UKH

I’m pretty new to cycling, only getting back into it after an absence of 30+ years this spring due to increasing pain and stiffness in my previously injured left ankle, which was severely limiting the amount of walking and climbing I could do at the time (and still is).

I initially bought a cheap and cheerful Decathlon bike to ride around the trails near our base in Catalunya:

https://www.decathlon.es/es/p/bicicleta-de-montana-mtb-29-aluminio-rockride...

but on returning to Sheffield I decided I wanted something lighter (my XL model Decathlon weighed 15.05Kg without pedals!) and more suitable for some road and gravel use, so I bought a rigid fork Planet X ‘Whippet’. It’s a great bike which, thanks to its carbon frame, manages to break the 10.5kg barrier despite the chunky wheels and tyres. However, now back in Catalunya and having brought the ‘Whippet’ down with me, I realize it most certainly isn’t the right machine for my trail riding here, at least not with the rigid front fork. During my first short ride a couple of days ago, not only did my wrists and elbows suffer a beating, but the front end of the bike felt so jittery I could hardly keep upright on faster sections.

As we are frequent visitors to Catalunya and I’d really like to do much more trail riding here, I reckon I have two choices: a) buy a suspension fork and either try fit it myself or get a bike mechanic to do it, or b) buy another bike, more suitable for the terrain I want to ride. I should add for clarity that I no longer have the Decathlon bike I bought in the spring.

Given how much I like riding the ‘Whippet’ (on roads and gravel) in its current form, I’m leaning towards option b, but I’d welcome thoughts from more experienced riders, particularly those who have gone through the process of fitting a new fork.

Pete.

As always, an answer you didn't ask for: have you tired bigger tyres and/or lower tyre pressures?

Filling that, always n+1, so option b. Sounds to me like you have different jobs and hence need different tools. Your other option would be to get a suspension fork for the MTB you have, and use that for more technical trails, then get a gravel bike for your gravel/road stuff.

Not tinkered with mountain bikes for a few years now, but a fork swap is pretty straightforward if you have basic mechanic's skills.  You should be able to use the same headset as fitted to the Whippet - I'm guessing it's 1 1/8 to 1 1/2 inch taper.  When removing the fork crown race this will require care and can sometimes be a pita (interference fit) so I'd get a new replacement crown race and fit this to the new fork to save potential hassle.

You'll need a fork of suitable travel for the optimised travel the frame design accepts.  See what On One are fitting to the Whippet.  I've found a lockout feature which has a handlebar control very useful in the past so consider this when choosing a fork.  Out of touch but I'd guess a new fork will be ranging from £300 to £600 for reasonable to good quality.

The scariest job will be cutting down the fork steerer tube.  You'll need a sharp hacksaw blade - new is best - and cutting guide or pipe style cutter (depending aluminium or carbon steerer) to do a decent job.  Measure three times and cut once!

Park Tool's guides are good for instruction. 

The suspension fork will add weight but shouldn't be too noticeable unless you are doing a lot of hike-a-bike.  If you're enjoying the Whippet I'd be tempted to go suspension fork rather than new bike.

Can you fit larger size tyres to the Whippet? This will give you a bit more "forgiving" rear.  Also worth experimenting with tyre pressures close to home.  I used to run 28psi on the rear of a Stiffee (before tubeless) and never had problems.  You'll be able to go lower if you go tubeless too.

Hope this helps.

I actually have a nice gravel bike (Planet X Holdsworth Mystique) back in Sheffield. The plan was to leave that one there and bring the Whippet down to leave here.

Re bigger tyres: good idea. I swapped the original 2.3" tyres that came on the Whippet for 2.0", but I've brought the old tyres with me, so that could be a start. And yes, come to think of it I have got the pressure pretty high...

Cheers,

Pete.

I'm not too shabby at bike DIY but I don't have any workshop facilities here. I've looked at the video tutorials on You Tube and you're right... sawing the steerer tube correctly does look pretty scary! 

I contacted Planet X customer service and they got back to me straight away with the technical specs I need to look for if I go down the new fork road.

Cheers,

Pete.

Checked PlanetX website and the Whippet is designed to be stiff, so no surpise what you're experiencing.

It also mentions it's designed to take a 100mm travel fork, so that's a good start. As GhastlyRabbitFat says, it's a straightforward swap. In my experience, the hardest bit is getting the star nut into an alloy steerer. If it's carbon, you'll need an expanding bung (which you could also use with an alloy steerer, for less faff). Leave the steerer a bit longer than you need and pack it with spacers - you can always take more off later. If carbon, you should use a specific abrasive blade - not a toothed blade, although many people do - and don't breathe the dust.

You may be able to get away with a 120mm fork - check with PlanetX, but be aware it will adjust the geometry and might muck up the handling.

Edit - check the fork dropouts are compatible with your front hub!

Apart from cutting the steerer, which a local bike shop could do for you, you should only need a couple of hex keys to swap it.

Did it once on a mate's bike in a bunk house with no workshop facilities

I used to find getting the star nut installed quite satisfying, so long as you're using a guide.  About the only job on a bike (don't mention cotter pins) where you can really whallop something with a hammer

I'm pretty sure I could sort out somebody to do the sawing accurately. In fact, now I come to think of it, our friendly plumber here is a keen mountain biker himself, so he might be able to help.

Alex at Planet X sent me these specs:

Travel-between 100-120mm
Steerer size: 1 1/8th-1.5mm tapered.
Disc type: post mount
Offset: 46mm.

I think you guys are changing my leaning from new bike to new fork. Only problem now is wading through the masses of models available and trying decide which one...

Cheers,

Pete.

Pretty certain that's the standard for all forks these days, but you can get IS to PM adapters if you need them.

Good luck. Definitely recommend remote lock-out.

Could you post a link to the type of thing you want to be riding pls?  What we talking about here?  Blue or reds?  

Re: Swapping a fork

Difficult = no i.e. you need limited tools and basic mechanics, but you need to get quite a few things right - star nut maybe being the easiest:

1. Generally speaking .. you can go +/- 20mm without affecting the ergonomics of how the bike was designed to ride.  i.e. if you determine that you need >20mm more than what you've got on the bike right now .. then you probably need a new bike - not a new fork.
2. Steerer tube.  Nearly all are tapered ... some very old/cheap ones are straight.  Buy the right one.
3. Wheel size.  A fork that can run 29's will take 27.5 .. but obviously not the other way around.  If you want to move up to 29s ... now is the time to make that move.
4. Offset.  Your existing fork will have an offset .. maybe 30-40mm ... you want to match that with your new fork like-for-like.
5. Axel.  Unless you want to change your front hubs ... you need to match axels between current and new forks.  i.e. if you're running 110m thru axels .. then you probably want to stay the same.
6. break mounts.  On most MTB's ... you're running break mounts direct onto the lower tube.  Unless you want to replace your rotors/breaks ... then you need to make sure they'll fit your new fork.

So .. a few things you need to get right if you don't want to change our other parts in parallel.

I'm not a fan of trying to make a bike do what it was never designed to do in the first place.  In my experience you end up with a bit of a Frankenstein and it still doesn't ride that well.  

If you want to ride trails .. buy a trail bike.  I'd guess, based on your description above, this would more than suit your needs - https://www.wiggle.com/vitus-sentier-29-mountain-bike ... hard not to see the value proposition with the Vitus bikes for intermittent/not hardcore riders.

Oh ... and here is instructions to fit a new fork ... I think it is like-for-like what I said.

https://www.worldwidecyclery.com/blogs/worldwide-cyclery-blog/the-basics-of...

If you buy a 2nd hand fork .. make sure there is enough steerer tube left!!!!!!!!!!!!!!!!!!!

Thanks Stu, I will sit through that with my evening beer.

In the meantime, I have refitted my 2.35" tyres (learning how to remove rim-stuck tryes with a wooden block in the process) and set the pressure at 40PSI. Let's see if that makes a difference...

Pete.

The whippet will take a 100 to 120mm fork no problem (Planet x sell a 100mm travel version).

If you get a fork from a local bike shop, they will normally fit for free; or charge minimal cost.

The front hub will also need to be either compatible or changeable to fit the desired fork; but a new front wheels wont be 'that' much .....  There is a whole quagmire of axle and hub widths 'standards' to grapple with (there is no single standard, lol).

The key question is how much do you want to spend on a fork ...

Tyres, tyre width/volume and tyre pressure  (plus tubes versus tubeless, liners etc) are whole other areas to think about and can make or break ride quality. 

It's "brake", FHS...

There are a myriad of adaptors available - there will be a solution to get the existing brake calliper attached to the fork with the required disk size (deciding on which adaptor is needed is the hard bit and where a LBS can help).

Yeah. I renovated a 90s saracen frame and fitted new remote lock forks. I just bought a mount of the right depth so the brakes sat correctly. 

Op. https://www.tredz.co.uk/bike-brake-mounts

Thanks for the all the additional advice folks. Lots to think about...

Quick update: I've just been for a 20km spin with the refitted 2.35" tyres, starting on some better maintained farm trails than I rode on Monday, but eventually joining up with exactly the same ground, and all I can say is I'm blown away by the difference.

On the initial smoother trails, the Whippet seemed like it was made for the job and the riding was superb. Once back on the rough stuff, it wasn't quite as much fun, but nothing like the out-of-control riding I experienced on Monday. I also found that by gripping the bars more lightly, less vibration was transmitted to my wrists and elbows.

All of which means I can now take a bit more time considering my options. A suspension fork will definitely be necessary if I want to go any rougher, but in the meantime I can still have fun with my Whippet providing I stick to the right ground.

Pete.

The whippet will always be a xc bike but certainly a more capable bike with a sus fork than rigid. 

Fitting forks isn't a hard job, not even cutting the steerer tube unless it's carbon and then you need a special blade etc. You can use tape or card wrapped around the steerer tube as a cutting guide and assuming you are keeping the headset and stem you can measure the old fork for length. I often add a few mm to give wiggle room and space for a spacer on top of the stem clamp.

Also, 40 psi on a 2.3 inch tyre is probably too much, especially if you run tubeless. And adding suspension allows even lower pressures.

For the rougher stuff, bring down the front tyre pressure in 5 psi increments to find you sweet spot of comfort versus snake-bit risk (if running tubes) combined with your weight and riding speed; you might get away with down to 25psi on front with an xc tyre, but that will not give much margin of error in chunkier stuff for snake bites.

Rear - probably 30 ish.

You'll also find cornering a bit nicer off-road (ie more grip) than when you were at >>40 psi  ... that will get sketchy quickly !

There is always a downside with lower pressures, they'll be more drag on smoother trails and tarmac; but you'll soon find the best overall compromise for the trails you end up riding.

On a rigid (all MTBs really, but especially rigid), bar grip choice and the bars can also make a big difference to comfort.

I'm not currently running tubeless and the minimum recommended pressure for these tyres when using inner tubes is 35 psi, but I suppose even 5 psi could make a difference.

Cheers,

Pete.

40 psi is hard in the MTB world.  I run 24 psi rear, 23 front.

Yeeek ... sorry all ... that would have annoyed me too!

Thanks for the additional ideas on tyre pressures. As I've just said to Gethin, I'm not currently running tubeless and these tyres have a minimal recommended psi of 35.

I might experiment with slightly lower pressures on rides over the next days, but I'll be sure to have a spare tube to hand for snake bite...

Cheers,

Pete.

Blimey. I think the major upshot of this thread is that I might not really need suspension forks at all, let alone a new bike, for the kind of riding I do here, I just need to let some air out of my tyres!

Cheers,

Pete.

That's a really interesting fork on that bike now I've gone back and looked at it properly.    Got a kind of XC race vibe to the bike with that fork on.  Well spec'd!  SRAM GX eagle not common a bike at that price point and a big step up on the NX model below it.

This is it right - https://www.planetx.co.uk/i/q/YBOOWHGX/on-one-whippet-sram-gx-carbon-fork-m... ???

I'm going to guess that it's exactly the same ALU frame on your bike as the suspension model .. which comes with 100mm of travel.  

Assuming we're correct .. then you should be able to go up to 120mm without messing with how the bike rides.  The question then is ... is 120mm enough?

I don't get the feeling you're doing any drops or jumps (pls tell me if I've got that wrong).  120mm is plenty for general trail riding on a hard tail. 120mm of travel will make a big difference to how hard your arms/hands have to work.  

Next question - how much should you spend on front forks? Others may disagree with me .. but IMO you can't get a descent trail fork for <£400.  Obviously .. depends how hard you ride.  If you're dropping off things then I definitely wouldn't bother buying a <£400 front fork ... you'll just eventually trash it and the cost of servicing a fork makes it uneconomical to service at that price point.  In many cases, if you've got a wrecked <£400 trail bike fork that's, say, 2+ years old  ... most good bike shops would advise you simply to replace the whole fork.  They will service it for you if that's what you want .. but they will not give any guarantees that you're not back in front of them pretty quickly with it again.  Not the case on the more expensive forks.  The expensive forks it certainly is worth servicing.  

My suggetion:  A lovely 120mm Fox 34 would be a good investment.  

If willing to buy 2nd hand .. pinkbike is a good option:  https://www.pinkbike.com/buysell/list/?region=5&category=9&wheelsiz...  ... I've had good experiences here in the past.  If buying a fox fork .. have them give you the 4 digit code off the back of the fork and look it up on the fox website to check spec and age.  

If it were me .. I'd choose an excellent condition, higher end, 2nd hand fox 34 fork ... over a brand new fork albeit lower spec.  

(Don't bother with their grip2 damper if you get a choice.  I have it .. does my head in.  97% of riders .. don't need this much customization)

Tell us here what you finally settle upon.

Cheers.

Yep, that’s my Whippet, although I bought the black version as opposed to the orange model. 

Not doing any “drops or jumps” if I can help it!

I will, and thanks again for your help.

Pete

You could also up the volume of the front tyre for more comfort.

For example, Vittoria do their Barzo XC 29er tyre in a 2.6 inch variant.

(Currently have one on the front of my hardtail which is in 'XC mode' as part of injury rehab for getting the miles in - its pretty good and still surprisingly fast rolling even at at 2.6).

... other larger volume XC tyres are available ...

Just a quick update…

After a few more trail rides on the rigid fork Whippet I decided that I would definitely enjoy the experience more with a suspension fork.

As I didn’t really need anything super technical, I went for a RockShox Judy Gold with 100mm of travel, which set me back around €290 online. I have basic tools here, but I needed to purchase a pipe cutter (don't have access to a vice so hacksawing didn’t seem wise) and a star nut insertion tool, which added €20 to the overall cost.

After watching quite a few videos on You Tube, I finally felt confident enough to do the job this morning.

As others have said, providing you're really careful about cutting the top tube to the correct length, it's not difficult job…a makeshift bike stand utilising a sturdy washing line frame and various slings and bits of old climbing rope really helped!

Just got back from a short ride and I'm really pleased with how the new fork performed…back to being able to go 'full tilt' on the faster sections. The one downside is the additional weight… probably around 1.7kg heavier with the suspension fork, but I always knew that would be the case.

So, once again, thanks for all the sound advice. You may well have saved me splurging out on a new bike for little or no gain!

Pete.

Out of interest, how noticeable is the extra weight when riding? I've wondered a few times whether to go rigid or suspension fork, so it would be good to hear from someone who's tried both options on one bike.

his rigid bike was 10.5 kg to start with, so will still be sub 27 lb (in old money), so still respectable.

... a sub-10kg (22 lb) hardtail will set you back a mighty chunk of cash.

The rigid 'Selcof' carbon fork, when I removed it, felt almost weightless and I've already said how much I like riding the Whippet in this configuration, providing the trails are suitable. The new RockShox fork is in the 2kg range… so yes, a considerable gain in weight… maybe an extra 1.7kg

I can definitely feel the difference when carrying the bike up the few steps to our storage room, but not so much out on the trails…in fact, the extra weight at the front end seems to have added stability on the loose surfaces.

As Chris JD says, a nice handling hardtail 29” mtb around 12kg is not too shabby, and it would cost a good chunk of cash to make further worthwhile weight savings.