Couple of fork-related questions

tawfeeredux

I already have a non-integrated headset, but a lot of the forks i'm looking at say they're designed for integrated headsets. Are these forks therefore incompatible with my headset & do I need to find a fork that's designed for non-integrated headsets?

The fork on my current bike has a 43mm rake. Some of the options i'm looking at (i.e. the ones I think will look the prettiest on my new bike build) have 45mm rake. Is there any noticeable difference on the road between a fork with 43mm rake & one with 45mm rake?

DualFrontDiscs

I'd be interested in hearing an answer to this question also. I'm considering swapping my current fork with 50mm rake for one with 45mm rake. It's a touring frame. Discuss......

DFD.

Gavin

Don't know about the rake but you have to get the same headset alright. It's the frame that limits the choice

DualFrontDiscs

Gavin wrote: »

Don't know about the rake but you have to get the same headset alright. It's the frame that limits the choice

Fair point, existing and potential replacement are 1 1/8"

Any thoughts as to the impact of a reduction of 5mm in rack? From 50mm to 45mm?

Thanks,

DFD.

tawfeeredux

DualFrontDiscs wrote: »

Fair point, existing and potential replacement are 1 1/8"

Any thoughts as to the impact of a reduction of 5mm in rack? From 50mm to 45mm?

Thanks,

DFD.

I've been doing a bit of research since. You're possibly already aware, but reducing the rake is supposed to make the steering slower and handling more stable. I've read a good few opinions that a reduction of 2-3mm in rake would have a negligible impact on the bike's handling, not sure about 5mm though.

Another factor to take into account is the length of the fork (though I had assumed they were all the same length). A longer fork will increase stability also.

papac

DualFrontDiscs wrote: »

Fair point, existing and potential replacement are 1 1/8"

Any thoughts as to the impact of a reduction of 5mm in rack? From 50mm to 45mm?

Thanks,

DFD.

Assuming nothing else (wheel diameter/head angle ) remains the same then I would think that decreasing fork rake will increase the trail thus making the bike steering more stable and slower. Whether this is an issue or not depends on personal preferences and what you are doing with the bike.

One does have to be a little bit wary I suppose. Bikes are designed and tested with a given fork offset and changing that could open up the possibility of handling gremlins-(shimmies are interesting if you're into experimental physics but to be avoided otherwise.)

As a kid growing up in a bike shop we used to do all sorts of jiggery pokery with fork and wheel sizes-we must have had some ridiculous trail figures but I'm still here. (Albeit with a few broken bones:D)

http://www.dclxvi.org/chunk/tech/trail/

DemystifiedForkDesign??

Edit.Forgot it's a tourer. If its a well designed tourer it probably has a shallow head angle and a long wheelbase. My instincts tell me it that the change in fork offset- while it will slow the steering-should be less noticable than on a twitchy road bike. I am tired now so I may have to review that opinion in the cold light of day.
If you can post geometry figures for the bike we could work out before and after trail figures for the craic. We would need tyre size as well.

DualFrontDiscs

@papac

The geometry of the tourer looks like:

The proposed fork is a Surly LHT fork

Any and all advice appreciated.

Regards,

DFD.

papac

Assuming same tyres and comparing the geometry with the LHT
http://www.surlybikes.com/frames/long_haul_trucker_frame/

by fitting lht fork to the Litespeed you will have slightly more trail than the Litespeed currently has obviously.

Using formula here http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_geometry

Trail figures.
Small Litespeed own fork-61mm
Small Litespeed LHT fork 66mm

Large Litespeed own fork 54mm
Large Litespeed LHT fork 60mm

All 700c Surlys LHT fork 63mm

I have assumed 340mm wheel radius- Ballpark 700-28.

Also assumed negligable difference in fork length. If there is a difference it will change the head angle slightly for the Litespeed calculation.

For our purposes there are only 2 sizes of Litespeed. 71.5 head angle and 72.5 head angle.

Only one size of Surly for same reason.

Imo the trail differences will be less noticable on the larger sizes with longer wheelbase however.

From all the figures to hand it looks like the Litespeed with Surly fork would have similar handling to the LHT.(Wheelbases are similar.)If it were mine I'd go for it.
I have done this in a hurry at tea break so E&OE and Caveat Emptor of course.