New forks - advice please

pulck

I commute in London on a cheap, old hybrid (GT Nomad) I bought 6 or 7 years ago for about £300.

I know there's not much I can do to improve this bike, but for ages I've wanted to try replacing the rather shabby (and probably heavy) suspension forks with rigid ones. I've never done this before, so what exactly should I be looking for to make sure I buy forks that fit?

This is what I have currently: Suntour NRX-6000 (http://www.srsuntour-cycling.com/index.php?screen=sh.detail&tnid=525&sid=1)

And if anyone has suggestions, that would be great. I'm looking for something cheap and cheerful - around £50? - as the frame is old and heavy and wouldn't warrant anything expensive.

Blue Meanie

Get forks that fit your wheel, 26" or 700c with Canti-Bosses, and your frame 1" or 1.125", and your headset threaded or unthreaded.
If it's ahead (unthreaded) you'll need a new star-nut.
Measure your old steerer and cut new forks to same length.
Remove the crown race from the old pair and transfer to new pair.

Even a old pair of steel, rigid forks will be lighter than the old sus ones and not bob up and down when you don't want them to.

pulck

Thanks for your reply. Sorry, but I have a few follow-up questions.

How can I tell if my frame is 1" or 1.125"? Where do I take this measurement?

Cutting forks sounds a bit daunting and I probably don't have the tools for the job. Presumably I can just buy them the right length? Do I need to make any adjustments to my measurements because I currently have suspension forks?

If forks are advertised as having canti-bosses, does that mean that I will be able to fit my existing V brakes?

supersonic

Measure the diameter of the fork steerer. Does it have threads? What size wheel?

pulck

Thanks for response. Wheel size is 700C.

Presumably determining diameter of the steerer and whether it is threaded or threadless is something I can only discover by taking the forks off? Will give it a go this weekend.

The Rookie

No need to take it off at all....

Threaded versus threadless, does your bike have a large nut round the steerer just above the headset, if so it is threaded, if not and the stem clamps round the steerer it is threadless.

If it is threaded you need to measure the outside diameter of the steerer just above said nut, if its threadless (probably 1 1/8) then remove the top cap and measure the inside diameter of the STEM (thus the outside diameter of the steerer it is wrapped around) then refit the top cap.

Simon

flateric

Cant add much other than this. If you need to cut your fork length down, the steerer bit, FFS DO NOT HACKSAW IT!!! yes i tried this and totally ruined a fork!!!!

cooldad

flateric wrote:

Cant add much other than this. If you need to cut your fork length down, the steerer bit, FFS DO NOT HACKSAW IT!!! yes i tried this and totally ruined a fork!!!!

Hacksaw is the best way, what would you suggest?

Blue Meanie

Hacksaw is the best way, what would you suggest?

Sharp Stanley Knife? Good for scribing a line and stops carbon steerers fraying. Or the good old wrap of insulating tape if you don't have a guide.

My Techie teacher from High School insisted on turning the hacksaw blades the wrong way round, as it'll cut slower and is less likely to snag/snap the blade - I used to bring my own blades instead.
Trigger finger out, use full length of the blade and don't go too fast (remember to breathe)

flateric

Well, personnally ending up with a rough end which wasnt even flat and had loads of sharp edges didnt really go well for me so i would opt for a different method, such as a tube cutting tool.

Otherwise i would be asking my bike shop nicely to cut it down to length for me, which even after paying them is going to be cheaper than replacing the fork.

Never tried a carbon fork, and unless i could try a practice run on another fork, i would shy away from trying, mainly the cost if it goes wrong!!

Maybe its just me, but there are in my opinion some jobs not worth attempting unless you are very good at cutting tubes straight and true every time.

cooldad

Using a hacksaw is hardly rocket science. And a steerer tube doesn't need to be cut perfectly anyway. It doesn't touch anything. As long as it's straight enough to leave enough of a gap to the top cap it will work fine. The starnut need to be straight.
And the OP is looking for cheap and cheerful, no mention of carbon, which incidentally, is really easy to cut with a hacksaw, it cuts like plastic.

Gussio

£50 should buy you a pair of Kona P2's, which are designed to have a similar rake to your suspension forks. Probably save you a Kg and make the steering feel much more direct. They come in either canti or disc specific models.

Before cutting anything, make sure that you are happy with the steerer height. You can experiment with more or less spacers above and below the stem. When you do come to cut, don't be scared to use a hacksaw (I use a full-size rather than junior hacksaw) - as said above, the top of the steerer doesn't touch anything. Any rough edges can be removed with a file.

Good luck.

pulck

Thanks for the replies.

Threaded versus threadless, does your bike have a large nut round the steerer just above the headset, if so it is threaded, if not and the stem clamps round the steerer it is threadless.

If it is threaded you need to measure the outside diameter of the steerer just above said nut, if its threadless (probably 1 1/8) then remove the top cap and measure the inside diameter of the STEM (thus the outside diameter of the steerer it is wrapped around) then refit the top cap.

I looked today at my headset - and I'm probably being dim - but is this threadless...?



Assuming that it was threadless, I took off the top cap and measured inside: 1 inch....



(Sorry for terrible pics)

£50 should buy you a pair of Kona P2's, which are designed to have a similar rake to your suspension forks. Probably save you a Kg and make the steering feel much more direct. They come in either canti or disc specific models.

I have heard of the Kona P2s but I cannot see them brand new on any of the obvious online stores, only on ebay. Are they still in production?

Other consideration were Surly Cross or Pacer forks. Any cop? Suitable for a commuter hybrid?

Gussio

Cycle Surgery (£75) http://www.cyclesurgery.com/kona-p2-s/butt-mtb-rigid-fork/mtb-forks/bikes-components-bikewear/fcp-product/11413

eBay may be a source for you?

pulck

Gussio wrote:

Cycle Surgery (£75) http://www.cyclesurgery.com/kona-p2-s/butt-mtb-rigid-fork/mtb-forks/bikes-components-bikewear/fcp-product/11413

Thanks. I saw those, but sadly they are for 26" wheels and 1 1/8" steerer. Will check out ebay, but of course most of those are secondhand.

The Rookie

pulck wrote:

Assuming that it was threadless, I took off the top cap and measured inside: 1 inch....

Across the inside of the STEM, the end of that measure is on the inside of the steerer.......

Simon

pulck

Across the inside of the STEM, the end of that measure is on the inside of the steerer.......

Simon

Ah, okay! Hadn't quite appreciated the difference.

So was I right in thinking this is threadless? Again, apologies if this sounds very dim.

The Rookie

Yes it is threadless (sorry)....looks 1 1/8 but hard to say until measured properly.

Simon

optimisticbiker

You can't accurately differentiate between 1" and 11/8" with a tape measure, you need a proper steel ruler or better a 150mm digital calipers (about £6 off ebay) - you'll be amazed at what you can measure with them

The Rookie

OptimisticBiker wrote:

You can't accurately differentiate between 1" and 11/8" with a tape measure, you need a proper steel ruler or better a 150mm digital calipers (about £6 off ebay) - you'll be amazed at what you can measure with them

Using a normal 12" ruler you can't see a difference of over 3mm - well I feel sorry for you, I find it pretty easy myself!

Simon

pulck

OptimisticBiker wrote:

You can't accurately differentiate between 1" and 11/8" with a tape measure, you need a proper steel ruler or better a 150mm digital calipers (about £6 off ebay) - you'll be amazed at what you can measure with them

Is this any better?



Looks like 1 1/8" now.

The Rookie

Yup, 1 1/8" for sure.

Simon

Salsa

Be quick as these bargain Project 2 forks are obsolete on chain reaction but people keep buying them assuming they're the 26" version & returning them, so there's probably only one set left. They are V brake compatible even though the Spanish review says they aren't as I bought a set a couple of weeks back.
http://www.chainreactioncycles.com/Mode ... elID=71942

pulck

Salsa wrote:

Be quick as these bargain Project 2 forks are obsolete on chain reaction but people keep buying them assuming they're the 26" version & returning them, so there's probably only one set left. They are V brake compatible even though the Spanish review says they aren't as I bought a set a couple of weeks back.
http://www.chainreactioncycles.com/Mode ... elID=71942

That's great! Have just ordered and it was indeed the last one left. Many thanks.

pulck

Ok, I have only just got round to trying to replace my fork... and I'm afraid I have more questions.

Firstly, I believe the rigid fork I've bought is the wrong size to replace my old suspension fork:

Hopefully - despite my abysmal photography - you can see the distance from the axle to the crown on the old suspension fork (left, with the mudguard) is much longer (about 45cm) than that on the rigid fork (right, with the wheel in it) which is about 36cm. So presumably if I were to cut the steerer to the same length as the old fork, the bike's geometry would be totally out of whack. Does that mean I've got to find a different replacement fork? And should I be looking for a rigid fork with an axle to crown measure of 45cm?

Secondly do I see no way to remove my old star nut:

Nor do I see any way to remove the crown race from the old fork without a dedicated tool. So basically am I looking at buying a whole new headset? And does that mean I have to buy a set of tools to fit the new star nut, crown race etc?

Choosing a new headset is presumably a minefield for a novice. Any obvious choices for a commuter on a low budget?

Sorry if these questions sound dumb but I'm keen to learn.

supersonic

What are the exact crown to axle measurements? I can't see the top of the Kona fork in the pic, and the axle is lower anyway, making the sus fork look a lot longer. Are you sure it is a 700c fork, are the V brake mounts in the correct place? Round about a 400-420mm sounds about right for what you need.

Star nuts can't be reused in another fork.

Crown race can be removed with a hammer and screwdriver, though be careful!

pulck

supersonic wrote:

What are the exact crown to axle measurements? I can't see the top of the Kona fork in the pic, and the axle is lower anyway, making the sus fork look a lot longer. Are you sure it is a 700c fork, are the V brake mounts in the correct place? Round about a 400-420mm sounds about right for what you need.

Thanks for your response. It is definitely a 700c fork. It said so on the label. And the brake mounts are also in the right place - the brakes hit the rim correctly.

I measured the axle to crown incorrectly before (from the bottom of the crown rather than from the top). By my reckoning, the a2c on the old suspension fork (uncompressed, naturally) is 48cm. I cannot see a way of being more precise than this, as I'm holding the ruler parallel to the dropouts and so have to do some guesswork as to where the centre of the axle is. Is there a more accurate way of measuring the a2c, and ultimately does it need to be any more precise than that?

According to the Chain Reaction product page - http://www.chainreactioncycles.com/Models.aspx?ModelID=71942 - the Kona P2 has an a2c of 400mm. I'm assuming the 80mm difference between the 2 forks is too great?

supersonic wrote:

Star nuts can't be reused in another fork.

Crown race can be removed with a hammer and screwdriver, though be careful!

Even if I manage to remove the crown race, presumably I can't refit it to the new fork unless I have a special tool?

What I hadn't appreciated when undertaking to replace my fork is that I would have to replace some of the headset. It means it will work out far more expensive than I'd imagined and is probably going to be another minefield in itself -I have little to no idea what I'm looking for in terms of a new headset.... So is my conclusion correct that replacing the fork is ultimately best left to the professionals or at least to the highly qualified/well equipped enthusiast?

supersonic

You don't have to replace any of the headset (unless you include the star nut, which is a £2 piece) - transferring the crown race is all you have to do. A slide hammer is the correct tool, but a suitably sized piece of pipe or hammer and tapping often works.

I'd try and fit them and see how it feels to ride.

pulck

Thanks for for your help. I've ordered a cheap star nut. Am I right in thinking I can install it with just a hammer and screwdriver?

The crown race... looking around online it looks like removing it with a hammer and screwdriver is a risky affair. There are some available on Chain Reaction for £5. What do I need to know in order to pick the right for my headset?

When I come to install the crown race, rather than use a piece of pipe, would this £10 slide hammer do the job http://www.amazon.co.uk/Silverline-380625-Dent-Repair-Kit/dp/B002BSH0EI/ref=sr_1_1?s=automotive&ie=UTF8&qid=1329948962&sr=1-1?

£10 doesn't sound like too big an investment if I can be sure to get it done properly.

And lastly... I could potentially keep the bike's geometry the same if I insert 80mm worth of spacers above the head tube. Is there any reason why this is a bad idea?

(I realise I'm asking a lot of silly questions, so thanks for bearing with me.)

supersonic

To install a starnut, see here:

http://www.youtube.com/watch?v=q7F8BnCcetk

It has to be a headset crown race slide hammer like this:

http://www.billys.co.uk/english/group.php?prod=2br-sh

The crown race must match, and as are 100s of headsets, is very hard to find replacements for some. What is the headset?

The fork angle will be steeper regardless. 50mm of spacers max for height adjustment of bars.

pulck

Thanks, this is all very helpful.

My bike is 6 years old and was cheap, so I'd imagine the headset is pretty awful. Would it just be wise to get something new? Looking on CRC, how about something like this... http://www.chainreactioncycles.com/Models.aspx?ModelID=1066
and its crown race... http://www.chainreactioncycles.com/Models.aspx?ModelID=4039

supersonic wrote:

It has to be a headset crown race slide hammer like this:

http://www.billys.co.uk/english/group.php?prod=2br-sh

£25 is a bit much for a one-off job. Looks like I need to take a trip down B&Q.