mountian bike to road bike for commuting

daddy0

kenan wrote:

After feedback from people who have changed their mountain bike for a road bike to commute as I'm planning to do this. Read lots of threads of bike vs bike etc but wanted feedback from people who had made the change.

Currently riding a HT I put together from spare parts in the garage and now those bits are falling apart thought I’d get a road bike to replace it.

I went from a MTB style hybrid with 29" wheels to a road bike this year. The hybrid started falling apart so I upgraded bits on it and put rigid forks on it. I realised that by trying to make it more efficient I was trying to make it more like a road bike... So I got a £1000 carbon jobbie through work and relegated the old hybrid to "wet bike". Have loved it so far, although I have fallen over once whilst making a slow turn - doah!

If you're riding 100% on the road then get a 100% road bike. If you're planning on riding through puddles then maybe get a CX bike with discs, otherwise I wouldn't bother, I just avoid the puddles. My 105 brakes stop me fine, its the tyres that are the issue in the wet. Remember that skinny tyres have less grip!!!

My commute is about 6.5 miles, at the end of it is a 1.5 mile hill climb, which gets quite steep. My main concern was that the road bike gearing would make this too hard. I went from the lowest gear of 28x32 on the hybrid to 34x25 on the road bike. But I put in about the same amount of effort, maybe a tad more, and I go up the hill faster. Turns out I don't even need the lowest gears on the road bike anyway. Going down it at the end of the day is where the road bike really shines though. I have managed to get 55mph and could go faster if I was braver - the most I got on the hybrid was 45mph and that took my full effort :-)

jeepie

What's wrong with SRAM Apex - MRS? "many ways". I've got Ultegra and prefer Apex - just interested.

meanredspider

Jeepie wrote:

What's wrong with SRAM Apex - MRS? "many ways". I've got Ultegra and prefer Apex - just interested.

Have a read of the Boardman CX thread and you'll see quite a few complaints about the Apex front shifting (even in the most recent posts). Also I think you'll read that, like me, people found the brakes far more positive with 105 fitted as the levers don't flex as much. Additionally, I think the large "paddles" on the gear shifters tended to catch and interfere with the bars quite readily unless kept well adjusted. Generally I found Apex far more "agricultural" than 105. Just opinions of course but I think there's a few of us with the same view.

jeepie

OK - cheers. Will have a read... Thanks MRS. I had a lot of problems with my first 105 LH shifter as they sold double and triple as the same STI... I've upgraded to Ultegra now but perhaps this put me off a bit....

JamesB5446

meanredspider wrote:

Hydraulics have the added advantage of the fluid being incompressible and the callipers "self-adjusting"

They have the disadvantage that the fluid can boil off.
Not so much of a problem on a CX as your speed is lower, so you have less energy to transfer into the brakes.

Kieran_Burns

meanredspider wrote:

Jeepie wrote:

What's wrong with SRAM Apex - MRS? "many ways". I've got Ultegra and prefer Apex - just interested.

Have a read of the Boardman CX thread and you'll see quite a few complaints about the Apex front shifting (even in the most recent posts). Also I think you'll read that, like me, people found the brakes far more positive with 105 fitted as the levers don't flex as much. Additionally, I think the large "paddles" on the gear shifters tended to catch and interfere with the bars quite readily unless kept well adjusted. Generally I found Apex far more "agricultural" than 105. Just opinions of course but I think there's a few of us with the same view.

My Apex front shifter is a pain in the bum as well. Very inconsistent and no proper feedback when changing up. It's pretty much the only mark against the Felt.

meanredspider

JamesB5446 wrote:

meanredspider wrote:

Hydraulics have the added advantage of the fluid being incompressible and the callipers "self-adjusting"

They have the disadvantage that the fluid can boil off.
Not so much of a problem on a CX as your speed is lower, so you have less energy to transfer into the brakes.

Yup - depending upon what fluid you use and how well you maintain it. Frankly, though, if you're in that realm (as I believe was reported in someone's blog) you were dragging your brakes down some long, steep incline and you deserve to end up in the hedge. A carbon wheel with rim brakes would probably fail in the same circumstances (carbon wheels are being banned from mountainous sportives in the US).

I think the advantages far outweigh the negatives.

Interested in this review http://www.bikeradar.com/road/gear/cate ... c-12-46747 that, even on £4000 bikes BB7 are the standard. It says a lot for the brake that it covers such a wide range and does a pretty good job else someone would have come along and developed something better (as they have with most other components)

supersonic

But it also says this:

Some might find the BB7 grabbier than a properly adjusted rim brake and, in fairness, there is some truth to that. However, it doesn't take long for your fingers to adjust, and we'd rather have the power and control on hand. Avid's long-running mechanical discs do require very careful setup for optimal performance, though – the pads don't self-adjust for wear, and pad clearance is disappointingly minimal.

So as before, if weighing them up, the OP would benefit from the full picture.

meanredspider

I linked to the whole article to let the OP read the whole thing but, in the interests of balance, the first part of the BB7 description says

Avid's BB7 single-piston mechanical disc brakes work well, too, despite the fact that they were originally designed before SRAM even had a road group on the market. While we would strongly advocate switching to compressionless housing on the rear brake – for better lever feel – overall power and modulation are excellent, especially in inclement conditions, where a rim brake is generally more hit-or-miss, or when pulling the levers from the hoods.

I've also said (above) that the advantage of hydraulic discs is that they do self-adjust. Neither mechanical disc nor rim brakes self-adjust. Setting up BB7s is important but it's also very easy if you follow the technique and no harder than setting up rim brakes. It says a lot for them though that they appear on £1000 bikes and £4000 bikes. You're unlikely to find many other key components making that jump - especially one that was never designed for that specific application.

JamesB5446

Worth looking at.
https://www.dropbox.com/s/nt7z58u1ntz8y ... addisc.jpg

meanredspider

JamesB5446 wrote:

Worth looking at.
https://www.dropbox.com/s/nt7z58u1ntz8y ... addisc.jpg

Yup - though I'm guessing there aren't that many 200lb riders that reach 50mph and brake to 15mph 7x in a 15 minute period. Whilst I'm sure these scenarios exist, it's not one that's going to be keeping me up at night. Since there are hardly any road hydraulic set ups just now, I'm glad they are doing the testing at the limits of the envelope.

cyclingprop

meanredspider wrote:

JamesB5446 wrote:

Worth looking at.
https://www.dropbox.com/s/nt7z58u1ntz8y ... addisc.jpg

Yup - though I'm guessing there aren't that many 200lb riders that reach 50mph and brake to 15mph 7x in a 15 minute period. Whilst I'm sure these scenarios exist, it's not one that's going to be keeping me up at night. Since there are hardly any road hydraulic set ups just now, I'm glad they are doing the testing at the limits of the envelope.

Why do they use a 200lb rider as an example, thats hardly big....

meanredspider

cyclingprop wrote:

Why do they use a 200lb rider as an example, thats hardly big....

It's 90kg - about 30-50% more than a pro rider

I'm 90kg - I'd consider myself a reasonably big guy on a bike. You then have to think about who is going to haul themselves to the top of a mountain high enough to reach 50mph (braking to 15mph) 7 times - that's not a small hill.

JamesB5446

It's rider plus bike. So I'm bigger than that. I've never scrubbed off 35mph quickly 7 times in a row though.

meanredspider

JamesB5446 wrote:

It's rider plus bike. So I'm bigger than that. I've never scrubbed off 35mph quickly 7 times in a row though.

You're correct - rider + bike. On the balance though, I think they're assuming that you're only using one brake as well - I think the scenario is pretty extreme.

JamesB5446

I dunno, the vast majority of the energy will be going through the front brake.

roger_merriman

JamesB5446 wrote:

Worth looking at.
https://www.dropbox.com/s/nt7z58u1ntz8y ... addisc.jpg

The impartiality of that article is rather in question since this is Magura who do have a lot to loose.

Some rather dubious comparisons in there as well.

meanredspider

Yup - I wasn't going to go down that route but, if you're developing hydraulic rim brakes, it's in your interests to question your key competition. What they don't examine is what rim brakes will do in the same circumstances - carbon rims and tyres have been known to fail in the same circumstances (as I say, carbon rims are banned on some events) - it's an choice I'd rather not make but I think I'd rather have my brakes go spongy than have my front wheel or tyre fail. And, to their point, high-end sports motorbikes don't switch to braking using rubber blocks on their rims....

JamesB5446

Yup, a rim is just a really big 'disk' so can dissipate that heat a lot better. Problem is a lot of that heat goes in to the tube/tyre.

You can't really compare with motorbikes as they use much bigger disks than bicycles, where weight is an obvious issue.

Rim brakes with a way of stopping the heat damaging the tube/tyre or disk brakes with a way of preventing fluid boil off would work.
One thing I'm interested in is when we'll see ABS on bikes, should be pretty easy with hydraulics and few sensors and servos. Who knows, that along with electronic shifting, could be seen on mainstream sub grand bikes in the next ten years.

meanredspider

As with car racing, you just need fluids with higher boiling points. F1 discs reach 1000C and yet use hydraulic brakes. My race car uses a race fluid with a very high BP fluid (312C) - I don't know what bike fluid boils at (can't find a reliable reference). It's the easiest way of solving the problem.

JamesB5446

Do those fluids have worse performance at lower temps though, in the same way that race car tyres do?

meanredspider

Nope - they're just expensive (relative to standard brake fluid)

JamesB5446

Might try to syphon some off a car next time I'm at Cadwell to stick in my mountain bike.

supersonic

Bike brake fluids are DOT 3, 4 or 5.1, or mineral oil.

meanredspider

supersonic wrote:

Bike brake fluids are DOT 3, 4 or 5.1, or mineral oil.

Ah OK - the stuff I use in the car (Motul RBF600) has a BP of 312C which is 42C higher than the minimum for DOT5.1 (the most demanding of those specs) though I think it's technically a DOT4 fluid (don't ask me why). I use it because it's actually reasonably priced (relative to other racing brake fluids) but of a high spec. With frequently bleeding of the brakes plus any maintenance & repair that might be needed, it's a great product and has never let me down on the track.

veronese68

The downside of high boiling point brake fluid is that it is very hygroscopic. So it needs to be replaced more often as the boiling point drops rapidly as it absorbs moisture. Not a big deal if you're prepared to replace the fluid every year or so. This should be done with regular brake fluid every 2-3 years, but people rarely bother.
That's in a car system that is vented. I don't know how much you could extend this by in a completely sealed bicycle system. Theoretically forever.

meanredspider

Veronese68 wrote:

The downside of high boiling point brake fluid is that it is very hygroscopic. So it needs to be replaced more often as the boiling point drops rapidly as it absorbs moisture. Not a big deal if you're prepared to replace the fluid every year or so. This should be done with regular brake fluid every 2-3 years, but people rarely bother.
That's in a car system that is vented. I don't know how much you could extend this by in a completely sealed bicycle system. Theoretically forever.

Absolutely. I doubt race brake fluid ever stays in the system long enough to be a problem in race cars. And, as you say, it shouldn't be an issue in bike systems.

supersonic

Unfortunately it can be an issue in some bike braking systems - I have seen lot of DOT fluids that are very milky after use, indicating moisture has got in. After all air gets in - which is why we bleed, and so does water unfortunately.

It does seem to take a while for this to happen, and it helps to degass the DOT fluids first. Mineral oil, as used by Shimano, has a lower boiling point, but is much less hygroscopic. The heat shedding capabilities of their latest icetech stuff is improved too (if you are the sort to drag brakes a lot)





Note this is rotor surface temp, not the oil.

JamesB5446

Hmm, hard to know if the disks are cooler because they're transferring more heat to the oil.