the same HA.

Thanks guys for the detailed swift response.

I have a fairly steep HT that I am slackening out with 20mm more travel and the 51mm offset which should work wonders for that 70 degree it was before. In conjunction with what I will be using as a short 35mm stem instead of the 65mm one before, I should achieve what I want and have an eggcellerent ride.

That and the fact I'm adding a dropper to make this bike more user friendly on the downs and ups of course which will bring out the inner hooligan even if it does have qrx135mm rear end - it's alllllll goooood!

😀

If you want it slacker *and* lower a la mode, you could always stick a 27.5 wheel in the back.  It would look cool even if it rode oddly.

Thanks for the suggestion but no thanks, ;D

I got a 650b + fully for that kinda thang

The longer fork will slow down steering by slackening HA (and reduce reach, raise BB and slacken SA), while increasing the offset will speed up the steering, so they’ll cancel one another out to some extent.

Nsmb.com have an article on this subject today.

“I have a fairly steep HT that I am slackening out with 20mm more travel and the 51mm offset“

Increasing the offset does put the front wheel further in front of you but counterintuitively it actually shortens the trail figure thus quickening the steering.