Cycling UK Forum

JEJV wrote:With your ?Oryx? brakes, you want the fat spacers on the rim side of the brakes, whereas with the CR520s in Colin's thread, the thin spacers should be on the rim side, for maximum leverage.

If you have the narrow spacers on the rim side of the brakes at the moment, swapping the spacers so the fat spacers are on the rim side might be enough to give a significant increase in the leverage.

That has the effect of moving the levers apart, and making the straddle wire more horizontal. To a first approximation the leverage is inversely proportional to the angle between one half of the straddle and the horizontal.

JEJV wrote:Why do you want to do this ? What are you trying to acheive ?
[...]
DO NOT attempt to fit drop bars to your existing stem. The radius will be wrong, and your bars may snap in the middle.

While you are riding.

If you replace your existing straddle wire with a CR520 style straddle wire - as used in the thread Colin linked to, you can follow the instructions in Colin's thread more easily.
Lowering the straddle increases the leverage. With your ?Oryx? brakes, you want the fat spacers on the rim side of the brakes, whereas with the CR520s in Colin's thread, the thin spacers should be on the rim side, for maximum leverage.

looking for CR520 spares in ebay cyclocross shops might be good.

The reason your kind of straddle wire exists is to prevent a front brake cable failure causing front wheel lockup, caused by the straddle wire falling onto the tyre - particularly a problem with knobbly tyres.
Old canti-braked MTBs often had a front reflector mount going under the straddle, to prevent this failure. Mudguards work too.

Bin the Tektro pads, and put Kool-stop or Swiss-stop in instead. V-brake pads are probably what you want. Kool-stop V-brake cartridge pads probably fit your exiisting pad holders, but I wouldn't guarantee that. We don't bother with cartridge pads any more, as the Kool-stop salmon or salmon/black pads wear so much slower than the various pads we used before.

At the back, you may want to set up the brakes for low leverage. Cantis seem the only brake system that allows different leverage front & back.

MikewsMITH2 wrote:
Wouldnt work for me though.

Oh Dear.

lackofgrip wrote:i currently have a straight bar on my hybrid and am wanting to change do drop handlebars.

The current bar is 25mm where as the drop handlebars are 25.8mm will the drops go in or will the 0.8mm cause a problem?

Why do you want to do this ? What are you trying to acheive ?
[These should have been the first questions asked]

Looks like you have a 1 1/8" threaded steerer. Flat bars are nominally 25.4 clamp (except some MTB, which have 31.8mm clamp [Edit:] & 22.2 BMX).

It can be worthwhile to convert a hybrid or MTB to drop bars, but there a lot of details to get right.

For example, how will you adjust the brakes ?

£400 doesn't seem unreasonable for a bike shop to do it right. If they know what they're doing.

Depending on what you are trying to do, there may be other, simpler, ways to acheive what you want.

DO NOT attempt to fit drop bars to your existing stem. The radius will be wrong, and your bars may snap in the middle.

petzl wrote:I need a frame/bike suitable for a 5ft 4in rider that will accept full mudguards with Nokian W240 700c x 40 studded tyres and has 135mm rear axle width. I have posted on the wanted board in addition to contacting many off the peg outlets, the problem is the clearance for 700c wheels and being a short rider.

A small 700C hybrid should work - A hybrid based on MTB components, not a flat-barred road bike. They seem to go up to at least 44mm treaded, with full mudguards. Once you have a model in mind, it shouldn't be too hard to find out the biggest tyres it will take. We have a few Giant CRS hybrids, which take can 47mm knobblies, with mudguards (53mm SKS).

[EDIT: - I'm suprised that you have difficulty finding such a thing - most bike shops sell them. They usually seem to come with 35mm tyres on 16-19mm rims. Maybe no-one will promise that tyres they've never seen before will fit. 19mm or bigger rims better for 40mm tyres.]

Then there's the usual problems of making a big-wheeled bike fit a short person, particularly if the rider wants their hands lower than their bum. But 5'4 isn't so short.

I guess the question is: do Nokian studs fit Marathon Winters. I don't know. I had an idea that they did, but I can't remember where I got that idea from. If I can get hold of some W240's I'll let you know.

Why would the studs need "preconditioning", and how would that help ?

- Bearing in mind Peter White's comments here: http://www.peterwhitecycles.com/studdedtires.asp Search for: "About the studs"


FWIW:
http://www.bike-components.de/products/ ... kung-.html
http://www.bike-components.de/products/ ... ikes-.html

I think you want a 9-speed Shimano MTB mech for a bigger 10-speed cassette with 105 brifters.

I think SRAM rear / SRAM brifters have a different cable pull. But I've never played with either.

Allegedly, Campy 10sp brifters work with an SRAM road rear mech:
http://velonews.competitor.com/2008/03/ ... -not_73404

Malaconotus wrote: I have measured my rear chainline using Sheldon Brown's method here.

Sheldon Brown and Shimano differ regarding chainline measurement.
This used to be on the shimano website: http://www.xza5.net/pipe214/CTC_10032/h ... inline.pdf
So, for a Shimano front mech, it's probably good for the chainset to be close to Shimano's idea of the right chainline - +/- a BB size.

Hang on - that's a deore M511 - it's designed for 44-48 rings, and at least 12 teeth difference between middle to big. Might be OK, though.

(it was 24/34/44 before or something like)

24/34/42 ; 22/32/42 ; and 22/32/44 are the likeliest possibilities.

I'd guess 24/34/42. How may gears are there at the back ?

Most MTB front (triple) mechs handle 48 teeth.

Shimano "Tourney" FD-C051 front mech or "Alivio" FD-M410 or FD-M412 are supposed to work on 28/38/48. These are (also) top or bottom pull, with clamp fittings for 34.9, 31.8, 28.6.


But the problem could be that the new chainset wants a different length bottom bracket to the old one. Front changing can get messed up if the chainset is too far out, or too far in. The problem might not be with the (old) front mech at all.

A 28-38-48 chainset might want 113mm or 122.5mm. Or something else.

Can you tell what the exact models of new and old chainset are ?

[EDITED TO FIX URL]

Sheldon is not infalible.

Shimano certainly have a different idea:

http://www.xza5.net/pipe214/CTC_10032/h ... inline.pdf

Note:

"Please note that on a triple front chain wheel, this is not the exact the same [sic] as the position of the middle chainring!"

Craggers wrote:

JEJV wrote:3mm out might suggest that you have a 118mm BB, or the measurement is wrong, or the frame is strangely skewed.

A 118mm spindle would only increase the chainline by 1.5mm over a 113mm spindle (1.5mm longer at each end)

2.5mm at each end.
You said 53mm; 113mm + 2*3mm = 119mm, so I guessed 118mm.

Oh, we (deliberately) use 107mm BB with M442 44-32-22 chainsets & FD-M590 or FD-M510 and that seems to work fine.

CREPELLO wrote:

JEJV wrote:

Craggers wrote:I think a BB with a shorter spindle is the order of the day then. My chainline at the moment is about 53mm.

How are you measuring that ? Shimano's idea of "chainline" is the centre of the small & large rings, not the location of the middle ring.

What is the difference then? I can't see that there would be any.

I think there are two things:
- It can be hard to measure to the middle of the middle ring
- The middle ring may not be in the middle.

IIRC, I got a couple of mm difference. It could just be me.

Shimano used to have a webpage which explained what they meant by "chainline", but I think it's gone now. I have a pdf of it - might try to post that later.

I had a similar problem - with the same chainset that we're talking about, as it happens - a few years ago. I mis-read the data sheet, & got a 115mm BB instead of a 110mm BB (I wanted a shorter than nominal BB to make up for 2.0mm of chainguard carrier). After some faffing about, front shifting was still ropey, so I started trying to figure out what was happening. First I tried measuring to the middle ring. The numbers I got didn't make sense, so I googled "chainline measurement" or something, & found the Shimano webpage. The shimano way, I think the measurement I got was 0.2mm off what would be expected for the BB I'd fitted, the chainset, and the 2.0mm chainguard carrier.

Craggers wrote:I think a BB with a shorter spindle is the order of the day then. My chainline at the moment is about 53mm.

How are you measuring that ? Shimano's idea of "chainline" is the centre of the small & large rings, not the location of the middle ring.

Craggers wrote:Shimano apparently think that a 113mm UN-26 BB with a M410 chainset will give a chainline of 50mm (which the mech works with), but there's no way I'm getting the chainset any further onto that spindle.

Yes, 113mm should give 50mm chainline (& it does for me, with the same chainset, to a couple of 10ths of a mm).

3mm out might suggest that you have a 118mm BB, or the measurement is wrong, or the frame is strangely skewed.

BTW, FD-M530 is spec'ed for a minimum 12-tooth big-middle difference, so it's probably not ideal on 42-32-22. Alivio FD-M412 might be better.