| Which bike is faster, a full suspension bike (bouncer) or a hard tail?
Since I now have two mountain bikes, a Giant NRS full suspension bike and a
Giant Terrago hard tail, I decided to see which bike was faster over a
typical route that I ride. I used GPS based telemetry together with
Memory Map route planning software to analyse the bikes' performance over a
56 km mixed road and cross country route. From this I could see where
each bike was faster. |
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| bikes |
| route |
| telemetry |
| other |
| results |
| conclusions |
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Bikes
|
| |
Bouncer |
Hardtail |
| Bike |
2005 Giant NRS |
2007 Giant Terrago |
| |
 |
 |
| Front fork |
Rockshox Reba race, 115mm travel, air sprung, remote
lock out with adjustable blow off. Adjustable compression and rebound
damping, adjustable +ve and -ve air pressures. |
Suntour XCR, 100 mm travel, fork mounted lock out, no
blow off |
| Rear shock |
Cane Creek Cloud Nine, air shock with adjustable
compression and rebound damping. (Note that the shock is supposed
to lock out, but in practice the lockout is totally ineffective.) 3.75"
rear wheel travel. |
none |
| Brakes |
Giant MPH3 hydraulic discs |
Giant MPH3 hydraulic discs |
| Cranks |
Shimano XT |
Truvativ Isoflow |
| Rear mech |
Shimano XT rapidrise |
Shimano XT rapidrise |
| Shifters |
Shimano LX |
Shimano LX |
| Pedals |
Crank Bros, Egg Beater Ti II |
Shimano, M520 SPD |
| Wheels and tyres |
Non branded wheels with Kenda 26x2.1 tyres and Bontrager
self sealing tubes. 35 psi rear, 30 psi front |
Non branded wheels with Kenda 26x2.1 tyres and Bontrager
self sealing tubes. 35 psi rear, 30 psi front. |
| Accessories |
Wedge with tool kit and two spare tubes (800g) |
Wedge with tool kit and two spare tubes (800g) |
| All up weight |
15.5 kg |
15.5 kg |
| Rider weight |
70.5 kg |
70.5 kg |
| Cost |
~£1300 |
£480 |
|
| |
| The hardtail was a pretty much stock 2007 Giant Terrago with SPD pedals
and a XT Rapidrise rear mech (with 2 bikes you need both rear mechs
operating the same way round else it will do your head in). The
bouncer was a 2005 Giant NRS that had been gradually upgraded when bits wore
out. The cost of this bike allows for the base bike plus all of the
upgrades that have been added. It was a total coincidence that both
bikes weighed the same. Not a coincidence was the wheels and tyre
choice. Tyres can make a huge difference to performance so I ran with
the same tyres. I have 1.5 kg lighter wheels (Bontrager race disc) for
the NRS but these were fitted with unsuitable mud plugging tyres and I
couldn't be bothered to change them over, hence I just ran the stock wheels
and tyres off the Terrago on both bikes. The weight and cost figures
for the NRS take account of the actual wheels and tyres used. Both
bikes were in excellent mechanical condition. |
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Route
|
| The route was typical of what I ride, i.e. mixed road and cross country
of about 3 hours duration. Cross country is maximised with roads only
used to link up the good bits. It started and finished at my home in
Newbury, Berkshire. Obviously I could have put the bike in the van and
driven a short distance to cut down on the road mileage but that's not
how I normally ride and isn't exactly environmentally friendly. The
route was over down lands on the Hampshire - Berkshire border and consisted
of tracks and bridleways. There had been a 6 week dry spell so the
surface was hard, and rutted in places. |
| The route was 55 km long and had 735m of ascent and descent. It
was 54% road, 46% off road. The figures below show the map route, a 3D
view of part of the route and a Goggle Earth view. |
   |
| The following image shows the elevation profile of the route broken down
into cross country (green) and road (red) sections. Distance is in km.
 |
| I've done this route many times so navigation was not an issue. |
| |
Telemetry
|
| A Garmin Etrex (the most basic model) GPS unit was used to record speed
and location data. This was down loaded into Memory Map software for
analysis. |
| Timing was by stop watch which was stopped and restarted when I had to
stop and fix punctures, thus the route times are riding times |
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Other
|
| I used a Polar heart rate monitor for all runs to keep the effort
constant. I tried to cycle at a constant heart rate of between 150 -
160 bbm. I can keep this rate up for 3 hours no problem and its fast
enough that you have to put effort in, if I was just bimbling along my heart
rate would be slower. It was only possible to maintain the heart rate
limits on the road and on the uphill cross country sections, on the down
hill and flat(ish) cross country sections speed was limited by self
preservation concerns, i.e. I rode the bikes to the limit of my ability to
keep them under control. |
| For each ride I wore pretty much identical kit and carried a Camelback
with 2 litres of squash. In addition to the odd enforced stop to fix
punctures, I stopped once on each ride for about 2 minutes for a comfort
break and snack (1x KitKat). The stopwatch was stopped for these
breaks. |
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Results
|
| Run |
1 |
2 |
3 |
| date |
28 April 2007 |
5 May 2007 |
6 May 2007 |
| bike |
hardtail |
bouncer |
hardtail |
| weather |
sunny, no wind, ~20ºC |
cloudy, 9ºC, 72% relative
humidity, wind N, 8 mph |
cloudy, 14ºC, 76% relative
humidity, wind SW, 14 mph |
| GPS telemetry |
no |
yes |
yes |
|
time (hrs:min) |
3:09 |
2:56 |
2:59 |
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| So, the bouncer was between 3 and 13 minutes faster than the hardtail
over a 3 hour route. The following analysis only looks at the fastest
hardtail ride as this was the only one with telemetry. This is what
the speed profiles looked like. |
 |
| There are two flat spots on the GPS tracks for the hardtail. Both
occurred on steep off road sections where the vibration levels caused the
GPS to switch itself off. (The batteries were good, the unit switched back
on afterwards and continued running just fine. Doing a few jumps
afterwards showed that the shock would cause the GPS to switch off). |
| A bit more useful is a breakdown of where each bike was fastest.
Blue shows where the bouncer was fastest and red shows where the hardtail
was fastest. Road
Each block shows each of the road sections on the corresponding elevation
profile
One very good reason why the bouncer was faster on the initial road
section and slower on the same roads coming back was the wind direction,
there was a noticable wind slowing me on the hardtail going out and helping
coming back. Other than that the main section where the hardtail was
faster was the long, slightly uphill drag at about the 35 km mark. At
this point for both bikes it was a case of dig in, graft and use the heart
rate monitor to set the pace. Curiously, where I would have expected
the better pedalling efficiency of the hardtail to pay off was the big flog
uphill from 10 -12km, however, the telemetry showed both bikes to have the
same pace.
Cross country
Again, each block corresponds to the cross country sections of the
elevation profile.
Here the analysis is pretty clear, the bouncer is much faster. With
one exception, the uphill drag coming up to the 40 km mark where the
hardtail was faster over the middle section (but not the bottom or top
sections???), the bouncer wins hands down. Unfortunately, there are
two missing sections (flat lines) on the hardtail telemetry where the GPS
switched off due to excessive vibration. The 2nd time the GPS switch
ed itself off at the 41-42 km mark, I was flat out pedalling on the bouncer
whereas on the hardtail I was coasting with all my weight on the pedals
rather than the seat and occasionally dabbing the brakes. The flat
lines don't show the true average speed of the hardtail where telemetry was
lost as they show a "as the crow flies" average speed rather than an "along
the track" average speed. This certainly shows that I was really
pushing the hardtail at these points. |
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Conclusions
|
| So, the result shows that the bouncer is ever so slightly faster than
the hardtail, however, it was a £1300 suspension bike versus a £500 hardtail
and that works out at £800 per minute advantage per hour's riding. You
could of course spend more money on the hardtail and get it a lot lighter
and thus faster on the uphills. It should also be remembered that the
Giant NRS climbs superbly well for a bouncer. The rear shock is set up
with zero sag when you're sitting on the bike, it doesn't bob at all unless
you stand up out of the saddle. This may well have helped the bouncer
to keep up with the hardtail on the roads but the results clearly show that
once you get off road the bouncer is a lot faster. |
| The tale of the stopwatch isn't the only consideration. After the
hardtail rides I was seriously knackered with legs feeling like blocks of
lead for the rest of the day. Conversely, after the bouncer run I felt
fresh as a daisy. Although the times were close, riding the hardtail
took considerably more effort despite the heart rate being kept constant.
What happens is that when you see a big hit coming along you take weight on
your legs rather than the saddle and use your quadriceps as shock absorbers.
Of course, whilst you're doing this you're not pedalling and after a while
this gets tiring. On a bouncer you just sit there still pedalling with
the suspension doing all the work. |
| Route choice obviously has a huge influence on the choice of ideal bike.
If you spend all your time on tarmac then a road bike is ALWAYS going to be
quicker, period. Similarly, if you only ever take the gondola up and
ride the Fort Bill downhill course the a big hit bouncer is obviously going
to be quicker. In between are infinite shades of grey.
What's faster for me might not be faster for you, it all depends on your
route and the conditions. Here, the route was dry down lands where the
limit was either; traction on a loose/rough surface, trying to keep the bike
in a straight line through ruts, or self preservation when hitting water
run-off channels. The bouncer won out as it maintained far
better grip and in the ruts it held its line much better. On big hits
I had the confidence to take them at speed knowing full well the suspension
would cope. If the ground was soft and muddy - who knows? |
| From my perspective, the main reason for going for a bouncer rather than
a hardtail is FUN. There's no two ways about it, on the interesting
stuff not only is a bouncer faster and less tiring to ride, its also a lot
more enjoyable to ride. And surely that's what its all about? |
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