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

magicbastarder

i need to figure out a way of getting my rear disc brake assembly to sit higher on the bike - the pads are connecting with the disc probably a couple of mm closer to the axle than they should be. i guess it's just a case of adding a couple of washers to sit it higher? i can't see any dedicated height adjustment mechanism.

iwillhtfu

magicbastarder wrote: »

i need to figure out a way of getting my rear disc brake assembly to sit higher on the bike - the pads are connecting with the disc probably a couple of mm closer to the axle than they should be. i guess it's just a case of adding a couple of washers to sit it higher? i can't see any dedicated height adjustment mechanism.

Take off the washer from under the bolt head and place it underneath between the caliper and the frame. There's usually a couple in there to adjust the height.

magicbastarder

they're fine - the only issues i've had with them really are the normal things you'd expect with disc brakes. had an issue with contamination, but that was unrelated to the brakes themselves. one thing to watch out for is the adjustment barrel - it's for initial setup only, but if you start using it to adjust for pad wear, it can throw of the automatic adjustment mechanism; the brakes supposedly accoutn for pad wear themselves.

magicbastarder

iwillhtfu wrote: »

Take off the washer from under the bolt head and place it underneath between the caliper and the frame. There's usually a couple in there to adjust the height.

as it turns out, the washer on the bolt would not come off. found a few spare ones in the tool box anyway.

GeneralC

How/when do you know to change gears?

Type 17

When your cadence (pedalling rate) gets too slow/hard, shift down.
When it’s too fast/easy, shift up.
Ideal cadence is 75-90rpm (IMO - others may have differing opinions).

seamus

magicbastarder wrote: »

as it turns out, the washer on the bolt would not come off. found a few spare ones in the tool box anyway.

You should always have a washer between the bolt head and the unit anyway. Means you're less likely to damage stuff and less likely to have seized/fused bolts.

CramCycle

Type 17 wrote: »

When your cadence (pedalling rate) gets too slow/hard, shift down.
When it’s too fast/easy, shift up.
Ideal cadence is 75-90rpm (IMO - others may have differing opinions).

I would say the cadence depends as well on whether you want to push hard or not, lower cadences are fine if your not interested in speed and your not putting alot of force on your knees. Everyone can disagree with the following:

60 -75rpm - little force on the knees, happily tipping along at a casual pace - low gearing

70 - 90rpm - touring or commuting - a bit of force but not enough to make you blow up, tipping along nicely at 20 to 25kmph - middle gear range

90 - 110rpm - racing or fast commuting cadence - middle to high gearing depending on whether you are uphill or downhill.

I nearly stay around the 100rpm all the time and adjust the gears to keep me moving

magicbastarder

CramCycle wrote: »

60 -75rpm - little force on the knees, happily tipping along at a casual pace - low gearing

probably just worth clarifying that you can do this low cadence when there is little force on your knees, when you're just moseying along. choosing this cadence while trying to go fast by selecting a tough gear will actually put more force through your knees.

@GeneralC - you may see references to spinning and grinding. for a given speed, spinning would be choosing an easier gear and pedalling faster; grinding is when you choose a tough gear and pedal more slowly. the latter will tend to tire you out faster (within a reasonable range of cadences - you don't want to go to an extreme at either end of the range)

CramCycle

magicbastarder wrote: »

probably just worth clarifying that you can do this low cadence when there is little force on your knees, when you're just moseying along. choosing this cadence while trying to go fast by selecting a tough gear will actually put more force through your knees.

@GeneralC - you may see references to spinning and grinding. for a given speed, spinning would be choosing an easier gear and pedalling faster; grinding is when you choose a tough gear and pedal more slowly. the latter will tend to tire you out faster (within a reasonable range of cadences - you don't want to go to an extreme at either end of the range)

Pretty much what I meant, bar racing, if it is a tough slog or alot of effort through your body, drop gears until you can sit down and not wobble all over the place like you are climbing a mountain in a grand tour.

Speed should be the secondary consideration in cycling, as speed will come as the fitness, cadence and comfort increase.

dahat

CramCycle wrote: »

I would say the cadence depends as well on whether you want to push hard or not, lower cadences are fine if your not interested in speed and your not putting alot of force on your knees. Everyone can disagree with the following:

60 -75rpm - little force on the knees, happily tipping along at a casual pace - low gearing

70 - 90rpm - touring or commuting - a bit of force but not enough to make you blow up, tipping along nicely at 20 to 25kmph - middle gear range

90 - 110rpm - racing or fast commuting cadence - middle to high gearing depending on whether you are uphill or downhill.

I nearly stay around the 100rpm all the time and adjust the gears to keep me moving

100rpm, that's impressive.

I switched to 11/25 and as a consequencey cadence has dropped but each time I try the 11 28 again I suffer from cramps, during & after a spin.

CramCycle

dahat wrote: »

100rpm, that's impressive.

I switched to 11/25 and as a consequencey cadence has dropped but each time I try the 11 28 again I suffer from cramps, during & after a spin.

Same here, and I used to be a grinder for many years but have found since talking to people more knowledgeable than me that you have to spin it to win it, if your cadence is dropping then the gearing is to high. In sprints etc. that is fine, or making a break but you will burn off alot of the immediately available energy and are more likely to blow up IMO. Get used to a higher cadence at a lower gear (same overall speed) and I would be pretty sure you will see improvements. I say this knowing you are a faster and stronger racer than me.

Weepsie wrote: »

Shorter cranks maybe?

I went to 165mm and seen an instant reduction in issues. The jury is very out on it but my opinion would be down to a certain length (162.5 or 165mm), almost everyone should be fine but everyone has a max. Everyone kept saying I should be 175mm but I use 165mm and find spins in the same gearing on a bike with 175mm to be energy sapping.

Macy0161

Anyone know what the lowest standard shimano crankset that would have crank compatibility with ultegra/ 105 cranks? Tiagra 4700 does, but does the most recent Sora?

Not planning on doing it generally on the commute, but now I have a crank based power meter, I'd like the option of putting it on as that is the bike that comes on holiday. It's currently 9 speed, so a new BB/ crankset looks like the cheapest option. Struggling to justify a full Tiagra groupset, and it's an old enough frame (even though I really like it!). It'd be mainly for commuting, possible used to try cross in the Autumn and a few gravel/ fireroad spins.

Mikenesson

I can't quite tell if my pads are 52 or 55mm from the outside

Is it the length of the rubber insert from end to end?
Thanks

CramCycle

Mikenesson wrote: »

I can't quite tell if my pads are 52 or 55mm from the outside

Is it the length of the rubber insert from end to end?
Thanks

Yep, rubber insert length but remember, if your still not sure, you can trim down a 55 to 52, not the other way around

Mikenesson

CramCycle wrote: »

Yep, rubber insert length but remember, if your still not sure, you can trim down a 55 to 52, not the other way around

Are the shinano pads all the same design?

The ones I'm looking at seem to be the right ones, a slight taper on the width and a screw holding it

CramCycle

Mikenesson wrote: »

Are the shinano pads all the same design?

The ones I'm looking at seem to be the right ones, a slight taper on the width and a screw holding it

If they are road brakes, then yes AFAIK but maybe wait until someone else confirms

Guffy

Can anyone advise on the best way to clean a rusted chain and gears?

saccades

Guffy wrote: »

Can anyone advise on the best way to clean a rusted chain and gears?

Clean? Replace.



A weak phosphoric acid solution will remove the rust and passivate the surface against further oxidation. Loads of DIY places sell it near the hammerite, rust gone or the like.

magicbastarder

how badly rusted? and what will the bike be used for?

Guffy

magicbastarder wrote: »

how badly rusted? and what will the bike be used for?

Jist to and from work, bout an 8k cycle each way. I think it's at the borderline between save and replace.

The cassette and chainrings rusted too and is it just rust or have you oily crud build up on there too?

magicbastarder

not really a bike maintenance question - but nearly every time i connect my (cheapo) garmin to my phone via bluetooth, my phone informs me that there's a software update available for it, but it's fully up to date. garmin express lists a bunch of language updates, none of which i need. anyone else having this problem?

Macy0161

Well my connect app has been telling me "update available" for my 920xt several times a week recently.

LollipopJimmy

Same with my Garmin, I've no idea what garmin I have though, 500 I think. Every time I plug it in there's updates

Macy0161

Winter bike has a medium shimano cage which I run 11-32, the other a short cage with which I run 11-28. On the direct drive turbo, I currently use the winter bike, so it has an 11-32.

If I swap that for 11-28, should I be ok using either bike without any adjustments? i.e. can I just mount and ride the bike that's set up for 11-32 on the road without issue?

Paul_Mc1988

You can throw the 11-28 on the bike with the medium cage but would need to swap the chain also. The gearing shouldn't need any adjustments but id put the chain on the big cog at the back and unscrew the b-screw a bit so its spaced a bit better

cython

Paul_Mc1988 wrote: »

You can throw the 11-28 on the bike with the medium cage but would need to swap the chain also. The gearing shouldn't need any adjustments but id put the chain on the big cog at the back and unscrew the b-screw a bit so its spaced a bit better

Shouldn't need to change the chain unless there's a difference in wear between the cassettes - the smallest and largest sprockets in 11-28 are within the range of 11-32 (i.e. on 11-32 before you hit the lowest you may be in 11-28 depending on the cassette progression), so the latter chain can work with the same derailleur setup. It will just mean the rear mech never extends as much as it might on 11-32. As you say the b-screw may need some tuning, but that's minor enough.

Macy0161

Thanks, I'm not going to bother now I've thought on it. It was to allow for a crank power meter swapping between bikes*, but that's actually more hassle than putting the 11-28 on the turbo and just taking the good bike on and off for the summer, and then doing the same in the winter with the winter bike! I was just being a bit dumb when I had the thought.

*even though it is handy, on reflection I think a seasonal swap is better all around than trying to do it weekly.

Paul_Mc1988

cython wrote:

Shouldn't need to change the chain unless there's a difference in wear between the cassettes - the smallest and largest sprockets in 11-28 are within the range of 11-32 (i.e. on 11-32 before you hit the lowest you may be in 11-28 depending on the cassette progression), so the latter chain can work with the same derailleur setup. It will just mean the rear mech never extends as much as it might on 11-32. As you say the b-screw may need some tuning, but that's minor enough.

You learn somthing new everyday . Them few extra links would save a few gram though