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the 'there's no such thing as a stupid question' bike maintenance thread



  • Registered Users Posts: 554 ✭✭✭ARX

    I got them from Just Riding Along in the UK - the rim profile is below (nominal external width is 25 mm)./

    I measured the external width of the rim at the point nearest the hub and the point nearest the tyre at 4 points 90 degrees apart.

    I did this twice: once with the tyre fully deflated and once with the tyre inflated to 80 PSI.

    Deflated, width nearest hub: 24.15 mm

    Deflated, width nearest tyre: 24.3 mm

    Inflated, width nearest hub: 24.2 mm

    Inflated, width nearest tyre: 24.9 mm

    So the the part of the rim nearest the tyre is pushed out by 0.7 mm when the tyre is inflated to 80 PSI.

    For comparison, I did the same with a cheap Cannondale stock rim and found that in the deflated state, the corresponding figures are 24.9 and 25.0 mm, and in the inflated state they are 25.0 and 25.4 mm (so the rim is pushed out by 0.4 mm).

    So the rim is deformed by the tyre pressure, which I guess makes sense, although I'm a bit surprised that it's as much as 0.7 mm.

    At a guess, the braking surfaces were parallel before a tyre was mounted and were permanently deformed by the tyre pressure, and now do not return completely to their original form when the tyre is deflated.

    @CramCycle I have some old Shimano brake shoes so I will try your suggestion, thanks for that.

  • Registered Users Posts: 919 ✭✭✭nicksnikita

    I had a similar sounding issue on an old Ultegra mech.

    The pivot was part-seized. it baffled me for ages. I had to strip, flush, regrease and rebuild the mech which solved the issue.

    Id say this would only be relevant if the mech has been well used in mixed conditions. Any way you could swap in a mech that you know is good?

  • Moderators, Sports Moderators Posts: 24,402 Mod ✭✭✭✭CramCycle

    I wouldn't be over the moon with that either, but maybe that is why they are so light. I immediately thought they might be hookless and you over inflated them but alas no. Next best guess is to bite the bullet and ask the company directly, is this expected or tolerable. Better from them than a randomer on the internet.

  • Moderators, Sports Moderators Posts: 24,402 Mod ✭✭✭✭CramCycle

    Stupid question time, I want a fixed cog that attaches to my disc brake mount points. Found a few but I have some old cogs and am thinking, can i simply just drill them myself. Easy to mark, they are all hardened steel so shouldn't affect integrity. Can anyone tell me why I shouldn't do this?

  • Registered Users Posts: 282 ✭✭EAFC_rdfl

    My chain went loose all of a sudden Sunday, I managed to stay going by keeping to the middle of the cassette. If I shift down to the smaller cogs it results in a lot of play in the chain.

    Is it likely to be something gone wrong with the derailleur?

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  • Moderators, Sports Moderators Posts: 24,402 Mod ✭✭✭✭CramCycle

    Can you be more descriptive when you say loose? Is it bouncing around, kinking, swaying ? Do you have you a chain wear tool? How long has it been since you replaced the chain or cassette? Sorry for all the questions but pictures or a video might make it easier but the obvious guess is chain or cassette wear, but there are other possibilities.

  • Registered Users Posts: 919 ✭✭✭nicksnikita

    It could be that your derailleur pivot has seized. Try having a look at the derailleur as you shift gears (you may need spare hands or a bike stand) and see if it’s pivoting or try moving it by hand and see is it stiff

  • Registered Users Posts: 24,947 ✭✭✭✭Wishbone Ash

    It sounds like the spring tension in the RD is weakened. Do you ensure that the chain is on small cog/small cog when the bike is not in use?

  • Registered Users Posts: 1,584 ✭✭✭traco

    Where are guys finding the nest value for bike parts on line post Brexit?

    Want to get a new set of cables for the local hack as shifting has become clunky and its on original cables which must be 10 years old. Hoping it will be a cheap upgrade and transform it.


  • Registered Users Posts: 554 ✭✭✭ARX

    Germany - it's been cheaper to get stuff from there than the UK for years.

    Try,,,, Also in the Netherlands.

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  • Registered Users Posts: 1,584 ✭✭✭traco

    Cheers - order placed with bike24. When you mentioned them I though they sounded familair so had all my info. Easy decison although I may have saved a few euro if I bothered to look. Thought they prices were reasonale enough so ran with it.

  • Registered Users Posts: 282 ✭✭EAFC_rdfl

    thanks for the replies on this, I needed a day to get my hands on a chain ware gauge. Chain may well be the problem so will start with changing that.

    Leaving the bike in small ring, small cog is a new piece of advise for me. It's not something anyone had mentioned to me before!

  • Moderators, Sports Moderators Posts: 24,402 Mod ✭✭✭✭CramCycle

    Not sure the small small recommendation is a major concern for anything other than long term storage

  • Registered Users Posts: 490 ✭✭Antipathetic

    Stupidly ham-fisted installing handlebars on a bike and ended up stripping one of the threads that connects the handlebar clamp/ stem faceplate to the stem.

    Think it was because I forgot to lock my torque wrench and ended up over tightening one of the bolts. Or it was just bad luck.

    Would it be worth going to a bike mechanic to get a helicoil put in in order to fix the issue? Or is there something I can do easily from home? Or should I just replace the entire stem as it is about 20 euros to buy a new one?

    Don't let the terrorists in Israel win. Please donate to UNRWA now!

  • Registered Users Posts: 7,857 ✭✭✭cletus

    I'm all for DIY solutions, but in this instance new stem all day long

  • Moderators, Sports Moderators Posts: 24,402 Mod ✭✭✭✭CramCycle

    If the stem is only €20, it's not worth the hassle / cost to save 10euro for the feeling of not being confident.

    I'd do it but I am a cheapskate.

  • Moderators, Sports Moderators Posts: 19,693 Mod ✭✭✭✭Weepsie

    Have a short cage rear derailleur and a 52/36 chainset on a bike. Thinking of sticking long cage and a 50/34 on.

    How likely is it I will have to change the chain?

    Ultimately I will if/when I get a bigger cassette. alternatively just suck it up as is.

  • Registered Users Posts: 3,093 ✭✭✭seanin4711

    morning all,

    have a sram rival 10 speed med cage derailleur.

    looking to max out cassette on rear- front is a 130bcd 53/39 .

    can i go to 32T or more?



  • Registered Users Posts: 3,093 ✭✭✭seanin4711

    avoid bikeinn- they may look cheap but the customer service is shocking and delivery times not great

  • Registered Users Posts: 490 ✭✭Antipathetic

    I have been in touch with Decathlons support in Dublin about purchasing a new compatible stem and this is the one that they advised me to buy. However, I have my doubts as it looks completely different to what came with the bike.

    However it seems like this would be close to the original. Although, unfortunately, it is out of stock.

    Here is the original that I managed to break.

    Probably not wise but I have been riding the bike. I've made sure that the three remaining screws are talked up to the correct setting and I regularly check to make sure they are tight after every ride and so far nothing has gone wrong. And I am being cautious to avoid potholes and uneven terrain as much as possible.

    Don't let the terrorists in Israel win. Please donate to UNRWA now!

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  • Registered Users Posts: 7,857 ✭✭✭cletus

    It looks like an 80mm stem on your bike. Pretty much any 80mm stem will do as a replacement.

  • Registered Users Posts: 554 ✭✭✭ARX

    They can be slow all right but I've used them several times and never had a problem - I haven't had to use their customer service though.

  • Registered Users Posts: 3,093 ✭✭✭seanin4711

    order 1 = ordered folding tyres (advertised as folding) got wired and customer service/communication - null and void

    order 2 = ordered turbo trainer adapters (needed these for TA bike) and ordered a few more bits to make it worthwhile.

    they did have adapters in stock-fine i thought but it took almost a month from ordering to receive goods as their website had adapters in stock ,but then they couldn't source them, held up overall delivery by said amount.

    Communication is absolutely shocking and if you want to return an item or get a refund ,will never happen.

    look elsewhere!

  • Registered Users Posts: 406 ✭✭ofthelord

    Hi All,

    A couple of questions for you;

    I need a new Skid Plate for a Tiagra front derailleur. I had to google what the part was called, have never needed to replace one before but the one on my gravel bike has worn through so the chain is rubbing on the metal of the derailleur when shifting up. Have some black masking tape wrapped over it at the minute but expect it'll wear through that in no time. It is a very cheap part, but wondering if anyone can recommend where might be best to order from? It is the delivery charge for the part which is varying so much from the results I've seen on google.

    Also, I've a Box Four 8 Speed shifter on my mountain bike, and it has stopped working mid spin last week. Got stuck in lowest gear and will not shift up to bigger rings. I've opened up the shifter and can see that the mechanism is sliding over the cog it needs to engage to shift the gears up into the bigger ring. As it is sliding over the bit it needs to engage, I've tried tightening the inner workings with no luck. I'm not sure with this if it is something that can be fixed or if the shifter is end of life (bike less than a year old and gets least usage by far out of the 3 bikes), and if it can be fixed is something I can DIY or if a job for the local bike shop? It is a cheap enough bit of kit if I was to replace the shifter, but can't see anywhere in Ireland that has is stocked. Appreciate any advice on this also if it is something any of you guys have experienced yourselves.


  • Registered Users Posts: 7,857 ✭✭✭cletus

    I was out in the shed, cleaning the drivetrain on my bike, and having a few beers.

    I decided to take the cranks off, and I noticed that the drive side bearing was a bit rough (non-drive side is fine).

    I have this multitool, which fits into the hollow tech crank.

    It seems that the tool has been keeping water sitting just inside the crank, which has caused the bearing to wear prematurely.

    Now for the stupid question. Is there an easy way to know what bearing I need before I remove it, so that I can continue to ride the bike until I manage to source one?

  • Registered Users Posts: 5,110 ✭✭✭nilhg

    That's a Praxis crank? Presumably a hollowtech compatible one? I'm fairly certain that your Giant will have a BB86/92 pressfit BB, if you're stuck I have a spare here.

    Water inside the axle shouldn't cause the bearing outside the axle to go though?

  • Registered Users Posts: 7,857 ✭✭✭cletus

    Thanks for the reply, Nilhg.

    I think this BB is BSA, threaded.

    I think what's actually happened is that the placement of the multitool allowed water to wick into the cup holding the bearing itself, rather than just sitting along the axle.

    Could be wrong about that, though, it was just my first thought on pulling the crank.

    Anyway, if it is BSA BB, am I looking at an M30 bearing, or are there other options

  • Registered Users Posts: 5,110 ✭✭✭nilhg

    If it's a standard english threaded 68mm BB then there's no point trying the change the individual bearings, just get the complete package and swap the whole thing, they're not particularly expensive. I doubt you'd get a thirdparty bearing to fit in the cups the same as the factory fitted one.

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  • Registered Users Posts: 5,110 ✭✭✭nilhg

    Definitely not hollowtech compatible so, it's 24mm spindle yours seems to be 30mm.

    Your problem will be that you'll have to remove a bearing to measure it, then source one and fit it, much handier to just buy one complete but that conveniennce does lead to waste, it's true.

    found this, seems to be what you want?