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Data screen (0.9.6)


Trip details screen (0.9.6)


Trainer/laps screen (0.9.6)


Log­ging details screen (0.9.6)

Log manager

Log Man­age­ment (0.9.6)


Speedometer screen (0.9.6)


VeloAce is the Open Source bike com­puter with log­ging and training func­tion­ality for Palm OS®. VeloAce is licensed under the terms of GNU Gen­eral Public License (GPL) ver­sion 2. Copy­right © 2005, 2006, 2007, 2008, 2009 Mark Häm­mer­ling.


VeloAce pro­vides a clear user inter­face showing the most impor­tant data on five dif­ferent screens:

  • Data screen: cur­rent, average and max­imum velocity, accel­er­a­tion, trip time, total and trip dis­tance,
  • Trip screen: total and remaining trip dis­tance and time,
  • Trainer screen: Top 10 or Last 10 laps, auto­matic and manual lap trigger,
  • Log screen: details about the run­ning log, but­tons for inserting markers, and a dis­tance vs. velocity graph,
  • Speedometer screen: a clas­sical analog rep­re­sen­ta­tion of the cur­rent velocity, including trip and total odometer.

VeloAce can record logs of your bike trips and allows you to beam these logs to friends or to your note­book or PC for fur­ther anal­ysis.

Using Palm PDA hard­ware has sev­eral great advan­tages:

  • VeloAce runs on hard­ware that is nowa­days con­sid­ered obso­lete and which is there­fore very inex­pen­sive to get
  • it uses the bril­lant dot matrix touch­screen with even back­light capa­bilty
  • it can use the already installed RS232 or IrDA hard­ware to inter­face to your wheel sensor

The Palm PDA can simply be con­nected to your wheel sensor over these inter­face cir­cuits:

  • VAIF-1 for very simple con­nec­tion over RS232 (spare Hot­Sync cable rec­om­mended)
  • VAIF-2 for simple con­nec­tion over IrDA (also allowing even more modern Palm PDAs to use VeloAce)


  • detailed trip data log­ging (Perl scripts for con­ver­sion to CSV are included)
  • scrolling graph with dis­tance vs. velocity (recent 158 wheel rev­o­lu­tions)
  • detailed data dis­play: cur­rent, average and max­imum velocity (km/h, mph), accel­er­a­tion (g), trip time (h:m:s), total and trip dis­tance (km, miles)
  • training capa­bil­i­ties with Top 10 or Last 10 laps and manual and/or auto­matic lap trig­gers
  • detailed trip data: total trip dis­tance (given by user), com­pleted trip dis­tance, remaining trip dis­tance, total trip time (esti­mated), com­pleted trip time, remaining trip time (esti­mated), trip pro­gress bar and per­centage
  • clas­sical speedometer view with analog dis­play, total and trip odome­ters

New fea­tures of VeloAce 2009

  • High-pre­ci­sion timing finally allows us to have a much more pre­cise cal­cu­la­tion of the cur­rent velocity and a much quicker response to incoming sig­nals. This fea­ture requires CPU sup­port and is there­fore only avail­able on Motorola 68k CPU based devices (which applies to any device that runs the sup­ported Palm OS ver­sions).
  • The new UI font gives you a new sportive user expe­ri­ence. Please note that the screen­shots at the right were gen­er­ated with an ear­lier ver­sion. To check out the new look, just down­load VeloAce and find out by your­self. ;-)
  • Ver­sion 2009.6 also sup­ports log recording with the advanced Log1 stream format, allowing users to record high-pre­ci­sion timing in logs. Stream format spec­i­fi­ca­tion included with VeloAce.

Ear­lier fea­tures (up to 0.9.6)

  • Miles and mph sup­port! VeloAce can now also dis­play dis­tances in miles and speeds in mph, in addi­tion to kilo­me­ters and km/h. You can choose between both base units in the pref­er­ences dialog.
  • Trainer screen! This new screen offers you to com­fort­ably mea­sure and setup the total length of one lap. During your training you are kept up to date about your per­for­mance with the Top 10 lap list, which shows you the lap number, the lap time and the lap average speed for each one of your 10 best laps. The least recently added lap is high­lighted. You can also choose to dis­play the Last 10 laps instead. A new lap can be trig­gered by pressing the "page down" hard­ware button ("Manual" trigger) and/or auto­mat­i­cally when the lap length has been reached ("Auto" trigger).
  • IrDA sup­port! Using a very trivial cir­cuit ("VAIF-2"), it is now pos­sible to con­nect your wheel sensor not only in a wire­less way, but also to Palm devices that have no RS232.
  • Log man­ager! Now you can manage your recorded log databases from within VeloAce. Using the log man­ager you are able to beam logs to friends or to your PC for anal­ysis. Also, you can get an info about a log, rename or delete it, and even append a log recording to an existing log database.

What you need

Note: Usage is not nec­es­sarily restricted to these plat­forms, but they have been suc­cess­fully tested and are there­fore rec­om­mended.

PDA Hard­ware

PDA hard­ware that is known to work:

  • Palm IIIx
  • Palm IIIxe
  • Palm Vx
  • Palm m100
  • Sony Clié PEG-S360
  • Hand­spring Treo 300 (slow screen updates)

Thanks to Michael Elliott for reporting status of the m100, Clié and Treo devices.

All listed devices have flash ROM (using spe­cial tools, VeloAce can even be put in there), the III models use stan­dard AAA bat­teries which you can quickly change on a trip, and since the older Palm models are today con­sid­ered obso­lete hard­ware, they are really inex­pen­sive to obtain (around 20€ at eB*y).

Palm OS

Palm OS ver­sions known to work:

  • Palm OS 3.5 up to 4.x

Note on Palm OS 3.3: I am trying to get it also working on OS 3.3, but it behaves badly in some cases - and it's not always easy to imple­ment a workaround for this old OS. So if you have a Palm with flash ROM, you should really upgrade to at least OS 3.5.

Note on Palm OS 5: If there are any pro­gram­mers with Palm OS 5 expe­ri­ence, please con­tact me. I would like to find out why Palm OS 5 freezes when a wheel rev­o­lu­tion is detected (I sup­pose the inter­rupt han­dler does not work as expected). I have no OS 5 PDA around, so I might need some testers once I've tried to fix it. Thank you Tomas and Ralf for reporting the OS 5 related prob­lems.

Wheel sensor inter­faces

  • VAIF-1 for RS232, or
  • VAIF-2 for IrDA con­nec­tion

The VAIF-1 has been the first offi­cial VeloAce RS232 inter­face. It's a simple con­nec­tion shorting RTS and RXD. No elec­tronic parts required.

The VAIF-2 is the first offi­cial VeloAce IrDA inter­face. Using just a dual non-retrig­ger­able monoflop, an infrared LED, and a few pas­sive parts, this trivial cir­cuit gen­er­ates an infrared light pulse which enables VeloAce to detect a wheel turn.

For details about the wheel sensor inter­faces, see the VAIF build instruc­tions PDF doc­u­ment.


Get VeloAce from Source­Forge or just choose the latest ver­sion from the Engbedded Down­load Server.

Testing without a cable

Even without the inter­face cable you can test VeloAce with a stan­dard infrared remote con­trol.

Just choose the VAIF-2 (IrDA) inter­face in the pref­er­ences. Then point your remote con­trol at the Palm and sim­u­late wheel rev­o­lu­tions by pressing any button on the remote con­trol. Depending on the IR pro­tocol used by your remote VeloAce will more or less prop­erly detect single wheel rev­o­lu­tions (try to press very shortly and/or try dif­ferent remote con­trols).

Alter­na­tively, you can use a serial ter­minal pro­gram on your PC, with the Palm con­nected via cable or cradle. Just open the RS232 port the Palm is con­nected to and send any char­ac­ters at any baud rate to sim­u­late wheel turns.

This way you can get a feeling how VeloAce works without having to get or build the cable first.

Hints for mounting the PDA to your bike

Mounting the PDA to your bike might be the trick­iest step. You've got to fix the Palm onto your handle bar.

If it helps you, you can rotate the Palm. Together with the "FlipHack" and "Flip Graf­fiti Hack" you can use your Palm in any direc­tion, maybe allowing you to access the appli­ca­tion but­tons in a more com­fort­able way.

I am plan­ning to mount a Palm Vx using its stylus grooves. I will report if it's robust enough.

My sup­port

If you've got any ques­tions or com­ments, an idea of a nice fea­ture, or code or art­work that you want to con­tribute, please don't hesi­tate to con­tact me.


I would like to thank these gen­erous people for having vol­un­tarily donated to the VeloAce pro­ject:

  • Fred, Day­tona Beach/USA
  • Tom Zalm­stra, Nether­lands
  • Russ Taber, Michigan/USA

Your sup­port

Devel­oping VeloAce has con­sumed a lot of my time. I've been really enjoying devel­oping it, and I appre­ciate every feed­back. If you got the feeling that you really, really like this pro­ject, and that you've maybe saved a lot of money because VeloAce offers you fea­tures that some of the most expen­sive bike com­puters can not provide, then please con­sider a dona­tion of what­ever amount you find appro­priate and give this pro­ject a suc­cessful future. I would really like to add your name to the list of donors (unless you don't want to be listed here). Many thanks in advance!

There is also a page that dis­cusses requested fea­tures for VeloAce.

Related pro­jects

  • Bikan: A graph­ical viewer for VeloAce and Bikini log files. Author: Joost Zalm­stra.