April 10, 2005

New bike bits; fitting

Popped over to Rich's fully-equipped garage to fit my new Fox forks yesterday. Removing the original Rockshox Pilots was fairly easy; undo the star-fangled nut, remove the stem, calipers, bearings and shims and the forks just pulled out. Removing the bearing outers needed careful persuasion with a hammer and some wood, but they eventually came out cleanly.

A quick wipe with degreaser and we were ready to fit the new headset. This is a WTB Momentum Comp C with sealed cartridge bearings, so the outers are somewhat larger than normal to make room, but I can live with that knowing they should be good for a while. Fitting the outers didn't cause too much bother – a hammer, some pieces of wood and constant checking to ensure they were going in square. Getting the star-fangled nut to go in was a different matter. The nut would not go in square, causing much frustration, but eventually it gave up the fight and went in nice and straight.

Now the best bit; offering up the new forks. We assembled the headset and pushed them through, then temporarily fitted the stem and marked the fork tube for cutting; Rich used a pipe cutter to reduce the tube to sit about 5–7mm below the headset cap – a nice clean cut that needed a minimum of filing. We tightened everything up, then loosely fitted the calipers; we needed to add an extra shim but that was the only adjustment needed to the brakes.

Swopping the original forks onto the Rockhopper was equally easy – I had to cut down the V-brake bosses to fit and just cleaned and regreased the old headset, but I reckon the bike will be transformed; the old Manitou Spyders were, frankly, knackered. 20mm extra travel and forks that actually move should make a difference.

Last job was to fit a new cassette to the Marin; I fitted a new XT chain last month for Afan and neglected to fit a new cassette at the same time; big mistake. For the first 6km climb the chain was jumping and ghost-shifting all the time, because the cassette had worn to the old chain. The new cassette is an SRAM PG-830, picked up at the Bike Show for £15. It's an 11–32 (the old one was 11–28) and not exactly light, but my experience of super-light components is that they break sooner than their price suggests; mid-range stuff like this is a better bet for me. The extra cogs will hopefully make a difference too. Fitting was a doddle with the right tools – a chain-whip and cassette tool, and took about 5 minutes.

I haven't taken either bike out for a decent test-run yet, but early impressions are that the Fox' are super-smooth, and more progressive than the Pilots, although they currently have a tiny bit of stiction at the beginning of their stroke. They also look fantastic. The Rockhopper seems a bit 'nose-high' at the moment, but a brief ride up the road indicates that it should be a much more capable ride over the rough stuff.

Thanks to Rich for all his expertise and help – hopefully we can test the bikes out properly at Cannock soon. Is it me or is the Marin crying out for some red Hope XCs and Salsas? :-)

- 21 comments by 4 or more people Not publicly viewable

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  1. Wow, your attitude to bike maintenance puts my "hit it with a hammer and cover it with oil" approach to shame.

    10 Apr 2005, 20:17

  2. Steven Carpenter

    That's pretty much what I'd have done otherwise :-)

    10 Apr 2005, 20:29

  3. Steve Rumsby

    Last job was to fit a new cassette to the Marin…

    Hmmm… my chain has probably been overworn for a little while now and I was planning on replacing it soon. I guess I will need to replace the cassette also. Any hints and tips for somebody who hasn't done this before?

    11 Apr 2005, 10:56

  4. Steven Carpenter

    Hi Steve – the cassette was really easy; buy a cassette adaptor and chain whip, remove the Q/R skewer, lock the chainwhip around the outer cog,, insert the cassette tool and undo the cassette; refitting (as the Haynes manuals say), is the reversal of removal (after a quick wipe-down of the hub casing). I'd recommend using a torque wrench (the SRAM says 40nm) to do it back up but my trusty mechanic has always just retightened them by hand - not too tight though! As he's been riding and servicing bikes fairly hard for 20 years I'm not going to argue. I think Chris has come across this problem before; always change the chain and cassette together!!

    11 Apr 2005, 14:26

  5. Steve Rumsby

    Thanks. The only problem I have now is finding a replacement cassette. My bike currently has a Shimano Megarange 7-speed (11–13-15–18-21–24-34) cassette, and I haven't found it so far in the online bike-shops I usually frequent. Might have to resort to a real bike-shop. I would go for something more conventional, but I've grown quite attached to that 34 tooth cog. It is probably making me lazy, but I don't care:-)

    11 Apr 2005, 15:39

  6. Steven Carpenter

    Would the SRAM PG730 7spd cassette (12–32) be a suitable alternative?

    11 Apr 2005, 20:03

  7. Steve Rumsby

    It might actually be an improvement. For a start, I won't get to be quite so lazy! Also, I think my current cassette is 14–34, not 11–34 as I said above, so the SRAM would give me a slightly higher top gear, which I've been thinking about anyway. Also, the jump to my current 34T from the next gear up is huge, and quite a shock when you decide to change up a gear! The SRAM looks to have more evenly spaced gears?

    Anyway, all the bits now ordered from wiggle, so I'll have to plan for some fun at the weekend:-) If it all goes horribly wrong, I'll sure I'll vent my frustrations in a blog not far from here…

    11 Apr 2005, 20:39

  8. Steven Carpenter

    Good luck – it should be fine. I feel quite liberated from the bike shop now, which I'm sure will last only until my headset comes to pieces in the middle of Wales…

    11 Apr 2005, 20:49

  9. Steve Rumsby

    It has only just occured to me to ask – if the cassette wears out with the chain, and should normally be replaced with it, what about the chainrings? I've never seen anybody mention replacing them when replacing a chain, so I guess not, but why not?

    12 Apr 2005, 13:35

  10. Steven Carpenter

    No idea; they don't seem to suffer as much, but presumably if you left them long enough on a worn chain they would eventually suffer. I have known people replace them because of wear, but the usual reason for replacing chainrings in the company I keep is because they've been clonked against a rock :-)

    12 Apr 2005, 22:14

  11. There's no reason to change the back sprockets if they are not worn. The usual problem is people let their chains get too worn before changing them. Once worn (i.e. elongated) at any moment the whole driving force is put on one back tooth and one front tooth. Then there's the excellent grinding paste of mud & oil/grease, it's no wonder that the teeth wear. I normally replace chains once they stretch by half a percent or more. A normal steel rule can be used to measure – each rivet was exactly half an inch from its neighbour when the chain was new. Measure a good length (50 inches?) so that the extension can be seen easily

    I have read that some people get 20,000 miles without replacing any sprocket and without problems. They change chains before they get too long and clean them even more frequently. But this is for bikes which they only ride on road. Clearly there's a lot more mud off road.

    18 Apr 2005, 11:54

  12. Chris May

    I started trying that approach (change chains frequently, cassettes rarely) on my (road) commmuting bike, but in the end it works out more expensive for me.

    With my rather idle once-a-week-ish maintanence routine, I can get 5,000 miles out of a chain+cassette before it gets unusable – cost of replacement about £60 *. OTOH my chains seem to be stretched past 0.5 percent after about 1000 miles – cost of replacement about £20. So it's either £60 / 5K or £140 / 5K (5 chains and a cassette). I guess if I were more fastidous about cleaning my bike they might last longer, but then I'd be spending even more on de-greaser!

    * HG70 cassette, SRAM PC950 chain

    Incidentally I've found on the road that alloy small chainrings wear out in about 5K or so, but steel ones appear to last forever.

    18 Apr 2005, 12:19

  13. Steven Carpenter

    The off-road use certainly accelerates the wear; in part this is due to the mud/oil/grease, but there's probably more stress on the chainset as a whole, over a given distance.

    18 Apr 2005, 13:14

  14. Interesting discrepancy regarding chain wear. My touring bicycle is on its fourth chain and second cassette after 15,000 miles. I've replaced the smallest front sprocket once. I aim to run chain, back and front sprockets into the ground and replace the lot, I hope not before 18,000 miles.

    Perhaps lifetimes vary with brand. I thinking bicycle components come in three grades: toy (soft, cheap), reliable (long lasting, medium price), yuppie (short life, light).

    However this is strictly a fair weather bike. I'm rarely go out on it when its raining. Also I don't use oil – I use the old motorcyclists' method. Every couple of thousand miles I do a total clean with chain off bicycle using solvents and then use chain wax – basically a purpose made motorcycle chain lubricant. It's solid at room temperature but liquid at 120C – I pop the cleaned chain in the can into the oven. Leave for a few minutes and then remove excess lubricant. When cooled there's plenty of lubricant hidden away where it matters around the pins, but the chain is not at all sticky.

    See link

    I think nowadays there are lubricants which are liquid for a few minutes after they come out of the can, then the solvent evaporates leaving a dry but lubricating residue.

    As for pottering around town – I use an enclosed chain hub gear bike. No greasy right leg, no bicycle clips, no dirt on chain. Like in the Netherlands where everyone knows about bicycles! And indeed in the UK 50 years ago when people here knew about bikes!

    18 Apr 2005, 14:03

  15. Chris, perhaps your chains no good. What I used:

    Cassettes: Seven speed Shimano Hyperglide. FH-HG20, HG30 11/28 7 Speed Suntour (£13.50 not as hard wearing as the Shimano)
    Chains: 7 speed for £5 or £6 each.

    18 Apr 2005, 14:15

  16. Chris May

    It's possible, but I'd be disappointed if it turned out to be true true; SRAM stuff is generally pretty highly regarded (at least, in MTB circles it's usually ranked above shimano) and the 950s are a reasonably high-end chain.

    However, I suspect that the weather might be a bigger contibutor – this bike does 25 miles a day, monday to friday every week – so during the winter it has a fairly harsh time of it. I use a 9-speed setup, too, which is somewhat thinner (and therefore I guess less hardwearing) than your 7-speed chains

    The wax idea is an interesting one; I've experimented with wax-based lubes in the past but found them to wash off too easily resulting in chains that go orange between arival at 9am and departure at 5:30 – however I've not tried ones that are 'baked' on.

    18 Apr 2005, 18:54

  17. I posed this issue on the CTC bulletin board (link)

    Peddaling Pete gets 2750 miles of all-year riding from a chain. 8000 miles from the cassette and 20,000 from chain rings. 9 speed kit. Clearly with Shimano Ultegra he's using a road racing bike.

    Perhaps the answer lies in the cleaning and lubrication?

    19 Apr 2005, 22:09

  18. Steve Rumsby

    Perhaps the answer lies in the cleaning and lubrication?

    As the person who started all this off by asking for advice on changing a chain and cassette, I'll add another data point. My bike is about 3.5 years old, and has done about 4k miles, all on the road, in all weathers, and since moving to University House a year ago has been left outside in all weathers thanks to the University not putting a roof over the cycle hoops. Until the weekend it was on the original chain and cassette (actually freewheel, but that's another story). The chain was badly worn, and after getting advice both from cyclists here and elsewhere I decided to replace the cassette at the same time. Since it turns out I needed a freewheel and not a cassette, I only maganed to replace the chain over the weekend. Riding the bike in that condition on Monday was interesting. The freewheel is clearly badly worn too, and skips like crazy in the smaller gears. So I'm not riding it until I replace the freewheel (this evening, Wiggle permitting).

    In summary, after 4k miles my chain was shot, and sufficiently badly that it had killed the freewheel. Maybe if I'd changed the chain sooner, the freewheel would have survived? I'm certainly not that dilligent about cleaning it, which could be the problem, as you suggest. I'm not going to leave it so long next time (2k miles?) and we'll see what happens.

    The original freewheel is Shimano. The chain wasn't, but I'm not sure what it was. The new chain is Shimano.

    20 Apr 2005, 10:36

  19. Chris May

    Clearly with Shimano Ultegra he's using a road racing bike. Perhaps the answer lies in the cleaning and lubrication?

    Absolutely. Generalising in an unjustifiable way from my rather limited experience of them, 'roadies' tend to be super-fastidious about their bikes and polish them to within an inch of their lives after every ride.

    I on the other hand follow approximately the following routine;

    ((am ride->chuck in office corner->pm ride->chuck in shed) repeat 10 times); whizz chain through chaincleaner machine; repeat for a year.

    I'm absolutely certain that if I stripped the chain off after every ride, degreased and oiled it, it would last for ages longer – but to be honest £80 and an hours work once a year for a new drivetrain seems like a small price to pay for not having to do that.

    I also speculate that my 10* 13 miles a week might be more damaging than a club rider's 2*65 mile rides; though I'm not quite sure why that should be.

    20 Apr 2005, 20:36

  20. I accept your point. It's what led me to buy a bike with an enclosed chain for getting around town and reserve my sporty job for leisure cycling.

    My commute is only 6 miles each way, and it's urban (no long fast runs) so the other characteristics of my utility bike (sit up & beg handlebars, rather heavy, 37 mm tyres) cause no problem.

    21 Apr 2005, 18:25

  21. Another point has been raised:

    "the main thrower of grit onto chain is undoubtedly the front wheel – note the deposit of flotsam at the down-tube to bottom-bracket junction of any mudguardless bike after a mucky ride." So a front mudguard is critical.

    21 Apr 2005, 18:34

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