CityCyclingEdinburgh Forum » Questions/Support/Help

Help. Rim help needed.

(25 posts)
  • Started 10 years ago by DaveC
  • Latest reply from chdot
  • This topic is not resolved

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  1. DaveC
    Member

    I have a wheel from a collegue which has been given to me. Its slightly warped and quite worn. I'd ideally like to pop a new rim on it and re use the spokes if possible. I know the spokes will be weakened by the existing rim and use but I'm on a budget. Its off a ~2010 Ridley Crossbow, and is a Pro Bike R35 rim with double butted spokes on a Tiagra hub. If I can lace across a new rim this would be the cheapest option. Its never going to be a premium wheel, but something I can use a s a spare, say in winter with a studded tyre on, which I can swap over if needed (ignoring the cassette problem for now!)

    I'm having problems finding a PRO Bike R35 rim and wonder if there is a tool online which I could use to find an identical rim so I don't have to fork out for new spokes.

    Anyone able to help please?

    Dave C

    Posted 10 years ago #

  2. allebong
    Member

    Haven't turned up much info on that rim from a quick search myself, appears to be a Shimano OEM part.

    If you can find a new rim with the same ERD then reusing the spokes shouldn't be an issue unless they've been very heavily used indeed. Though according to a wheelbuilding guide I'm reading at this very minute what the rim manufacturers state as the ERD should not be trusted and you need to measure it yourself, but that doesn't help you buying a new rim and knowing for sure what you're going to get.

    If it isn't going to be a premium wheel as you say, then for around £5 you can get a whole set of plain gauge stainless spokes, they come without nipples but you should be able to reuse the ones off the wheel, failing that I have tons of spare ones lying about at the moment you're welcome to have if needed.

    Also, I've just dismantled a 700c disc wheel for spares, was only interested in the hub so have the rim and spokes available, will get some measurements if you want (disc only rim though, won't work with rim brakes).

    Posted 10 years ago #

  3. Cyclops
    Member

    The rim may well be something from one of the major manufacturers that's been re-badged but as Pro have likely removed all identifying marks figuring out which may be tricky. I suspect trying to buy the R35 rim as an OEM part may be equally difficult as the wheel was last manufactured several years ago so allebong's suggestion of a new rim with the same ERD sounds the simplest solution.

    Posted 10 years ago #

  4. DaveC
    Member

    Hmm, thanks for the suggestions. I'll have a google of measuring the ERD then. I can get plain gauge spokes from my LBS easy enough. I didn't know plain gauge spoke were cheap? I assumed they might be marginally cheaper than double butted which are around 70 pence each (though may have gone up in the last year).

    Posted 10 years ago #

  5. Cyclops
    Member

    You could of course do it slightly backwards - measure the spoke length and then you can work out a range of rim ERDs that should work with your existing hub/spoke combination.

    Posted 10 years ago #

  6. I were right about that saddle
    Member

    In my experience rims tend not to get worn without the hub getting similarly eroded, so maybe watch you're not putting a new rim onto a shonky hub. That'd likely be a false economy. It might be worthwhile doing a hub service to check for pitting on the rolling surfaces first.

    Posted 10 years ago #

  7. wingpig
    Member

    "I can get plain gauge spokes from my LBS easy enough. I didn't know plain gauge spoke were cheap? I assumed they might be marginally cheaper than double butted which are around 70 pence each (though may have gone up in the last year). "

    1: Support your LBS by all means but buying a wheelsworth of spokes from them at 70p each is pricey, though...
    2: beware cheap spokes. My current stop-gap wheel was a salvage/rebuild using cheap plainguage and has a habit of popping spokes when I'm doing something they find excessively taxing, such as riding without extra luggage on a smooth flat surface.

    Posted 10 years ago #

  8. DaveC
    Member

    Cheers guys. I can bring the wheel along next weekend cyclops if you want? Its on a Tiagra hub. I was thinking of buying plain gauge spokes wingpig. So you think plain gauge are a false economy?

    Dave C

    Posted 10 years ago #

  9. wingpig
    Member

    "I was thinking of buying plain gauge spokes wingpig. So you think plain gauge are a false economy?"

    'beware cheap spokes', meaning budget spokes rather than reputable spokes acquired inexpensively.

    Posted 10 years ago #

  10. allebong
    Member

    Nothing wrong with plaingauge, I've got several basic wheels laced with them that have taken some severe batterings, that said when I come to respoke them I'll probably go for double butted because it's only a ~£15 difference. The DT Swiss ones I linked to earlier are certainly a reputable make, though who knows about the individual spokes.

    It might be worthwhile doing a hub service to check for pitting on the rolling surfaces first.

    Good point, it's definitely worth inspecting the hub and checking for any obvious looseness or damage to the freehub as well. In my experience a decent hub properly cared for will easily outlast many rims though that is dependent on the decent part (some unbranded OEM hubs can be rather poorly sealed) and moreso the properly cared for part (every single hub I've ever bought on it's own, or as part of a wheel/bike, has been badly undergreased and overtightened, which is a sure fire recipe for rapid permanent damage).

    Posted 10 years ago #

  11. Arellcat
    Moderator

    In my experience rims tend not to get worn without the hub getting similarly eroded,

    The other aspect is that the hub flanges will have bedded in with the existing spoke lacing pattern, and a complete respoking needs to respect that. However if the rim is being replaced with one of a sensibly similar ERD then it's a straight migration of spoke ends from one to the other.

    DaveC, I use a long piece of piano wire, calibrated for length and with a spoke nipple soldered to one end and a drilled-out spoke nipple floating on the other end. You just add a proper steel ruler to determine the ERD. It works much like Wheelsmith's Rim Rods. You could try Spocalc for a database of rims.

    Posted 10 years ago #

  12. Instography
    Member

    I've built seven wheel on plain gauge spokes and not had any problems. All bought off eBay (http://www.ebay.co.uk/usr/spokesave) for pennies. At this price you shouldn't even think about reusing spokes.

    Bear in mind, for those who know me, that these guys are carrying my weight so they're earning their keep.

    For my money, it's all about minimal tensioning.

    Posted 10 years ago #

  13. wingpig
    Member

    For no swearing's sake.
    I have no barney with plainguage. Sparebike is full of plainguage DTs and is fine, despite only being used for weight-intensive tasks. I have had almost an entire wheelful of cheap plainguage spokes pop at me from the rear wheel of normalbike, even though I only weigh ¾ Instogrammes. I don't know where they came from originally as I bought them secondhand.
    I tried a minimally-tensioned wheel for a couple of weeks which is probably how the rim survived the wheel eating the rear mech, as all the spokes had room to bend significantly without overtightening.

    Posted 10 years ago #

  14. Instography
    Member

    I'd bet half.

    Posted 10 years ago #

  15. steveo
    Member

    Wingpig, those the spokes you got from my misadventure in spoke measuring? I got those from the chap insto linked too. I've had no trouble with mine in the front dynamo wheel n the fixed despite being ~1 instography though i do only 1/4 insto-miles.

    Posted 10 years ago #

  16. wee folding bike
    Member

    Tell me more of this minimal tension. I thought they needed to be very tense so that they remain under tension at the bottom of the wheel. By minimal do you mean just enough tension so that they are not loose at the bottom of the wheel when the axle is loaded?

    Posted 10 years ago #

  17. wingpig
    Member

    "C4 on the drive side and the Bb below C4 on the other side"

    ~Insto

    My frequent-O-pop wheel was a bit higher.

    @steveo Yes, but this was on a rear, salvaging a previously-used rim.

    Posted 10 years ago #

  18. Arellcat
    Moderator

    For my money, it's all about minimal tensioning.

    For my money, it's all about maximal tensioning, to the limits of either the rim's compressive strength or the toughness of the spoke nipples.

    A wheel is a pre-stressed structure and minimal tensioning could risk some spokes being unloaded completely which would overstress adjacent spokes and lead to decreased durability of the wheel. As for plain vs. butted, it depends on how many miles the wheel is expected to cover and over what time period. Plain is cheaper but butted is more durable because the stresses occur in the middle of the spoke and not at the bent end or the threaded end.

    Posted 10 years ago #

  19. chdot
    Admin

    "For my money, it's all about maximal tensioning, to the limits of either the rim's compressive strength or the toughness of the spoke nipples."

    Not too tight.

    "butted is more durable because the stresses occur in the middle of the spoke and not at the bent end or the threaded end"

    Don't understand that in theory or reality.

    I thought the 'main' point of d/b was weight reduction - on the basis that strength was required at the ends.

    I have had spokes break in the thin section, but generally it's the bend at the hub.

    One factor there is the width of the hub flange.

    A thinner flange weighs less but can contribute to spoke breakage.

    It was once 'common' to add a brass washer next to the spoke head.

    In 'the past' one good reason for choosing d/b was that they were likely to be higher quality steel/better made.

    These days (certainly for mountain bike use) strength is more important than slight weight saving.

    Spokes can be expensive, but - to some extent - depends on relative cost of rim, hub & tyre.

    Posted 10 years ago #

  20. Instography
    Member

    OK. I don't know enough to argue. All I can say is that after truing them when they were built (Aug 2012) I've never had to touch the spokes again.

    Posted 10 years ago #

  21. allebong
    Member

    I'm just getting into wheelbuilding, and I've been reading the excellent Roger Musson guide, among the things he mentions is that any internet discussion regarding the theory or practice of the art is going to throw up all manner of disagreement.

    Double butted vs plaingauge, from my (limited) understanding, it's very little to do with weight, and everything to do with durability. The thinner middle section allows the spoke to stretch more and share the load with neighboring spokes thus actually improving strength and fatigue resistance, somewhat counter-intuitively.

    This is also the first I've read of 'minimal' tensioning, basically every source I've come across holds that the spokes should be pretty tight, or at the least not ever approaching loose.


    These days (certainly for mountain bike use) strength is more important than slight weight saving.

    Never underestimate the determination of a weight weenie, though they are less common on the dirty side of cycling.

    Mtb wheels are funny things. They get used with very wide tyres and very low pressures, with suspension, so with any halfway decent rider that can unweight over the worst bumps they are probably seeing much less stress than a 23c road wheel that has to deal with typical Edinburgh streets full of cobbles, potholes and kerbs etc. On the other hand, when you get a bit too ambitious offroad, the wheels tend to be the first thing to collapse. Classics include: Landing sideways (crunch), landing onto a sharp edged rock or root (clang), having the mech get bashed into the spokes with predictable consequences (mostly including uttering of bad words).

    So you get this weird situation where you're not really worrying about long term fatigue life, because it's very unlikely the spokes are going to give out before the rim gets permanently damaged, but you are worrying that the wheel will go from totally fine to totally totalled in a split second. Example:

    This guy was landing from a jump and came down on his front wheel (bad) with it angled (very bad), the result being the wheel getting tucked under the front of the bike and him getting catapulted over the bars. That's beyond the help of any amount of spoke key wizardry I think.

    Posted 10 years ago #

  22. le_soigneur
    Member

    @chdot The point of DB is NOT weight saving, It is precisely because of the thinner mid-section that the spoke can stretch and avoid reaching critical stress. Because the mid-section has no corners/edges, it can take a lot more stress without reaching elastic limit.
    The elbow and nipple ends DO have edges and corners which act as stress concentrators and therefore need to be full guage at these points. Even so, on a straight guage spoke they always reach elastic limit before the ied-section, and that is always where they yield to fail.
    Double-butted spokes soften the stress on the ends by deliberately yielding at the middle, but not to failure. It is a bit like having a spring in the middle of the spoke to absorb shock.
    Useful reading: The Bicycle Wheel by Jobst Brandt
    (@ Allebong Apologies for duplication, you posted simultaneously, but no harm to back up what you say)

    Posted 10 years ago #

  23. Instography
    Member

    When I say minimal, I don't mean rattling around in the rim. I mean only just sufficiently tight to have each spoke tight enough to pluck and the wheel true.

    Posted 10 years ago #

  24. Cyclingmollie
    Member

    @DaveC I know you don't want to spend much on this but perhaps you can get an answer from the Bicycleworks. I know someone who wore out a pair of RS80 rims; couldn't get replacements and didn't want to ditch the Ultegra level hubs. Bicycleworks found a pair of rims which fitted perfectly.

    Posted 10 years ago #

  25. chdot
    Admin

    "any internet discussion regarding the theory or practice of the art is going to throw up all manner of disagreement"

    Indeed, and we haven't even mentioned crossing, lacing or tieing!

    "@chdot The point of DB is NOT weight saving, It is precisely because of the thinner mid-section that the spoke can stretch and avoid reaching critical stress."

    Of course you are right in a technical sense.

    But realistically spokes don't break that often. D/b spokes break too - sometimes at the thick/thin junction.

    Butted spokes make wheels/bikes lighter more than replacing steel&chrome bottle cage bolts with aluminium or titanium ones!

    In the 'old days' front wheels had 32 spokes AND (sometimes) thinner 13/15 spokes. Rears were commonly 40 for extra strength where the drive forces and rider weight were.

    Then the 'continental' 36/36 became the norm - I presume this was for manufacturing convenience. Now almost anything goes. A lot of effort went into reducing air resistance, where fewer and thinner (and shaped) spokes would make a difference, but probably more effort went into rim profiles.

    Generally rims became stiffer - due to design (notably double wall rims) and materials.

    So in many ways spokes are less important - just make sure your rear mech doesn't go into them...

    Most of the above refer to racing/sport where speed, competitive advantage, fashion, vanity etc. are factors. Practical things like replacing a spoke in the dark and wet, or longevity, are less important!

    With lighter wheels there is also the bonus of reducing revolving weight. Though it's probably easier to consider tyre choice - then it's back to weight v punctureproofness (amongst other things!)

    Posted 10 years ago #

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