Mini V help

[lorenbike]

I ran the same trp mini vs as you also with a23 rims but 4600 tiagra levers for awhile... Basically I could bottom out the levers even with the pads really close to the rims no matter how much I adjusted them and trying thinline pads. Then I switched to Paul mini motos which had better pad clearance and power than the TRPs. Well worth the money if you can float the Paul's.

[coffeecherrypie]

Originally Posted by lorenbike

I ran the same trp mini vs as you also with a23 rims but 4600 tiagra levers for awhile... Basically I could bottom out the levers even with the pads really close to the rims no matter how much I adjusted them and trying thinline pads. Then I switched to Paul mini motos which had better pad clearance and power than the TRPs. Well worth the money if you can float the Paul's.

Uh oh...an excuse to by an expensive fancy bike part...

Thanks for the tip! Useful info.

[MikeD]

You could run canti brakes.

You could dump the Sora brifters and use Tektro, Cane Creek, or DiaCompe V brake levers and barcon shifters.

[Mark McM]

Originally Posted by MikeD

You could run canti brakes.

... which is the type of brakes an AlphaQ CX fork was likely originally made for. There doesn't appear to be a way to install a crown mounted cable hanger, so a stem or steerer mounted cable hanger would need to be used.

[C40_guy]

Originally Posted by Mark McM

... which is the type of brakes an AlphaQ CX fork was likely originally made for.

That *shouldn't* be relevant.

I've run both on multiple Alpha Q CX forks and I've gotten very good performance with the 8.4s and Record levers.

Also running standard TRP shoes, not thinline.

[C40_guy]

Originally Posted by lorenbike

Then I switched to Paul mini motos which had better pad clearance and power than the TRPs. Well worth the money if you can float the Paul's.

I've run both, found the Mini Motos more fiddly. I'm back on the TRPs.

[GregL]

I have a similar setup on a LeMond Poprad that I use as an "all-road" bike. The CX8.4 brakes work fine with Shimano ST-5800 levers. As others have noted, older cross bikes with comparatively narrow brake post widths place the brake arms in non-vertical positions when wider rims are used. I partially compensated for this with spacer placement. On the whole, my braking power/modulation are good.

Greg

[Mark McM]

Originally Posted by GregL

As others have noted, older cross bikes with comparatively narrow brake post widths place the brake arms in non-vertical positions when wider rims are used. I partially compensated for this with spacer placement.

This should be a good thing. The issue with using linear pull brakes with road levers is that they have a higher mechanical advantage (leverage ratio) than the road calipers that road levers were designed for. Anything that reduces effective arm length of linear pull brake should improve pad clearance.

Single pivot road calipers have a leverage ratio of about 1:1. Dual pivot brakes with a single offset pivot have a leverage ratio of about 1.5:1. Dual pivot brakes with dual offset pivots have a leverage ratio of about 2:1. Mini-V linear pull brakes typically have leverage ratios of 3:1, depending on arm length and mounting stud location. So the cable travel of road levers designed for side pull calipers will always be a poor match to mini-Vs. But the closest match will be road levers designed for dual pivot brakes with dual offset pivots (such as Shimano 11spd levers).

A Travel Agent will increase cable travel by a ratio of about 2:1, making the overall leverage of a Min-V + Travel Agent about 1.5:1, or about the same as a dual pivot brake with a single offset pivot.

Coming from a different angle, the leverage ratio of a typical low-profile cantilever brake is about 1:1. This is a better match to most road levers (and partly why cantilever brakes were used with road levers on 'cross bikes for so long). A cantilever brake with longer arms will increase its leverage ratio. The leverage ratio can also be increased by lower the straddle height, but this carries the disadvantage of a falling leverage rate (leverage ratio decreases as the brake is actuated).

The leverage ratio of a Mini-V is only affected by the height of the mounting studs, the height of the brake track, and the vertical height of the cable attachments*. Moving spacers around on the pads will not change the heights of the mounting stud or brake track, and will have only a minor affect on the vertical height of the arms. Moving the pads spacers around will also have no affect on the arc of travel of the pads at the rim - this is only affected by the relative locations of the mounting studs and brake track**. However, a wider rim will decrease the downward arc of the pad (but will still have no effect on leverage ratio).

*This was one of the advantages of V-brakes over cantilevers: V-brakes have fewer variable, so it is easier to set up, and harder to set up wrong. But the caveat here is that levers have to be matched to the brake, because there is no way easy way to match their leverages.

**The exception here is for V-brakes with the pads actuated on parallograms - the parallograms keep the pad travel more horizontal, and reduce pad dive at the rim.

[Mark McM]

Another thing to mention: Although the leverage ratios of Mini-Vs and road levers aren't well matched, you can at least minimize lost cable travel. Standard brake housing compresses slightly, increasing the required lever travel. The use of compressionless cable housing can decrease lever travel to some extent.

[bart998]

Originally Posted by Mark McM

Another thing to mention: Although the leverage ratios of Mini-Vs and road levers aren't well matched, you can at least minimize lost cable travel. Standard brake housing compresses slightly, increasing the required lever travel. The use of compressionless cable housing can decrease lever travel to some extent.

THIS^^^ I've now run compressionless brake cable housing on several bikes with "soft" brakes.... Makes a definite difference... for cheap.

[benb]

I ran a lot of the CX9s (discontinued IIRC) on my All City Space Horse.

Right now it has a flat bar on it with $20 Shimano full size V-brakes and $20 Avid levers and the braking is phenomenally better than the Mini-Vs.

But god I hate the flat bar, that bike fit for me just handles much better with a drop bar. This thread is just reminding me if I switch it back to drop bars I get to deal with the brake situation again.

I would expect the CX8.4s to work better on my bike but they will reduce some of the fender clearance which stinks.

I always got good performance out of the CX9s but they would tend to just be very very needy with tuning of the brakes based on pad wear at least once a month. I rode the $20 full size Vs all last year and basically never touched them except tightening the barrel adjuster once or twice, zero need to fiddle with the balance between the two sides to deal with uneven wear.

[reuben]

Good compressionless cables such as Jagwire Pro are a big help. There's also some sort of preadjustment which I can't recall at the moment, which is a big help but possibly difficult, or even impossible in some situations. It's in the TRP 8.4 instructions. I'm sure that someone with a better memory than mine can clarify this.

[RWL2222]

Err...'lil bit of thread drift here, but if anyone has it, I am in need of a mounting bolt for these CX8.4 brakes. Having checked with TRP, seems they are not so easy to come by. [edited]

[C40_guy]

Originally Posted by RWL2222

Err...'lil bit of thread drift here, but if anyone has it, I am in need of a mounting bolt for these CX8.4 brakes. Having checked with TRP, seems they are no so easy to come back.

I might be able to help you out. Will you PM me with. a photo and description of what you're looking for? I've got a couple of flaky calipers and can probably spare a bolt...

[coffeecherrypie]

Update, I put thinlines on and was then able to put the pads higher in the slots, the braking is definitely somewhat better now, I can't bottom out the lever any more although it's close. May try compressionless housing in the future. Or a travel agent.