Fork lug axle offset question

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2/26/2018 8:15 AM

Picked up some Showa Twin Chamber forks from a 2008 CRF450 to put on my 1996 CR250, and I believe the offset of the axle on the new forks is -2mm compared to the KYBs that came on the 96. I assume this would make a difference in handling. To correct the issue, would I just need to slide the forks a little further down the clamps? Ideally I'm trying to get it back to the stock wheelbase spec - correct? Thanks in advance!

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Positively, absolutely 110% obsessed with anything MOTO.

2/26/2018 10:50 AM

F150Motocrosser wrote:

Picked up some Showa Twin Chamber forks from a 2008 CRF450 to put on my 1996 CR250, and I believe the offset of the axle on the new forks is -2mm compared to the KYBs that came on the 96. I assume this would make a difference in handling. To correct the issue, would I just need to slide the forks a little further down the clamps? Ideally I'm trying to get it back to the stock wheelbase spec - correct? Thanks in advance!

If you could get clamps that are +2mm that would be best. Not sure if fork height would do the same thing?

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2/26/2018 11:18 PM

For the most part, fork length has been pretty normal across Hondas from 95 up, give or take a few mm, save for the 500. If your axle offset is different, raising or lowering the forks in clamps isnt going to do anything,
But, ive done what you are thinking of doing, and it handled great. I used the stock 24mm offset triple clamps as well.
I remember measuring all that stuff and never found a difference. But if you are 2mm off, you can change triple clamp offset to compensate.

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2/27/2018 1:41 PM

Byron909 wrote:

For the most part, fork length has been pretty normal across Hondas from 95 up, give or take a few mm, save for the 500. If your axle offset is different, raising or lowering the forks in clamps isnt going to do anything,
But, ive done what you are thinking of doing, and it handled great. I used the stock 24mm offset triple clamps as well.
I remember measuring all that stuff and never found a difference. But if you are 2mm off, you can change triple clamp offset to compensate.

Thanks for the input man. When you say you've done what I'm thinking of doing, do you mean the Showa TC swap on a steelie CR250, or just lowering the forks in clamps to achieve better handling characteristics?

But yea, in 2005, Honda moved the axle back -2mm in the forks. So something tells me the forks you used were pre-05, correct?

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Positively, absolutely 110% obsessed with anything MOTO.

2/27/2018 2:02 PM
Edited Date/Time: 2/27/2018 2:05 PM

Yeah, 95 cr250, 2003 cr250 forks.

Maybe you should use some pre 05 lugs ? So if you use the 05 up, and its 2mm farther back, itd be like having a 22mm offset clamp. Ive done that on cr250s. To twitchy for me.

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3/1/2018 3:58 AM

Have you ridden the bike / the same model with the -2mm offset? If you haven't you might find you like the less offset / more trail it gives.

One of the best things from my putting WP CCs on my CR500 was the reduction of triple clamp offset from 24mm to 20mm ( with the further option of going to 18mm, which I'm yet to try). The lower lug offset was the same between the original Kayabas and the WPs I fitted.

The difference in front end feel is so much towards the favour of the 20mm offset - it's fantastic. A Revelation. Steering precision, stability, all far, far better than the original 24mm clamp offset.

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3/1/2018 6:32 AM
Edited Date/Time: 3/1/2018 6:44 AM

A friend of mine had a 96 model & I had a 93. There was a difference in the steering / cornering between the 2 models. Honda changed the head tube angle on the frame geometry each yr. with the steely chassis from 93-96. They changed the head angle after 93 to make the chassis more stable at higher speeds, but it was a trade of with the sharp steering the 93 frame had. I think it would be a benefit to use the -2mm Showas on the 96 frame / chassis.
I've fitted 07 CR250r Showas on a 03 CR2 with the -2mm fork lugs pulled back & felt a slight difference in cornering.

I would consider it to be an upgrade to the newer Showas. The KYB units from that era were decent, but the newer Showas with a a good revalve will give the bike a plusher ride.

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Speak softly and carry a big stick.

3/1/2018 7:20 AM

H4L wrote:

A friend of mine had a 96 model & I had a 93. There was a difference in the steering / cornering between the 2 models. Honda changed the head tube angle on the frame geometry each yr. with the steely chassis from 93-96. They changed the head angle after 93 to make the chassis more stable at higher speeds, but it was a trade of with the sharp steering the 93 frame had. I think it would be a benefit to use the -2mm Showas on the 96 frame / chassis.
I've fitted 07 CR250r Showas on a 03 CR2 with the -2mm fork lugs pulled back & felt a slight difference in cornering.

I would consider it to be an upgrade to the newer Showas. The KYB units from that era were decent, but the newer Showas with a a good revalve will give the bike a plusher ride.

Maybe one of the differences you felt was a 93 has about a 3/4” shorter head tube, if fitted with twin chambers, and that not compensated, that bike probably could go straight good, but maybe not turn so great, regardless of offset.
At any rate, nice to have options.

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3/3/2018 12:26 PM
Edited Date/Time: 3/3/2018 12:26 PM

Byron909 wrote:

Maybe one of the differences you felt was a 93 has about a 3/4” shorter head tube, if fitted with twin chambers, and that not compensated, that bike probably could go straight good, but maybe not turn so great, regardless of offset.
At any rate, nice to have options.

Byron - Found this info on pulp mx. My buddy was the faster rider of the 2 when we both raced in the 80's into the late 90's. We both felt that the 93 frame / chassis had sharper steering in comparison to the 96 model.

http://pulpmx.com/2014/08/28/gps-classic-steel-90-1996-cr250r/



While there had been better turning CR250’s (most notably, 1993), the 1996 was no slouch in the twisties. It was still plenty sharp in the corners and did a good job of walking the tightrope between twitchy and terrifying.

While the ’92 model suffered some growing pains (lack of low-end, chassis flex and frame breakage), the CR continued to be the mount of choice for pros and hard-charging intermediates. For ’93, Honda beefed up the frame and pumped up the horsepower, resulting in one of the best CR250R’s ever built. It still had crummy suspension, but oh could it handle. Nothing could turn under the scalpel-like CR as it roosted away to a sixth straight Supercross title. The ’94 and ’95 season would see minor modifications to the basic ’92 platform. A change in geometry would attempt to tame the bike’s nasty headshake (at the cost of some of that legendary turning) and a switch to Kayaba components would try to alleviate its grim suspension reputation. Even with these mods, however, the basic Honda CR250R formula persisted – a harsh ride, combined with razor sharp steering and a rocket motor. With the ’96 season approaching and a radically redesigned CR250R on the horizon , Honda prepared to enjoy one last go around with the Grand Dame of Supercross.

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Speak softly and carry a big stick.