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Online Ali-bear

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Mk2 fork springs replaced with Hyperpro kit
« on: 19 March, 2017, 05:05:14 PM »
I had my local bike mechanics overhaul my front forks and fit replacement springs from Hyperpro. Very pleased with the result.

IMHO there is nothing wrong with the Showa suspension fitted as standard to the MK2 biffer, damping is good, only it's let down (literally!) by spring rates that are just too soft. For my pie-injesting frame anyway. Before I had this work done the front static sag was well over a third of the travel, even with the pre-load adjusters turned fully in, and it very easily used up all of the travel under hard braking. It just felt too soft.

The old springs:



The Hyperpro fork springs come with a bottle of 10W fork oil and a book of instructions on how to fit. Having measured the new ones and the old ones I can confirm the new springs are shorter when uncompressed. New springs are 316mm, old springs were 331mm and the Honda service book says the service limit is 326mm.

Hyperpro instructions:



The Honda service book says the oil level should be 180mm below the top of the tubes but Hyperpro say 140mm. I believe my bike shop followed the new instructions and this has made a big difference in how the fork reacts to being compressed. It is a much more progressive feel and it is very difficult to compress to use up the travel. Static sag with three rings on the pre-load adjuster is at 26mm which is exactly what the instructions say it should be. Only they did not drop the forks 10mm through the yokes as it says there.

I was only able to get 70mm of fork travel just pumping it against the brake in the garage. The spec says 120mm total travel so I'll have to check this again after some proper riding.

Zip-tie based measurement of static sag:



I also had new tyres fitted at the same time, and while some of my initial positive reaction is attributable to those and just having the work done,  the bike feels a lot firmer at the front, not diving nearly as much while giving a very plush ride over bumps and confident cornering. So overall very pleased with the result! Recomended  :152:

I have the rear pre-load dialled up nearly to the max so the next step for me is to get the rear spring changed also.
« Last Edit: 19 March, 2017, 05:09:51 PM by Ali-bear »
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Online Ali-bear

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Re: Mk2 fork springs replaced with Hyperpro kit
« Reply #1 on: 03 July, 2017, 10:46:17 AM »
After several thousand miles still pleased. Only thing I may change is the fork oil for the thicker 15W because it does seem a bit underdamped at the front.
Designed in Japan, assembled in Italy, fiddled with in Britain

Offline nivek24

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Re: Mk2 fork springs replaced with Hyperpro kit
« Reply #2 on: 18 July, 2017, 01:04:03 PM »
hello, did you drop the forks by 10mm ?

kev

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Re: Mk2 fork springs replaced with Hyperpro kit
« Reply #3 on: 18 July, 2017, 02:02:06 PM »
No I did not. Not sure why they recommend that, the only reason I can think of is to keep the steering geometry the same as the unmodified bike?  :084:
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Offline Paul-D

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Re: Mk2 fork springs replaced with Hyperpro kit
« Reply #4 on: 18 April, 2020, 12:06:34 PM »
Changing fork springs won't change steering geometry.  The only benefit of dropping forks 10mm is that it will change the steering geometry and speed up turn in.  But stability will be slightly less when cruising in a straight line.