Changing forks. 29" sus 63mm travel to 100mm UPDATE RESULT

[Brucey]

....Still only 21mm height increase.
Run the fork with 12-15mm sag, that's back at 10mm difference, half a degree on the head angle.

er, last time I checked, 100-63 = 37
so the head angle/trail will be substantially changed. I would opt for 51 mm offset all day long.

[rareposter]

....Still only 21mm height increase.
Run the fork with 12-15mm sag, that's back at 10mm difference, half a degree on the head angle.

er, last time I checked, 100-63 = 37
so the head angle/trail will be substantially changed. I would opt for 51 mm offset all day long.

It's not about the travel, it's about the axle to crown length.
RS: 509
Suntour (current forks): 488

21mm difference.
Knock off half of that due to running some sag in the forks.

10mm difference, half a degree head angle. And even that is offset when the forks compress.

[Brucey]

OK but the extant trail is already OTT IMV, plus you appear to be assuming that the present forks are being run with no sag whatsoever.

[deliquium]

OK but the extant trail is already OTT IMV, plus you appear to be assuming that the present forks are being run with no sag whatsoever.

I haven't got around to measuring how much the current cheapo (seemingly pointless?) Suntour NVX30 forks sag/move whilst riding. They obviously compress when the front brake is applied sharply. They are adjusted to their softest limit. But on tarmac and gravel, I can't feel nor see any movement in the forks. With age and shoulder issues, my riding position is more upright than it ever was in the previous 65 years cycling - although the bars are only just above saddle height.

If it's dry tomorrow I'll go for a ride - firstly tarmac and then to the forest hardpack 'gravel' - and try to measure - assuming I won't have to use the brakes to muck up the actual riding fork travel.

I suspect (but could easily be wrong - that's always a given) there's around 0 geometry change when not braking or hitting potholes, with these for show only and fashion? Suntour NVX30 forks?

Have noted what Jezrant and 531colin have rightly mentioned - "it's the tyres stupid" (to misappropriate a quote from somewhere else?) forks are not the key to my kinda riding comfort. But other than having some custom made rigid forks, I can't find anything that appear to be suitable (apart from possibly some alu 'Exotic' brand onesfrom https://www.carboncycles.cc/?s=0&t=0&rb=6&.

So if the 100mm travel 42mm offset RS Judy Silver will work (and help a little in case a pot hole or wee unexpected drop present themsleves), then that'll be around the same price-ish.

It's not as if weight is of any concern on a 25kg Cube panzer style e-Bike with a 625W battery Which I nevertheless enjoy riding immensely

ps IMPORTANT the current NVX forks and bike's geometry - provides more than satisfactory handling for this fella, whatever the trail 'number' currently is That is, it steers and leans how I like at slow speed and my slow 'fast' too. And even though riding 'no hands' is a silly and dangerous thing - it does it with ease - (unlike 531colin I have never had the cajones to try and slalom no hands in and out of cat's eyes on any bike ever)

[Cowsham]

@ Cowsham: Kona?
https://www.konaworld.com/en-uk/product ... atte-black
I was also thinking of an Orange fork like that but not sure of the a2c. A 'wanted' ad might turn up others.

auto-.correct keeps changing your username into cowshed!

Thanks very much Jez I've sent a request for info.

I hope the cowshed has the non exploding cows in.

[deliquium]

Finally got around to measuring the amount of actual travel on the SR Suntour NVX 63mm forks road riding and without any serious front brake use - surprised me at ~28mm. Wasn't actually aware they moved that much.

Any road up, I eventually bought a pair of Rockshox Judy TK Silver 100mm with 51mm offset, not the 42mm originally considered. £149.99 new from Winstanleys.

One day I'll get around to fitting them and hoping all will be fine.

Thanks everyone for advice and info - all very useful to this large wheel suspension bike newbie

[deliquium]

Apologies for seeking information again about steering geometry and bicycles - I still can't make myself understand

I have a Cube Reaction Touring One e-bike with 29" wheels and 55mm tyres. Head angle 69.5º. Cheap Suntour forks with [EDIT to correct to 63mm travel and 42mm offset.

So here's hopefully a couple of simple questions?

1. What would happen if the Suntour forks were replaced with slightly less cheap Rockshox Judy Silver forks with 100mm travel and 51mm offset?

2. What would happen if the Suntour forks were replaced with slightly less cheap Rockshox Judy Silver forks with 100mm travel and only 42mm offset?

This e-bike is not used for racing, thrills or technical off road. It is used gently on and off road - the latter being hard pack forest trails.

(The bike is a Cube and note their entry level e-MTB has 60mm tyres. Head angle 68.5º. 100mm fork travel with 42mm offset. Cube's next 'level' e-MTB has 65mm tyres. Head angle 67.5º. 120mm fork travel with 42mm offset)

Finally got around to doing this. Just back from first test ride = ACE

Fitted 100mm Rockshox Judy Silver with 51mm offset* - to replace the stock very (very) basic Suntour 63mm with 42mm offset forks.

Steering characteristics are just great - this rider is not aware of any difference in that respect. This is with regard to road and hard pack gravel fire roads surfaces - I am not intending to use the bike on anything remotely 'technical' whether that be rocky, downhill, tree rooty. or muddy - and certainly not fast.

What is different is the quality of the suspension and ride and how easily adjustable it is. I am so very pleased

* https://winstanleysbikes.co.uk/rockshox ... -2021-fork

Thank you all for advice and technical info earlier, very much appreciated

[Cowsham]

Great to know we've been of some help and you've had good success. I've had success too with my conversion to rigid suspension corrected forks -- very pleased with the result. ( Cube make great bikes too )

If you'd not bought your forks first you could've had my 100mm silver air rock shocks with remote lockout -- I think they would do 29er too -- I seem to remember the cube acid came as a 29er and the same forks came on both the 27.5 and 29 the only difference was the size of the wheels.

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